The Garden Shed
A Community Newsletter published by the Piedmont Master Gardeners
April 2019-Vol.5 No.4
For comments, questions or suggested topics for future Garden Shed articles contact us at: garden-shed@piedmontmastergardeners.org.
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Table of Contents
In the Ornamental Garden
Consider these blue-flowering, shrubby, deer-resistant plants.
Upcoming Events
Take a class, enjoy a lecture, tour a garden, shop at the PLANT SALE!
Tasks and Tips
The Ornamental Garden in April
April garden chores bring joy; Wineberry presents a challenge.
Feature
Blueberry Cultivation in the Home Garden
With good management, blueberries can reward gardeners with delicious, healthy fruit for twenty years.
April in the Vegetable Garden
Vegetable gardening really gets going in Central Virginia during April. The weather can still be pretty unpredictable though, so it pays to be “frost cautious.” Albemarle County and its surrounds are on the borders of the Piedmont and Mountain regions of Virginia. Extension Publication 426-331 puts Albemarle County in the Mountain region which has an average final frost date of May 10-15. On the other hand, USDA places Albemarle in Hardiness Zone 7a which specifies a final frost date of April 20-30. So planters beware, if you are motivated to plant warm weather crops early, be prepared to protect them if a surprise late freeze is our fate this year.
A separate-but-related guide to planting is soil temperature. Planting before soil reaches an appropriate temperature for your crops only delays germination or growth and really defeats the purpose of early planting. Investing in a soil thermometer is a wise move. On the other hand, warm soil is NOT an indicator of frost risk, so consider both variables in your planting decisions. A chart providing information on soil temperatures for optimum germination of vegetable seeds can be found in VCE Publication 426-316, titled “Seed for the Garden.”
Following is the April vegetable-planting schedule adapted from the VCE Publication 426-331. To identify transplants that can be planted outdoors this month, look for the vegetables marked with an asterisk.
| April 1-11 | April 12-18 | |
| Asparagus | Beets | |
| Beets | Broccoli* | |
| Broccoli* | Brussels Sprouts* | |
| Brussels Sprouts* | Cabbage* | |
| Cabbage* | Chinese cabbage* | |
| Chinese cabbage* | Carrots | |
| Carrots | Cauliflower* | |
| Cauliflower* | Swiss Chard | |
| Swiss Chard | Collards | |
| Collards | Leeks | |
| Leeks | Lettuce, Bibb | |
| Lettuce, Bibb | Lettuce, leaf | |
| Lettuce, leaf | Mustard | |
| Mustard | Potatoes | |
| Onions set) | Onions set) | |
| Potatoes | Potatoes | |
| Radishes | Radishes | |
| Spinach | Spinach | |
| April 19-25 | April 26- May2 | |
| Beans, Bush | Beans, Bush | |
| Beans, Pole | Beans, Pole | |
| Beans, Wax | Beans, Wax | |
| Beets | Broccoli* | |
| Broccoli* | Brussels Sprouts* | |
| Brussels Sprouts* | Cucumbers | |
| Cabbage* | Swiss Chard | |
| Swiss Chard | Cucumbers | |
| Cucumbers | Eggplant* | |
| Lettuce, Bibb | Muskmelons | |
| Lettuce, leaf | Onions set) | |
| Onions set) | Peppers* | |
| Pumpkins | Pumpkins | |
| Squash, Summer | Squash, Summer | |
| Squash, Winter | Squash, Winter | |
| Watermelon | Sweet Corn | |
| Sweet Potatoes | ||
| Tomatoes* | ||
| Watermelon | ||
| * Denotes Transplants | ||
| The suggested dates may vary for different areas. | ||
There’s still time. Tomato, eggplant, and peppers can still be started indoors from seeds.
April is the time to set out cool-weather crops such as broccoli, brussels sprouts, cabbage, cauliflower, lettuce and onions. But we have to wait until the danger of frost has passed to transplant tender plants such as tomatoes, peppers, and eggplant.
Photo: blog.gardenharvestsupply.com
If you’re interested in starting an asparagus patch, April is planting time. Asparagus is a perennial that requires a permanent location, full sun and well drained soil with a pH close to 7.0. Plants can last 15 years or more, so careful location selection is important. Asparagus can be started from seeds or crowns. Crowns are a good idea since it takes a few years for the plants to reach peak harvest potential. For an excellent guide to starting asparagus, read Cleve Campbell’s article “Spear into Spring with Asparagus” in the March 2015 issue of The Garden Shed, https://pmgarchives.com/article/spear-into-spring-with-asparagus and Va. Cooperative Extension Publication No. 426-401, which specifies recommended cultivars for Virginia, Extension Publication 426-401.
Having trouble with plant markers fading when labeling with a “permanent” marker? Paint markers available from supply stores or Sharpies marked “paint” from craft stores, hold up well throughout the growing season.
Go vertical to save space in your garden. You can construct temporary or permanent woven wire “fences,” which will provide vertical support for runner varieties of beans, as well as for cucumbers. Plants can be trained to climb the fences, saving not only space, but also making harvesting easier. For additional information on vertical gardening, see “Intensive Gardening Using Trellises, Stakes and Cages,” https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/HORT/HORT-189/HORT-189-pdf.pdf.
Saving Space: Snow peas growing up a temporary fence. Note the sequential planting of “pole” Lima beans at base of fence.
When planning your crop arrangement, consider intercropping. Intercropping is growing two or more plants together for a variety of beneficial effects including weed suppression, balancing fertility impacts, reducing pests, thwarting disease and adding diversity. Find guidance on effective intercropping here.
One of the most important steps in planting comes before seedlings get near the garden. This is the process of hardening off, or gradually acclimating seedlings to outdoor conditions. These young plants have spent their short lives in a warm, protected place and won’t fare well if they are exposed too quickly to the elements. Start the hardening off process about 2 weeks before you intend to plant them outside. A few days before beginning hardening plants off, reduce the amount of water you give them, and cease fertilizing until they are planted in the garden. Put transplants outdoors in an area where they’ll be protected from the direct sunlight and wind. Leave them out for a few hours and bring them back inside. Repeat each day, gradually increasing the amount of time they are outside and the degree of exposure to sun and wind. After a week or so, leave them out overnight. If frost threatens, bring the seedlings indoors. Additional information on hardening off can be found at VCE Publication 426-001 titled “Plant Propagation From Seed.”
When transplanting seedlings in peat pots, gently tear off the top inch of the pot; the upper edges of the pot should be covered with garden soil to avoid wicking water away from the soil surface. Wicking may reduce the amount of moisture available to plant roots.
The best time to transplant is on a cool cloudy day or late in the afternoon to avoid the hot sun. The plants then have time to acclimate to their new environment. If the following day is hot and sunny, a row cover may be used to reduce stress on the plant. A row cover may also be used to help protect young transplants from a late frost.
Don’t be in too big a hurry to add mulch to the vegetable garden. Delay organic mulching to allow the soil to warm deeply, but mulch before weeds become established.
Save The Date! Join us at the Piedmont Master Gardener Annual Spring Plant Sale on May 4, 10-2:00 pm at the Tent at Stonefield in Charlottesville.
Resources:
Adapted from “Monthly Horticulture Tip Sheets,” Albemarle County Extension Office website, Horticulture & Natural Resources, albemarle.ext.vt.edu/programs/horticulture-natural-resources
Blueberry Cultivation in the Home Garden
Blueberries are a popular fruit for a lot of good reasons. They have a unique flavor, small edible seeds, can be eaten fresh, and in jellies, jams, pastries, pies and juice. They are low-calorie with no sodium or cholesterol and are a source of fiber. The fiber source, pectin, has been shown to lower blood pressure. They contain ellagic acid which has been shown to inhibit chemically-induced cancer. And various sources indicate that blueberries help reduce the effects of urinary tract infections and glaucoma while improving memory. No wonder they are called a miracle food!
From a gardening standpoint, they are a woody perennial shrub that produces an annual crop of ¼” to ¾” berries. They are a member of the Ericaceae family, related to azaleas and rhododendrons. They are found naturally in well-drained, nutritionally poor, organic soils. Well- managed plants can produce for about 20 years. Major commercial production takes place where such soils are prevalent, including southern New Jersey, southwest Michigan and the Carolina coastal plains. They can be grown in other areas with appropriate site preparation, cultivar selection and ongoing site and cultural management.
Site Selection and Preparation
The best sites are in full sun (at least 6 hours per day), on gentle slopes where cool air and surface water both drain well. Flowers will tolerate mild frosts, but can be damaged by hard frosts and plants should not be located in low lying areas where cold air settles. Plant size varies somewhat with the cultivar, but 5-foot spacing between plants is typical. They can be arranged as a dense hedge, foundation planting or integrated with ornamentals. While many cultivars are self-pollinating, planting at least two cultivars together is recommended since cross pollination produces larger berries, higher yields and earlier ripening. Because most varieties flower at about the same time, careful selection can provide the benefits of cross pollination while extending the harvest season.
Ideal soils are silt loams to sandy texture with 2-3% organic matter. Plants are intolerant of waterlogged soils. Surface and internal drainage are critical to avoid root rot. Raised beds are often employed to improve drainage. Adding composted organic material is recommended to aid both water infiltration and drainage.
Blueberry bushes require a soil pH of 4.5 to 5.2, quite acidic. Addition of agricultural sulphur is the recommended amendment for soils above this pH range. Best to have soil tested and begin amendments in the year prior to planting. Regular testing and continued amending is recommended where soils aren’t naturally in the right pH range as they tend to revert to their natural pH level.
Cultivar Selection
Photo: University of Delaware Carvel REC
There are several species of blueberry — the lowbush (Vaccinium angustifolium); the highbush (Vaccinium corymbosum; and the rabbiteye (Vaccinium ashei). There are three types recommended for Central Virginia:
- Northern highbush
- Southern highbush
- Rabbiteye
Best choices are influenced by “chilling hours” — the number of hours per year that are in the 35-45 ºF. range needed to satisfy plant dormancy requirements. Northern highbush is best in northern Virginia and the mountain region. Southern highbush and rabbiteye are most appropriate in the central Piedmont, east and south, hardiness zone 7a and higher.
Southern highbush and rabbiteye varieties are hybrids of the northern highbush and are more soil-adaptable and heat-tolerant.
A quick listing of some approved cultivars includes:
- Rabbiteye
- Early blooming: Alapaha, Climax, Premier, Titan, Vernon
- Mid: Brightwell, Powderblue, Tifblue
- Late: Centurion, Ochlakonee
- Southern highbush:
- Early: Suziblue, Palmetto, O’Neal
- Mid: Camellia, Jubilee, Magnolia
- Northern highbush
- Early: Duke, Earliblue, Patriot, Spartan
- Mid: Bluecrop, Blueray, Legacy
- Late: Elliott, Jersey
Note that the early bloomers are most susceptible to frost damage.
Whichever variety is selected, look for vigorous two year old plants about 15 inches high. Keep bare roots or root balls moist if not planted immediately.
Planting
Plant bare root plants in February-March as soon as soil is workable. Container plants are best planted in the September to November period to allow root development over winter. Holes should be twice the size of the root ball. Mix organic matter with prepared soil. Water well before and after planting.
A 3” thick mulch, preferably of pine straw, pine bark or sawdust is recommended to assist in pH management, to maintain moisture, and to control weeds. Sulfur can be added to the mulch surface for further acidification as needed. If voles are a problem, a thinner mulch layer is warranted. Plants require 1-2” of water per week. Blueberry plants are relatively shallow rooted, spreading to only 1 ½-2 feet below the surface.
Best not to allow new plantings to bear fruit until they reach about 30” in height. Remove buds when planting to allow stronger shoot growth and to increase future yields.
Pruning
Pruning blueberry bushes is very important to maintain productivity. During the first three years, remove low spreading canes, dead and broken branches. After maturity, regular pruning between leaf fall and spring growth is recommended. Cut out old, dead wood. Keep the 3 best one-year-old canes. Prune out about 1 of 6 of the oldest canes, as close to ground level as practical. The goal is to end up with 10-15 total canes, 2 to 3 each at 1,2,3,4 and 5 years.
Pests
Birds are probably the major pest risk. Covering the bushes with fine mesh netting or light fabric protects against all but ground entry. Suspending aluminum pie tins above the plants so they twist and ding in the breeze can also be effective.
Be sure to pick ripe berries promptly to avoid drosophila infestations. Note though that berries don’t reach full ripeness for 5-7 days after turning blue. Harvest timing is critical.
Pollination:
Photo: George Hoffman, Ph.D.
Healthy blueberry bushes generate thousands of buds, each with a cluster of 16 flowers, each flower a potential berry. Each berry has many seeds, nearly all of which must be individually fertilized for a healthy, normal sized berry to develop, so active pollination is essential. Blueberry pollen is sticky, but relatively heavy and not likely to reach the stigma without insect intervention. Native bees, including bumble and solitary bees are potential pollinators. Commercial growers often bring in honey bees to augment natives. The insects are attracted by scent and sweet nectar in at the base of the stigma. Nectar and pollen are both food sources. Not all flowers in a cluster open at the same time, but when a flower opens, the pollen and stigma are ready for transfer to take place. Pollination must happen within a few days for a berry to form.
It Takes a Commitment
Photo: Stephy cupcake
Successfully growing blueberries, like most good things in life, requires a commitment. From picking the right varieties to managing soil pH and drainage to pruning to pest management. But there has been a lot of work done to provide cultivars that will succeed in our environment and helping us understand the important aspects of caring for them to best assure good berry production. For gardeners willing to take the plunge, the reward can be 20 years of enjoyment of a tasty, healthy, recently anointed superfood.
Sources:
https://pubs.ext.vt.edu/438/438-103/438-103.html
http://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/426/426-840/426-840_pdf.pdf
https://hgic.clemson.edu/factsheet/changing-the-ph-of-your-soil/
https://chatham.ces.ncsu.edu/2016/03/how-do-i-grow-blueberries/
https://ohioline.osu.edu/factsheet/HYG-1422
https://entomology.ces.ncsu.edu/small-fruit-insect-biology-management/blueberry-pollinators/
Blue in the Sun
This article will present several sun-loving plants in various shades of blue that capture the imagination: sky blue, midnight blue, periwinkle blue, blue mist, blue ice, storm cloud, and indigo. To enjoy the beauty of blue throughout the gardening season, consider a spring-bloomer, a late spring/early summer bloomer, and then a late summer/fall bloomer. The first two plants are native to North America; the last is a nonnative from Asia.
AMSONIA
Amsonia, commonly called blue star, is a genus of about 20 species named in honor of 18th century Virginia physician, Dr. Charles Amson. It is native primarily to North America with one species in East Asia and another in the eastern Mediterranean. This article will focus on those species native to the U.S. This clump-forming perennial has narrow, alternate leaves and clusters of blue, 5-petaled flowers. The light blue flowers are followed by elongated, pod-like fruits containing hard, black seeds which can be used for propagation. Amsonia offers three-season interest: showy, long-lasting blooms in spring (mostly in May); threadlike green foliage in summer; and yellow foliage in fall.
Of the family Apocynaceae (dogbane), members typically have milky or viscous sap that can be loaded with highly toxic alkaloids. The latex sap is mildly irritating and is not considered to be harmful to humans, although people with latex allergies are advised to wear gloves. The sap makes the plant unappealing to foraging deer, rabbits, and many garden pests.
Other members of the Apocynaceae family include periwinkle (Vinca), oleander (Nerium oleander), and the reclassified milkweed family (Asclepiadoideae), now considered a subfamily of the dogbane family.
Growing Conditions
Although it prefers moist, loamy soil, this plant can be grown in most well-drained soils, tolerating clay soils very well. Once established, it is drought resistant. Amsonia thrives in full sun to part shade. When grown in full sun, plants often require no pruning or staking. When grown in partial shade and/or in rich soils, plants tend to become more open and floppy and often require staking or pruning. Full sun promotes a brighter golden foliage color in the fall. Shade protection from the midday sun in hot climates promotes longer-lasting blooms. For a neater appearance, particularly for shade-grown plants, consider cutting back stems by 1/2 to 1/3 after flowering to promote bushy growth and a more rounded foliage mound. The dwarf cultivars do not require staking or cutting back. Moderately drought-tolerant once established, this is a low maintenance, easy-to-grow, long-lived plant not subject to disease or pest problems.
Pollinators
Many insects enjoy the nectar of amsonia flowers, especially long-tongued insects such as carpenter bees, hummingbird moths, and butterflies. Ruby-throated hummingbirds are also attracted to the nectar.
Uses
The range of plant sizes makes amsonia a versatile choice in the garden. Tidy foliage and a striking vase-shaped growth habit allow bluestar to perform well as either an accent plant or in mass plantings. It is an excellent addition to a pollinator garden, native garden, deer-resistant garden, butterfly nectar garden, cottage garden, water-wise landscape, low maintenance planting, meadow, or prairie garden. Smaller varieties work well in containers.
Propagation
The plant can be propagated from stem cuttings taken after flowering. Propagation by seed is possible, but lengthy. It first requires a stratification process. Seeds then take about 10 weeks to sprout and seedlings may not be ready to transplant for about 20 weeks. Although plants rarely need to be divided for overcrowding or rejuvenation, propagation by division is fairly easy. Divide plants in late summer or early fall to ensure that the divided plants develop roots before the ground freezes. Cover with a winter mulch to prevent newly divided plants from heaving during the freeze-and-thaw cycles.
Amsonia Species
Amsonia tabernaemontana Photo: Gail and Hal Clark
Amsonia tabernaemontana
Commonly called eastern blue star, bluestar, blue dogbane, or willow amsonia, this native is found in central and eastern U.S. from New York to Florida. It has light blue flowers. Dense foliage is lime green when it first appears and then turns dark green. The lance-shaped foliage is coarser and larger than that of A. hubrichtii.
Cultivars
A. tabernaemontana ‘Short Stack’ is a dwarf cultivar that grows to only 10-12” tall and 18” wide. It has sky-blue flowers. This cultivar may be subject to rust.
A. tabernaemontana ‘Storm Cloud’ features near-black stems with silver-veined dark green leaves in spring which lighten to olive green by summer. Light periwinkle-blue flowers bloom from late spring to early summer, often with some rebloom thereafter. It may be subject to rust.
Amsonia ‘Blue Ice’ is very similar in appearance to A. tabernaemontana, except that it is much more compact, growing to 1.5’ tall and wide. Its flowers are dark lavender-blue. In a Chicago Botanical Garden plant evaluation, ‘Blue Ice’ was awarded a 4-star rating. Although ‘Blue Ice’ was reportedly discovered growing with A. tabernaemontana seedlings in a greenhouse at White Flower Farm, the parentage has apparently not yet been definitively determined.
Amsonia ‘Seaford Skies’ is a bluestar hybrid (A. hubrectii x A. tabernaemontana) that was discovered growing in a private garden in Seaford, Virginia. Averaging 2-4’ tall and 2-3’ wide, it can grow as tall as 5 feet. It features sky blue flowers atop 36” erect stems.
A. tabernaemontana var. salicifolia
Commonly called bluestar, this perennial is native to the southeastern U.S. in zones 3-9, so it is somewhat winter hardier than other amsonias. It prefers moist, loamy soils but can also tolerate clay. It has some drought resistance. Its flowers are light blue with white throats.
A. illustris
Commonly called Ozark bluestar or shining blue star, this Missouri native has light blue flowers. Although very similar in appearance to A. tabernaemontana, the leaves of A. illustris are shinier, thicker, and more leathery and the seed pods are pendant. The plant grows 2-3’ tall and 1-1.5’ wide.
A. hubrichtii
Amsonia hubrichtii Photo: peganum, Wikimedia Commons
Commonly called bluestar, Arkansas amsonia or Hubricht’s amsonia, this uncommon perennial is native to central Arkansas. The feathery foliage of A. hubrichtii is significantly different from the broad leaves of A. tabernaemontana. It is also narrower and more thread-like than the needle-like leaves of A. ciliata and lacks that species’ conspicuous hairiness. Powdery-blue flowers appear in April to May.
Specific epithet is in honor of Leslie Hubricht, an American biologist and malacologist (mollusks) who first discovered this amsonia species growing in the wild in the early 1940s. Mr. Hubricht worked as an assistant at the Missouri Botanical Gardens from 1936 to 1943.
A. ciliata
Commonly called blue star, fringed blue star, or downy amsonia, this perennial is native to the southeastern U.S. The specific epithet, ciliate, means hairy-margined in reference to the fringe of hairs found on new leaves and plant stems. It has narrow almost needle-like green leaves. Its flowers are pale blue. Consider cutting stems to 8-10” after flowering.
BAPTISIA AUSTRALIS
Another beautiful, shrubby, spring-blooming perennial with purple-blue blossoms is commonly called blue false indigo. It is native to the eastern and mid-western areas of the United States. Depending on the cultivar, blue false indigo typically blooms for about three to six weeks in late spring to early summer. Attractive blue-green, trifoliate foliage adds pleasing color and texture to the landscape even after the flowers have long disappeared. It grows 3-4’ tall and wide so provide ample room in your garden. This sun-loving plant is low maintenance, has few pests and diseases, and is not bothered by deer and rabbits! It also provides nectar to a variety of butterflies and pollinators. For detailed information on adding this stunning plant to your garden, see the May 2015 issue of The Garden Shed.
Batisia australis Photo: Jean-Pol GRANDMONT, Wikimedia commons
There is also a smaller version, Baptisia australis var minor, that grows 1.5-2’ tall and wide. Var. minor appears to differ from the species primarily by being a smaller plant with shorter stems and shorter leaves but larger flowers. The average inflorescence is about 18” long. The bloom period is in late May-June and lasts for about 3 weeks.
For plant trials and comparative results on various cultivars of Baptisia australis, refer to the Mt. Cuba Center. Baptisia australis is currently undergoing plant evaluation trials at the Chicago Botanic Garden.
CARYOPTERIS
Native to eastern and southern Asia, of the family Lamiacaea (mint), most plants in the genus Caryopteris are woody shrubs. Though several Caryopteris species are grown in botanical gardens as ornamental plants, the species have largely been superseded in home gardens by the hybrid Caryopteris × clandonensis (C. incana × C. mongholica). The hybrid, commonly called bluebeard, blue spirea or blue mist, originated from a chance seedling in an English garden in 1933. It was first introduced to the United States in the 1960s and soon became a garden favorite. Although not listed as invasive on the USDA Plants Database, Introduced, Invasive, and Noxious Plants, it should be watched for invasive properties because of its more recent introduction into U.S. landscapes.
Caryopteris x clandonensis Photo: Andrew Zarkikh, NCSU
Bluebeard is a low-mounded, deciduous shrub with an average height and spread of 2-3’. It is valued for its aromatic foliage and fragrant flowers which are said to resemble clouds of blue smoke or mist from late summer to early fall. The lance-shaped leaves are opposite, gray-green, and have serrated margins. Some cultivars offer variegated foliage. Roots are cold-hardy to zone 5; expect winter die-back of woody stems in climates colder than USDA Zone 7.
Caryopteris should be planted in moist, well-drained soil and exposed to full sun in order to maximize blooms. It can happily exist in light shade where it is more drought tolerant although it will not bloom quite as prolifically. Over-watering will cause root rot. Too much fertilizer may result in vigorous growth but fewer blooms. Because the flowers appear on new growth it is best to cut the shrub back to at least one-third or one-half its height in early spring. This pruning will encourage a more robust blooming season each year and serve to keep the plant’s growth habit well formed. Bumblebees, butterflies and hummingbirds are attracted to the flowers. Its aromatic leaves make it unappealing to both deer and rabbits!
Uses
Caryopteris x clandonensis in cottage garden Photo: Gail and Hal Clark
Because of its compact size and mounded habitat, caryopteris adds structure to the garden as a specimen plant. Its lance-shaped foliage contrasts nicely with broadleaf plants and its profusion of blooms offers a striking focal point. The accompanying photo shows C. x clandonensis ‘Longwood Blue’ in a cottage garden with the annual, Zinnia elegans ‘Tudor’™, and perennials: Rosa ‘Radyod’ BLUSHIING KNOCKOUT; Hylotelephium ‘Herbstfreude’ AUTUMN JOY (stonecrop); and Dianthus ‘Feuerhexe’ FIREWITCH.
Caryopteris x clandonensis Cultivars
‘Dark Knight’ has deep bluish-purple flowers; ovate to lance-shaped, dull green leaves are silvery below.
‘Longwood Blue’ is a taller cultivar which may reach a height of 4′. It features a profuse, shrub-covering bloom of violet-blue flowers.
‘Arthur Simmonds’ was judged to be the hardiest cultivar of Caryopteris in the Ornamental Plant Evaluation trials at the Chicago Botanic Garden. It has violet-blue flowers.
‘Blue Mist’ has powder-blue flowers.
‘Summer Sorbet’ is a variegated cultivar that is noted for its green leaves with gold edging and its blue flowers.
C. × clandonensis ‘Durio’ Pink Chablis™ is prized as a landscape addition for its pink flowers unique to bluebeards and for its attractiveness to insect pollinators. Discovered in 1998 as a chance seedling in a Louisiana garden, it has been the subject of studies by the Dept. of Defense Deployed War-Fighter Protection (DWFP) research program. The essential oils of Pink Chablis™ have been investigated for chemical composition and bioactivity as a repellent and larvicide against the yellow fever mosquito (Sedes aegypti). It exhibited mild repellency compared to DEET and weak activitiy as a mosquito larvicide. The essential oils of its parent species have also been studied for use as insect repellents.
SUMMARY
Each of these three sun-loving plants offers: a substantial shrubby presence in the garden; attractive foliage with interesting texture; resistance to deer and rabbits; and low susceptibility to pests and diseases. They are all good candidates for pollinator gardens since they attract butterflies, bees, and hummingbirds. The availability of cultivars offers a wide range of “blueness” that complements many other flower colors including pinks, yellows, whites, and reds. In addition, using a combination of all three plants will promote bloom for a good portion of early spring through fall!
SOURCES
Specific Plant Information by Name, Missouri Botanical Garden Plant Finder, http://www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx
Specific Plant Information by Name, Lady Bird Johnson Wildflower Center Plant Database, https://www.wildflower.org/plants/
Piedmont Natives – Plant Database, https://www.albemarle.org/nativeplants/
Bluestar, Amsonia Tabernaemontana, Illinois Wildlife Federation, https://www.illinoiswildflowers.info/woodland/plants/bluestar.htm
Bluestar, Ozarkedge, https://ozarkedgewildflowers.com/spring-wildflowers/blue-star-or-amsonia-amsonia-tabernaemontana/
Amsonia ‘Blue Ice’, Plant Evaluation, Chicago Botanic Garden, http://perennialsinfocus.com/snapshots-a-d/
Willowleaf bluestar, Amsonia tabernaemontana, https://wimastergardener.org/article/willowleaf-bluestar-amsonia-tabernaemontana/
“Eastern Blue Star,” The Morton Arboretum, https://www.mortonarb.org/trees-plants/tree-plant-descriptions/eastern-blue-star
Plant Evaluation, Chicago Botanic Garden, https://www.chicagobotanic.org/collections/ornamental_plant_research/plant_evaluation
“Plant Evaluation Notes: An Evaluation Study of Hardy Amsonia,” https://www.chicagobotanic.org/downloads/planteval_notes/no18_amsonia.pdf
“Baptisia australis: Both Beautiful and Indestructible!” The Garden Shed, https://pmgarchives.com/article/baptisia-both-beautiful-and-indestructible/
Baptisia, Mt. Cuba Center, https://mtcubacenter.org/trials/baptisia/
Baptisia australis var.minor, Mt. Cuba Center, https://mtcubacenter.org/trials/baptisia/baptisia-australis-var-minor/
USDA Plants Database, Introduced, Invasive, and Noxious Plants, https://plants.usda.gov/core/profile?symbol=CACL7
“April: Blue Mist Spirea Caryopteris x cland0nensis and its Cultivars, Santa Fe Botanical Garden, https://santafebotanicalgarden.org/april-2013/
For insect repellent research, google: C. x clandonensis ‘Durio’ Pink Chablis™ Research Gate
The Ornamental Garden in April
Two main activities, aside from compulsively running out to neighborhood nurseries to see what plants have arrived, capture the attention of gardeners in April — pruning ornamental shrubs and dividing perennial plants.
Before looking at these two activities, let’s consider other early-spring tasks that will help “set the stage” for a season-long ornamental display. At the threshold of the growing season, optimism runs high and digging in the dirt—even weeding—is a pleasure.
- Weed out the winter broadleaf weeds you missed in March. The University of Illinois Extension’s on-line publication on Weed Identification contains a number of useful close-up photos of weeds.
- Edge your beds and top-dress with a one-inch layer of compost, being careful not to disturb signs of emerging plants. After plants emerge a few inches more, add about 2 inches of mulch or ground leaves for weed control and moisture protection.
- Consider adding low-growing, native plants or sedges in bare areas where you ordinarily mulch, such as between shrubs in foundation plantings, or along paths.
- Identify spots where you’d like to add daffodils or other spring-blooming bulbs. Tent stakes work well as markers and can be a helpful physical aid to pictures.
- Sow seeds directly outside after checking planting directions on seed packets. For example, some seeds should not be planted until after the last frost; some can be planted 1-2 weeks before the last average frost date.
When is the average last frost date? Albemarle County and its surrounds are on the borders of the Piedmont and Mountain regions of Virginia. VCE (Virginia Cooperative Extension) Publication 426-331 puts Albemarle County in the Mountain region which has an average final frost date of May 10-15. On the other hand, USDA places Albemarle in Hardiness Zone 7a which specifies a final frost date of April 20-30. The University of VA Climatology Office is more in line with the April targets.
- For seeds started indoors, harden off seedlings before planting in open ground to prevent transplant shock. Place them in a shady location initially and bring them indoors at night if temperatures are predicted to drop below 50°F. For advice on transplanting seedlings, see the Virginia Cooperative Extension article, “Plant Propagation from Seed.”
- Remove faded flowers from daffodils, tulips and hyacinths, letting the foliage die naturally. Don’t braid or tie up the foliage since this could interfere with photosynthesis for food production. If your daffodils have become crowded and aren’t producing as many flowers as in past years, they need to be divided. Mark the location of the clump with a marker such as a golf tee, plastic knife, or wooden stick so that you can find it later in the summer after the foliage has died back. Make a note to dig up and separate the bulbs in July. (TIP: Use a different type of marker for dividing bulbs than you use for identifying empty spots you want to fill.)
- Prune hybrid roses when bud growth starts in early spring. When making cuts, prune back to just above an outward-facing bud. See the Clemson Cooperative Extension, “Pruning Roses.”
- Install stakes or ring-type supports for peonies.
- If a frost is forecast, protect tender new growth with row covers, old sheets, cardboard, or even layers of newspaper. Remove the coverings the next morning to prevent “cooking” your plants as the day warms up. Deutzia is one example of a spring-blooming shrub that will appreciate frost protection.
- Move your houseplants outside once night-time temperatures consistently stay at 50° F. or higher. Repot any root-bound plants into slightly larger pots. Fertilize with a slow-release fertilizer. Place the plants in a shady area initially so that they can gradually acclimate to being outside.
PRUNING
As a rule, shrubs that bloom in spring bloom on old wood and should be pruned after blooming. Many spring–flowering shrubs, such as azaleas, set next-year’s flower buds soon after they finish blooming in the current year. Therefore as a general rule, shrubs that flower before June 15 should be pruned soon after flowering. Examples of such spring-blooming plants are: azalea, deutzia (Deutzia gracilis), fothergilla (Fothergilla gardenia and F. major), Korean lilac (Syringa meyeri), Bridalwreath spirea (Spirea prunifolia).
Summer-to-fall-blooming shrubs bloom on new wood and should be pruned in late winter to early spring. This leaves plenty of time for the plant to recover from pruning and still create flower buds for the bloom season. Examples of these shrubs include: abellia, beautyberry (Callicarpa Americana), Hydrangea macrophylla (mophead), and Japanese spirea (Spirea japonica). In general, the time has now passed for pruning these shrubs. You can still prune dead wood or a few stray branches that are insulting your aesthetics, but resist full-scale pruning that will ruin this season’s blooms.
For more information on pruning, see The Garden Shed article, “When to Prune.” For a pruning schedule of specific shrubs, see the Virginia Cooperative Extension (VCE) publication, “A Guide to Successful Pruning, Shrub Pruning Calendar.”
Plant Division
Fortunately, there is also a general rule for plant division: divide late-summer or fall-blooming perennials in the spring, and divide spring/early summer bloomers in the fall. A sampling of plants that should be divided in spring includes:
- Aster
- Blanket Flower (Gaillardia grandiflora)
- Canna lilies
- Chrysanthemum
- Lily of the Valley (Convallaria majalis)
- Most ornamental grasses
Some plants can be successfully divided in either spring or fall. A sampling of such perennials include:
- Agapanthus
- Astilbe
- Beebalm (Monarda)
- Bellflower (Campanula)
- Cranesbill (Geranium)
- Garden Phlox (Phlox paniculata)
- Hosta
- Lamb’s ears (Stachys byzantina)
- Purple Coneflower (Echinacea)
- Red hot poker (Kniphofia)
- Black-eyed Susan (Rudbeckia fulgida)
- Tickseed (Coreopsis)
- Yarrow (Achillea)
For a list of when specific perennials should be divided, see the Virginia Cooperative Extension article, “Dividing Perennials.” This publication also includes a list of plants that should NOT be divided.
For advice on how to divide, see Virginia Cooperative Extension Publication 426-203, Perennials: Culture, Maintenance and Propagation and The Garden Shed, Tasks and Tips April 2017.
For other April to-do lists, see The Garden Shed past issues from 2015, 2016, 2107, and 2018.
LAWN CARE SPRING QUICK TIPS
- Soil test before applying fertilizer. A soil test is the only way to determine if the soil needs lime, phosphorus (P) or potassium (K). Apply nutrients as recommended by a soil test and you’ll be taking a huge first step towards protecting water quality. See the April 2015 issue of The Garden Shed for an article on “Soil Testing.”
- Mow the lawn after it has grown at least two inches. The roots are being renewed in the spring and grass needs vigorous top growth initially. Set lawn mowers at the highest height early in the season.
- Topdress low spots and finish overseeding thin or bare patches.
- Apply crabgrass preventer before April 15. Do not apply to areas that will be seeded.
- Aerate turf if soil is compacted.
For a list of VCE publications on lawn care, including fertilization schedules, weed control, seeding, and overseeding, see VCE Tags.
INVASIVE SPOTLIGHT: WINEBERRY
Although not on the Terrible Twelve list of invasives identified by Blue Ridge PRISM (Partnership for Regional Invasive Species Management), this month’s invasive spotlight is on wineberry (Rubus phoenicolasius), another nonnative invasive in our area (and a scourge in my home landscape, in particular). Early spring is an effective time to begin a wineberry eradication project, especially when the soil is moist.
Wineberry (Rubus phoenicolasius) Photo: Susan Martin
A member of the family Roseacea, the plant was introduced into the United States from Asia in 1890 as breeding stock for Rubus (blackberry and raspberry) cultivars and is still used today by berry breeders. Wineberry has a wide range of tolerance for light, soil type, and moisture level, and is hardy to USDA Zone 5 (annual minimum temperatures to -20 ºF). It is considered invasive in Maryland, Pennsylvania, Tennessee, Virginia, North Carolina, West Virginia, and the District of Columbia. It is listed as a prohibited invasive in NY.
The entire plant is covered in tiny, reddish hairs and sharp spines. The compound leaves are made up of three heart-shaped, toothed leaflets. The leaves alternate along the stem and are green on top, white on the underside. The plant grows in long shoots called canes up to 9’ long, which can re-root at the tips when they touch the ground. Wineberries are perennial; while the canes each live two years, the plant produces new canes every year. Leaves are produced in April; white, five-petaled flowers bloom in May; and red raspberry-like fruit appears from late June to August. The glandular-hairy calyx lobes envelop the developing fruits and keep them covered until almost ripe. Leaves drop in late November. Although its berries are a source of food for wildlife, wineberry’s rapid growth poses a threat to native plants by creating dense patches that crowd out desirable species. Its rapid spread creates spiny, impenetrable thickets that reduce an area’s value for wildlife habitat and for recreation.
Treatment
This nonnative invasive reproduces clonally from root nodes, tip-rooting, and by seeds dispersed by birds, reptiles, and mammals. Wineberry is difficult to control and should never be deliberately planted. Small infestations can be handled by pulling individual plants—if the soil is moist and workable—or by digging them out with a shovel or spading fork. Where accessible, canes can be mowed with brush-type equipment. You can also cut the canes close to the ground and treat the open cut with an herbicide. In all likelihood, removal practices will need to be repeated. As with the treatment of any invasive, try to attack the invader before it becomes entrenched.
INVASIVE SOURCES:
New York Invasive Species Information: Wineberry, http://nyis.info/invasive_species/wineberry/
USDA Fire Effects Information System, Rubus Phoenicolasius, https://www.fs.fed.us/database/feis/plants/shrub/rubpho/all.html
Wine raspberry, Invasive Plant Atlas, https://www.invasiveplantatlas.org/subject.html?sub=3072
Blue Ridge PRISM, https://blueridgeprism.org/
Upcoming Events
April 2019
Blue Ridge PRISM Spring Invasive Plant Workshop
Tuesday, April 9, @ 6:30-8:30 P.M.
Albemarle High School in Charlottesville
Through the Garden Gate Tour
Saturday, April 13, @10:00 A.M-12:00 P.M.
Through the Garden Gate, the 18th annual series of visits to local gardens in and around the Charlottesville area will begin on April 13, 2019 with a visit to Pam Sorenson’s Garden at 928 Rugby Road in Charlottesville, hosted by the Piedmont Master Gardeners and the Dogwood Garden Club. The garden is the result of a 10-year collaboration between Pam Sorenson and landscape designer Cole Burrell. The one-acre property features enormous magnolia and holly trees, a series of terraces defined by brick walls, a patio and fountain, a boxwood parterre garden, and a rock garden with three interconnecting pools. For more details, visit http://pmgarchives.com/events/ or call 434-872-4581. Admission is $5.00.
Garden Basics: Vegetable Pests and Diseases
Prevent common pests and diseases and treat them safely and effectively when they arrive.
Ivy Creek Natural Area Monthly Plant Walk
Saturday, April 20 @9:00-11:00 A.M.
Led by a member of the Jefferson Chapter of the Virginia Native Plant Society
Meet at the Kiosk by the parking lot
Ivy Creek Natural Area, 1780 Earlysville Rd., Earlysville
Annual Plant Sale of the Jefferson Chapter of the Virginia Native Plant Society
Saturday, April 27 @1:00-3:00 P.M.
Ivy Creek Natural Area, 1780 Earlysville Rd., Earlysville
Spring Open House, Thomas Jefferson Center for Historic Plants
Saturday, April 27 @ 10:00 A.M.-2:00 P.M.
Tufton Farms
Historic Garden Week /Albemarle County
Sunday, April 28 @10:00A.M.-4:00 P.M.
The tour features five properties west of Charlottesville in Ivy.
Saturday, May 4 → ANNUAL PLANT SALE
Presented by Piedmont Master Gardeners & Charlottesville Area Tree Stewards
10:00 am — 2:00 pm
NEW LOCATION! Look for the tent at The Shops at Stonefield, 2100 Hydraulic Road, Charlottesville
Mark your calendar now — and be sure to note the new location!
The Green Elephant section of the sale has been growing in size and popularity over the last few years. Consider donating your clean, no-longer-needed garden items: decorative pots (no floral vases), garden books (no magazines), floral prints, tools in good shape and outdoor decorative garden items (including gnomes and flamingos!) are all appreciated. Contact lilibetcoe@comcast.net about where and when to drop off donated items.
Fried Zucchini Chili
Here’s my favorite vegetarian dish, which is good either hot like a champion chili or cold as a sinful gazpacho. When I make this, I usually triple the amounts only because I eat two heaping bowls in between the time I finish making it and the deep hypnosis sleep I enjoy afterwards. Yes, dear gardening gurus, it’s THAT good! This serves 2-3 normal people or one teenage athlete. In addition I’ve listed some tactics to adapt this feast in ways that allows you to fool your audience into believing you’re the next Emeril or Giada, when you’re actually just making the same damn thing over and over again. This works best in a saute pan but it’s perfectly kosher to employ your enchanted Crock Pot instead. If you overcook it, simply put the spoons away and break out the tortilla chips. Satisfaction guaranteed or your money back.
Fried Zucchini Chili
¼ cup Olive oil
2-3 Garlic cloves: crushed or minced
2-3 diced Zucchini squash
2 cans Garbanzo beans (drained)
1 can Diced Tomatoes (drained)
Kosher Salt & Cracked Black Pepper to taste
1 Lime (juice)
1. Heat the olive oil in a large sauce pan or stew pot on medium high heat.
2. Add garlic either crushed whole or minced up. Allow it to sweat out.
3. When the garlic starts to color slightly, add the diced zucchini and stir to coat it in the oil.
4. Fry the zucchini until translucent then add a can of garbanzo beans.
5. Give the garbanzos 5 minutes to fry up & stir a few times.
6. Drain the can of diced tomatoes, then add to the pan.
7. Reduce heat to medium low, stir, and simmer for 5 minutes uncovered
8. Add the juice of one lime.
9. Add the salt & pepper to taste
10. God Bless America
Adaptation ideas:
- Add the lime zest for more bite
- Substitute garlic with ginger, shallots, pearl onions, olives, or capers
- Replace the lime with other fruit juice, wine, cider, or stock to change the flavor
- Substitute garbanzos with navy, Lima, or cranberry beans
- Replace tomatoes with or add roasted red bell peppers
- Substitute zucchini with sweet potato, eggplant, summer/butternut/spaghetti squash, or pumpkin
- Replace olive oil with coconut, avocado, lemon oil, or clarified butter
- Spice options: coriander/cilantro, nutmeg, bay, basil, sage, mint, or thyme