What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

Why Some Crapemyrtles Do Not Flower

Posted by Hugh on September 23rd, 2013

Sparse Flowering Caused By Multiple Factors

There are several probable reasons why your crape myrtle did not flower this summer. The two leading reasons are lack of adequate daily sunlight and planting depth. Crape myrtles should be planted in full sun. They don’t flower well in locations receiving less than 6 hours of direct sunlight each day.

If the leaves are being heavily attacked by aphids or fungal diseases like Cercospora leaf spot and powdery mildew, the plant is not producing enough carbohydrates (food) to initiate flower buds. Also, the aphids feeding may be inflicting damage to the flower buds.

“Crape Murder” pruning after new spring growth has started can delay or completely eliminate flowering. Overpruning often promotes excessive growth at the expense of flowering. In fact, crape myrtles require little annual pruning. In most years pruning on crape myrtles should be mostly cosmetic, such as to cut off a dead or crossing branch or to remove last year’s old seed heads.

Poorly drained (too wet) soils is another cause. Unusually heavy amounts of rain may retard or completely eliminate flowering. Crape myrtles must be planted on a well-drained site. Heavy rainfalls also leach nutrients out of the ground.

Over-applying nitrogen-based fertilizers may push your crape myrtle into vegetative growth and few, if any, flowers may develop.

Crape myrtles do not tolerate deep planting. The upper-most (surface) roots should be at ground-level or an inch or two above, never several inches below the soil line. When planted too deep, the roots don’t get enough oxygen, leading to reduced growth and flowering.

Crapemyrtles can recover from deep planting over several years. They must regenerate a new root system closer to the surface. Removing mulch piled up around the base of the plant will help roots breathe.

Special Thanks to: Dr. Gary Knox at North Florida Research Center

Beautyberry Deservedly Becoming More Popular

Posted by Hugh on September 20th, 2013

Vibrant Purple Berries of American Beautyberry

The stunning purple berries of beautyberry (Callicarpa spp.) are eye-catching in late summer. White fruited varieties are also sold, but the purple forms are most popular. This 6-8 foot shrub has medium green, 3-5 inch long foliage spring thru summer. Autumn leaf color adds little, the deciduous leaves turning purple to pale yellow, shriveling, and abcising.

The purple fruit clusters are electifying, perhaps nature at its gaudiest. Individual fruits measure 1/4 inch or less in size, and clustered together around the stems, creating quite a show. Numerous species of birds feed on the fruits, either from the Japanese (C. dichotima) and native (C. americana) forms.

Clusters of pink or lavender colored flowers open in mid-July, and are mostly unnoticed because of their small size; flowers are somewhat hidden within the thick foliage.

Grow beautyberry so the magnificent late summer fruit display may be easily seen. Beautyberry thrives in full sun to partial shade (as little as 1 hour of sunlight needed). Its soil needs are average, although beautyberry grows and fruits best under full day sun and in moist well drained soils. Mulch plants to reduce weeds and to conserve soil moisture.

Prune to remove winter injured branches (in USDA zone 5) and to open this dense growing shrub to additional sunlight. Heavier pruning may be required to control its wild-like nature further south. All pruning should be completed by mid-spring. Flowers and fruits form on new season’s growth.

Viable seeds are dispersed into your landscape and your neighbors’ yards as well. Invasiveness is currently unproven , so plant the native species just in case. The foliage is rarely troubled by disease or pest problems.

Better Blackberry Varieties Available

Posted by Hugh on September 18th, 2013

Trellised blackberries beginning to fruit

Growing Blackberries

Blackberries (Rubus spp.) are among the easiest fruit crops to grow in the Southern Appalachian region (USDA hardiness zones 5 and 7), but are not as hardy as raspberries.

A blackberry planting has a productive life between 8-10 years. A sturdy trellis system, composed of strong posts and wire, will make harvest chores easier. You can expect a partial crop the second year after planting and full crops in year three and beyond. Blackberry culture is similar for raspberries.

Select and prepare the planting site. Blackberries prefer open full sun and grow best in well-drained, sandy loam soils rich in organic matter. Avoid low ground areas which suffer from poor air and soil drainage. An available water supply is necessary for maximum berry yields and size.

Soil preparation is most important for multi-year harvests. Test your soil to determine its pH and fertility levels. Blackberries prefer a acidic soil pH range between 5.6 to 6.2. Most county Extension offices offer soil testing services for a small fee.

Based on your soil report, add generous amounts of organic matter and well-rotted manure to garden soil. Unless your soil analysis states differently, broadcast 20 to 25 pounds of 10-10-10 fertilizer per 1,000 square feet over the planting area.

Blackberries require good field sanitation which includes annual cane pruning. They have few disease and pest problems. Weeds will be a common problem as they attract potentially serious pests. Mulching helps reduce weed infestations and conserve soil moisture.

Select virus-free, high yielding, and great tasting varieties. Blackberry Varieties* (by order of ripening):

Thorned:

Choctaw –small berry, high yields
Chickasaw –large berries
Kiowa –very large berries
Shawnee –high yields

Thornless Erect:

Natchez –large berries
Arapaho –low yields
Ouachita –high sugar levels
Navaho –firm berries
Apache –large berries, white drupelets

Thornless Semi-erect:

Chester –very high yields, late ripening
Triple Crown

* Blackberry varieties recommended by Dr. David Lockwood, Fruit Specialist with the Universities of Tennessee and Georgia

‘Guacamole’ Hosta An Outstanding Garden Performer

Posted by Hugh on September 14th, 2013

'Guacamole' Hosta Flowers in August Garden

Guacamole (Hosta plantaginea ‘Guacamole’) is rated one of the top performing hostas in the Northeast and mid-South U.S. gardens. Guacamole is a hybrid and one of its parents is H. plantaginea ‘Fragrant Bouquet’. In 2002 it was selected Hosta of the Year by the American Hosta Society.

Guacamole is a medium-sized hosta. It matches its catalog description within three years. Guacamole grows 1 ½ feet tall and three or more feet wide with a mound-like habit. New spring leaves unfurl with apple green centers and dark bluish-green margins. Summer foliage darkens to avocado centers and medium green margins. The high gloss leaves average 10 inches in length and 8 inches in width. Leaf venation is moderate at best.

In August multiple scapes of white funnel-shaped flowers rise 36 inches tall above avocado green foliage. Yes, the flowers are fragrant, but their scent is never overwhelming.

Hostas prefer a moist, compost-rich, well-drained soil. They are the most popular shade perennial, yet many handle full sun well under regular irrigation. In northerly areas (USDA hardiness zones 4-5) with cooler summer, most hardy cultivars grow in full sun. While mostly free of diseases and pests, many cultivars are susceptible to foliar damage from slugs and snails. Deer are also a serious menace.

Hostas should be divided every 5 years, either early spring or mid-autumn. In early spring wait for shoots to poke up, but before leaves unfurl. As leaves decline in the fall, dig up the entire clump and divide with a sharp knife.

Guacamole was introduced by Solberg in 1994.

Aster ‘Raydon’s Favorite’ Is Spectacular Autumn Bloomer

Posted by Hugh on September 11th, 2013

Aster 'Raydon's Favorite' in late October

Aster Raydon’s Favorite (Symphyotrichum oblongifolium ‘Raydon’s Favorite’) is one of our most reliable native perennial asters. This aromatic aster blooms in mid-autumn, covered with 1 ½ inch wide blue-purple daisy-like flowers with yellow centers.

Butterflies and bumble bees are frequent visitors to this aster in my October garden. Night temps in the mid-twenties don’t injure the flowers. Leaves and stems emit a minty, aromatic aroma when crushed. Raydon’s Favorite also is an excellent cutflower (U.S. hardiness zones 3 to 8).

Raydon’s Favorite forms a compact mounding shrub, growing 3 to 4 feet tall after 2-3 years, slightly wider than high. To produce more flowers and improve plant density and uniformity, prune this aster back by half in mid-July and allow it to re-grow. Feed plants again with a water-soluble fertilizer such as Miracle-Gro®, Jack’s® or Schultz® according to package directions.

Grow in full sun and in average garden soil; it flourishes in a compost – rich soil. Established plants are exceptionally drought tolerance. Feed at planting time or in early spring with a slow-release fertilizer such as Osmocote®. After flowering is completed, cut back and gather up branches to reduce seed dispersal into other parts of the garden.

Asters need to be divided once every 3 to 4 years to keep them growing vigorously. Raydon’s Favorite appears to be disease or pest free. Plant(s) should be divided in either spring or fall or from cuttings taken in early summer.

Raydon’s Favorite began appearing in garden centers about 1995, introduced by Allen Bush from a plant he received from Raydon Alexander in San Antonio, TX, from a plant he acquired on Lookout Mountain in Tennessee.

Heirloom Mums Are Back!

Posted by Hugh on September 8th, 2013

Dendranthemum 'Ryan Gainey'

Bring back heirloom or “old-fashioned” mum varieties into your autumn garden! These varieties tend to bloom very late in the fall and tend to be hardier (USDA hardiness zone 5). Four of the best heirlooms are:

‘Clara Curtis’ – deep pink, daisy-like blooms

‘Mary Stoker’- peachy yellow blooms

‘Sheffield’ (aka ‘Sheffield Pink’) – light pink

‘Ryan’s Pink’ – bright pink daisy blooms with yellow centers.

If you want to grow heirloom mums, you may be purchased plants from e-commerce nurseries on-line in early spring. Plant them in full sun and in moist well-drained soil where they should be nurtured through the summer months. Avoid planting them in areas where street and house lights will shine on them at night. Mums bloom poorly without a full night of darkness.

Feed once at spring planting time with a slow-release fertilizer. As an alternative, feed with a water-soluble fertilizer such as Miracle-Gro®, Daniels®, or Jack’s Classic® twice monthly until buds form or through the end of August.

From late spring until mid-July, pinch growing tips back 2-3 inches every two weeks. This will create well-branched plants full of blooms. Do not allow mums to bloom early in the summer, usually a reaction to severe heat or dry soil. Mums should be irrigated during dry spring – summer periods. Mulching helps to conserve soil moisture and protect plant crowns overwinter.

Caveat: some greenhouse growers are also marketing older mums as “heirloom” varieties, popular 30-40 years ago. Some of these varieties are still excellent garden performers. However, some tend to be disease prone or weakly branched.

Fall Is Great Time To Renovate Your Lawn

Posted by Hugh on September 5th, 2013

Core aerator for lawn renovation

Is your lawn nothing but bare spots, thatch, and weeds? Late summer and fall is an ideal period to reduce thatch build-up and repair dead lawn areas. Thatch is composed of old grass clippings, e.g. leaf and stem debris not decomposed. By aerating the soil and removing thatch, you will improve soil water absorption and fertilizer uptake by the grass roots.

Equipment rental outlets in your area have “core aerators” and “spikers” to loosen the compacted soil and remove the unwanted thatch from the surface. Make two passes, criss-crossing the lawn area north to south and east to west. Next, rake up all loosened thatch and compost this organic debris to improve your garden soil in the future.

Since you have shallow-tilled the soil, use this opportunity to disperse grass seed. Most equipment companies rent a slit seeder for this task. Professional lawn companies also provide this service. The equipment tines slice through the soil and drop the grass seed in place. Fertilize and irrigate after seeding as needed.

The invasion of most annual weed grasses, such as crabgrass, goose grass, and foxtail, is over for the year. The cool autumn weather will destroy weedy roots and shoots. Unfortunately, all the seeds that the weed grasses dispersed will germinate next spring and summer. Thickening and improving the health of the home lawn this fall should choked out most weed seeds next spring.

Tending to problem broadleaf weeds such as dandelions, clover, ground ivy, thistles, plantains, and wild garlic is your final step. Broadleaf weeds can be managed by using contact herbicides containing triclopyr, dicamba, and MCPA. Products that contain all three ingredients are recommended.
Caveat: do not use any herbicides until the new grass seeding (or over-seeding) have been mowed at least twice.

Seeds One Year…Weeds For Eight Years

Posted by Hugh on September 1st, 2013

Beautiful Bed of Medallion Flower (Melampodium) at Dallas Arboretum

Most weed invasions happen when you let the weeds get past you. If you don’t let them flower, they won’t reproduce (seed-in). Frequent mowing or a sharp machete may delay their ability to flower and seed. This is only a temporary solution. Some weeds flower and seed below the mower’s cut. Examples are common lawn weeds such as dandilion, field morning glory (bindweed), goosegrass, crabgrass, and white clover.

Favorite garden annuals and perennials may also become weedy nuisances. Some seed-in by the hundreds, overwinter, and germinate all over next spring’s garden. Perennials like summer phlox (Phlox maculata), black-eyed Susan (Rudbeckia), spiderwort (Tradescantia), tovara (Persicaria) and goldenrod (Solidago) can become serious invaders.

Annuals such as marigolds, celosia, verbena, and violas frequently come back often 2-3 years after they were excluded from the flower bed. Three of the worst are morning glory (Ipomoea tricolor), medallion flower (Melampodium) and Jewels of Opar (Talinum) which many Tennessee, Virginia, and North Carolina commercial landscapers have banned them from future clients’ plantings.

A third class are the winter annual weeds such as annual bluegrass, henbit, and common chickweed. Their seeds are dispersed by mid- to late-spring and germinate in cool fall-winter soils when plenty of moisture is available.

Chemical weed preventatives are available if you anticipate a weedy future. One of the active ingredients is Preen® (also called Treflan®). Apply before the targeted weed seeds germinate…early fall (October) or late winter (March).

Talinum (Jewels of Opar) at Dallas Arboretum

Daylilies Not Blooming?

Posted by Hugh on August 29th, 2013

'Going Bananas' daylily

Gardeners become disappointed when their daylilies (Hemerocallis spp.) are not bloom. There may be reasons for this including: old clumps in need of dividing, inadequate nutrition, too much nitrogen fertilizer, too much shade, and pest and disease issues.

Daylilies may be shaded or crowded out by overgrown trees, shrubs, ground covers, or weeds. Heavy amounts of grassy weeds, including nutsedges may strangle clumps. Overcrowded daylilies become nutrient starved which reduces their growth and flowering.

As a rule, existing daylily clumps should be dug up and divided every 5-6 years. Early fall is the best time to lift and divide daylilies. They may also be divided in late winter, once outside temperatures have moderated. In most U.S. regions, daylilies should not be divided after mid-October as transplants may heave out of the freezing/thawing ground over the winter. Mulching newly transplanted beds is beneficial to thwart heaving and for winter protection.

Prepare a new planting area, adding lots of well-rotted compost to the soil. The site should receive three-quarter to full day direct sunlight. Each division should include 2 to 3 fans and spaced 18 to 24 inches apart. Cut foliage back to 6 to 8 inches.

Choose divisions with lots of thick white roots. Newly-divided daylilies may bloom sparsely their first summer. This is normal. When dividing plants, discard poor clumps, particularly those with dead or wilted foliage. Dispose with the household trash and do not place into the garden compost pile.

It’s not necessary to fertilize new or reworked daylily beds in the fall. Feed in early spring with a slow release fertilizer such as Osmocote 14-14-14, Nutricote 13-13-13, or equivalent products.

Labor Day Holiday Begins Home Lawn Recovery

Posted by Hugh on August 26th, 2013

Beautiful Lawn at Biltmore Estate, Asheville, NC

Hopefully, summer’s extreme heat, drought, and in some areas flooding, are about over. Late summer and fall are opportune times to start a new or renovate your home lawn. Rainfall is usually plentiful and cooler day-night temperatures should spur a rapid grass recovery.

Your current lawn may be mostly bare ground with lots of weeds. Purchase new grass seed at garden centers or hardware stores. If your present lawn is primarily a warm season grass (bermuda, zoysia, centipede, or St. Augustine grass), purchase ryegrass for fall seeding and hold off on major lawn renovation until next spring or summer. If the lawn is a cool season grass, select either bluegrass, tall fescue, or perennial ryegrass. If you’re not certain, dig up a patch and bring to the local county Extension office for identification.

For small patches, loosen the soil surface with a garden rake and scratch grass seed into the top quarter inch of soil. Seeding rate is on the package. You may lightly sprinkle straw (not hay) over the seeded areas to hide seeds from hungry birds and to conserve surface moisture.

During initial inspection, kill all weeds with a herbicide containing glyphosate (such as Roundup™) and wait 7-10 days for the chemical to do its job. For major repair jobs, use a rototiller to renovate large dead areas. You’re now ready to till the top 6 inches of soil, rake level, disperse seeds, lightly rake into the soil, and cover with straw. You may also choose to lay sod for an instant repair. Installing sod is like laying room carpet.

Your final task is to fertilize the entire lawn with a high nitrogen-based fertilizer that also contains lesser amounts of phosphorus (P) and potassium (K). The fertilizer will not injure the newly seeded or sod areas. Fertilizer plus natural rainfall (or irrigation) makes for a rapid recovery.