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

Enjoy a Mite-free Alberta Spruce This Summer

Posted by Hugh on April 23rd, 2011

Mite free Alberta Spruce

A popular saying among gardeners is “the right plant in the right location”. They must be thinking of Alberta Spruce (Picea glauca ‘Conica’). Within a few years after planting, this popular dwarf conifer becomes devastated by spider mite infestations. The rule is to plant Alberta spruce where it receives good air circulation on all sides.

A common mistake is to plant Alberta spruce close to a building foundation. Here, the needle foliage on the backside of the shrub facing a wall or foundation remains wet. Often, the bottom one-third of the plant is covered with morning dew after a rain or from overhead irrigation.

Initial mite feeding damage frequently starts on the sheltered, warmer side of the shrub. Repeated mite infestations lead to localized stem and needle death which causes Alberta spruce to look unsightly. Similar symptoms are observed in other shrub species, including junipers (Juniperus spp.), hollies (Ilex spp.), and hemlock (Tsuga spp.).

A backup plan is to spray susceptible shrubs with a timely pesticide (miticide). A timely coarse pressure spray of tap water in early spring and again in early fall will wash most eriophyid and spruce spider mites off the foliage.

* Thanks to Dr. Donald Booth, Research Entomologist at the Bartlett Tree Laboratory in Charlotte, NC for his assistance.

Gordlinia- Nothing Like it Before!

Posted by Hugh on April 17th, 2011

(x Gordlinia grandiflora 'Sweet Tea')

‘Sweet Tea’ resulted from crossing franklinia (F. alatamaha) and loblolly bay or gordonia (G. lasianthus). Sweet Tea is still abit finicky like franklinia, but is more resistant to Phytophthora disease (soil pathogen). This new intergeneric cross possesses huge (5 inch diameter), showy flowers that look like big fried eggs. Sweet tea exhibits semi-evergreen foliage with large, single, camellia-like flowers from July through September.

Why name it ‘Sweet Tea’? It’s a member of the tea family (Theaceae). The flowers have a light sweet fragrance. Both parent species originate from the South where sweet tea runs in our veins. Sweet tea must be planted a good well-drained soil with even moisture year-round. It grows best in full sun or a little afternoon shade. Irrigation during summer dry spells is a must. Roots readily from stem cuttings, then takes off growing. Mature height is estimated to be 20-30 feet. Winter hardiness is likely in USDA zones 7 thru 10. The plant is not patented or trademarked.

Photo credit and article info. from Dr. Tom Ranney, NCSU Plant Breeder, Mountain Crops Research and Extension Center, Fletcher, NC.

A Perfect Small Garden Tree– ‘Ace of Hearts’ Redbud

Posted by Hugh on April 11th, 2011

'Ace of Hearts' redbud

'Ace of Hearts' summer foliage

Ace of Hearts redbud (Cercis canadensis ‘Ace of Hearts’) is an arboreal treasure, a compact form of our native redbud. Heavy clusters of light purple pea-like flowers cover twigs and branches from late March into early April, depending on your locality. Ace of Hearts grows 12 by 15 feet in height and spread, roughly one-third smaller than standard seedling redbuds. It makes an ideal fit in small and suburban gardens.

Its small semi-glossy heart-shaped leaves are less than half the size of other redbuds. Leaves are spaced close together, each one overlapping another like shingles on a roof. Its dark green summer foliage turns yellow in autumn before falling. Few, if any, unsightly seed pods are produced.

The overall tree holds its dense dome- shaped canopy over several years. Established (2 years planted) trees are exceptionally heat and drought tolerant. Ace of Hearts is susceptible to very few serious disease and insect problems.

Grow this redbud in any well-drained garden soil in full or partial sun, providing a minimum of 6 hours of sunlight to insure good flowering. This compact grower requires very little annual pruning, which is best performed after flowering.

Wild Onion or Wild Garlic?

Posted by Hugh on April 5th, 2011

Wild Garlic weed patch

Often called “wild onion”, many gardens (including mine) from late winter into spring in eastern Tennessee, western NC and southwest VA are instead plagued by wild garlic (Allium vineale).

Wild garlic forms a rounded blade (stem) while wild onion (A. canadense) has a flattened blade. When freshly cut, the hollow stem of wild garlic is easily visible. Both lawn weeds are edible in a chemical-free lawn and garden. However, chemical herbicides may be your primary option to eliminating both of these noxious weed pests.

Wild garlic forms patches of perennial bulblets which multiply and return each year in greater numbers. Hand pulling is rarely a viable option because the bulblet root system breaks off and sends up a new plant, often within a week. You need to dig and lift beneath the bulbs.

Frequent mowing cuts off flowers to prevent seed head formation. Maintaining a dense stand of lawn grass crowds out wild garlic (and other weeds).

Effective chemical herbicide products include: 2,4-D, Dicamba, Clopyralid, and Triclopyr. Combination herbicides containing two or more of the above products are most effective. Adding a few drops of a spreader/sticker provides better herbicidal action.

This post-emergent treatment also controls white clover, dandelions, ground ivy, thistles, chickweeds, henbits, red sorrel, and wild violets.

No Excuse for Tree Topping

Posted by Hugh on April 1st, 2011

Maple tree "hat rack"

Why do people top trees? Often, it is because “their neighbor(s) did it”. When asked whether they believe their neighbor to be a wise person, the typical response is “NO”.

The Negatives About Tree Topping: 1. A topped tree reduces property values in a community. Topping adds a blight look to a neighborhood or over an entire city; 2. A topped tree is more threatening. Re-growth branches are weak and dangerous to park cars, people, and particularly children playing beneath them; 3. A topped tree costs you more in future expenses; and 4. The tree may not survive topping.

If you feel threatened by a large tree, either have the tree pruned by a certified tree arborist or remove the tree. Select a new replacement tree based on its height at maturity. A properly pruned tree has limbs cutback to their point of attachment to a larger branch or trunk.

What’s wrong with tree topping:

Removal of too much tree top reduces numbers of leaves, starving tree roots
Opening tree center causes sunscald, injuring bark and burning wood which leads to disease
Large pruning cuts don’t heal, causing tree infections
New growths are weak and snap off in wind and ice storms making tree more hazardous
Disfigures the overall look of the tree

‘Misty Blue’ Doll’s Eye Will Catch Your Eye

Posted by Hugh on March 22nd, 2011

White baneberry or doll’s eye (Actaea pachypoda) is a strikingly beautiful native perennial. The cultivar ‘Misty Blue’ was first discovered at Mt. Cuba Center in Greenville, Delaware. The bluish-green foliage is multi-stemmed and finely cut from mid-spring thru the summer months. Grow it in a moist shade garden environment.

Lovely fringed white flowers appear in April. In the fall clusters of white “doll’s eye” berry fruits sit atop brightly red pedicels. Each white berry is marked with a distinct black dot. Fruits persist over 4 – 6 weeks.

Baneberry is a long-lived perennial which thrives in a moist, well-drained, compost rich soil. White baneberry grows 2 – 4 feet tall and is best grouped en masse so that its lovely blue-green summer foliage receives the attention it deserves. Actaea is reliably hardy throughout USDA zones 3 – 8.

Because of its new status, availability of ‘Misty Blue’ baneberry is limited primarily from internet and mail order catalog selling native plants.

Better Choices for Golden Moon Maple

Posted by Hugh on March 15th, 2011

Golden Fullmoon maple

Photo credit: Mr. Brian Upchurch, Highland Creek Nursery, Fletcher, NC

A few months back I asked Mr. Brian Upchurch, owner of Highland Creek Nursery*, his opinion of Golden Fullmoon Japanese maple (Acer shirasawanum ‘Aureum’) in our Southern Appalachian region (USDA zones 6 and 7). He responded: “I have grown it in the past and it doesn’t really thrive in the summer heat of the southeast. Many others have also tried”.

“Golden Fullmoon maple is absolutely gorgeous in Oregon and in parts of Europe. It is rarely seen in Japan, again due to the heat. If you do choose to get an ‘Aureum’, it looks great in the spring, and so-so for the remainder of the growing season.”

As better alternatives Brian suggests “Acer palmatum ‘Summer Gold’, Acer shirasawanum ‘Moonrise’ (PP 16,718), or perhaps even Acer palmatum ‘Orange Dream’ as similar (but not the same) plants. The color won’t be quite as good, but these hold up to the heat better than ‘Aureum’.”

“A new selection of A. shirasawanum called ‘Jordan’ looks promising, but there are no larger plants around. So it hasn’t stood the test of time.”

*Highland Creek is a wholesale only rare plant emporium in Fletcher, NC.

Blueberries

Posted by Hugh on March 12th, 2011

Blueberries (Vaccinium spp.) are healthy for you and exceptionally easy to grow organically (without pesticides). Why?- because blueberries are bothered by very few disease and insect problems. Success in growing blueberries depends upon pre-plant soil preparation. If you’re thinking about growing blueberrues for the first time, then allot this calendar year for soil preparation. Put off planting blueberries until the early fall or next spring. Good bed prep includes:

soil pH of 4.8-5.2 -achieved by an application of elemental sulfur plus acidic organic matter sources such as peat moss and old sawdust
raising and maintaining an organic level of 3% (and higher) incorporating composted leavs and yard clippings, old sawdust and peat moss

Good garden prep takes 12-18 months, so plan ahead. Add another two years for plants to become established and ready for picking. Spacings between plants are 5-6 feet apart for rabbiteye and 4-5 feet for highbush. For large plantings, allow 10-12 feet between rows for mowing, pruning, picking and other maintenance.

Recommended varieties for the Southern Appalachian region (USDA zones 6 and 7):

Highbush: ready for picking from mid-June for 4-6 weeks, cross-pollination not required but recommended. Duke is highly recommended, an early, big berry, excellent quality, and does not tend to overbear. Others are Bluecrop, Echota, Blue Ridge, Berkeley, Jersey.

Rabbiteye: ready in mid-July for 6-8 weeks, cross-pollination with 2-3 varieties is required. Plant Tifblue, Climax, Powder Blue, Centurion, among others.

Act Now for Crabgrass-free Lawn This Summer

Posted by Hugh on March 9th, 2011

What grows there? Hopefully, it’s not crabgrass this summer. Crabgrass (Digitaria spp.) is an annual weed grass that devour lawns, shrub beds and flower gardens. There are lots of effective crabgrass preventatives sold at garden shops, hardware stores, and farm supply centers.

There are numerous trademarked products. It is important to read and understand package instructions. The principal product tradenames (and active ingredients) are:

Barricade® (prodiamine)

Dimension® (dithiopyr)

Echelon® (prodiamine + sulfentrazone)

Pendulum® (pendimethalin)

Ronstar® (oxadiazon)

All products should not be used on newly seeded, sodded or sprigged lawns. In addition several store brands (not listed here) may contain the same or a different active ingredient.

Pre-emergent crabgrass control is your best option. Apply the herbicide in late winter to early spring before the crabgrass seed germinates.

Rather than choosing a calendar date as an application deadline, use forsythia, a common spring flowering shrub, for your timing guideline. If 80 % of forsythia flowers have dropped, expectations for good crabgrass control falls off if a pre-emergent preventative has not been applied.

These products provide 85% effective crabgrass control up to 100 days after application. A second application is required in late spring or early summer for a crabgrass free summer.

One additional tip is to irrigate after applying the herbicide, an equivalent of 1/2 inch of rainfall.

Prune Some Hydrangeas Now

Posted by Hugh on March 3rd, 2011

Hydrangea paniculata 'Limelight' in July

PeeGee or panicled hydrangea (Hydrangea paniculata) and our native Smooth hydrangea (Hydrangea arborescens) are pruned now in late winter thru early spring. Why? – because these hydrangeas bloom on new or current season’s wood.

Over the years these two hydrangea species grow to enormous sizes. When they overwhelm their garden space, severely cut them back to within 6 -12 inches from the ground in late winter or early spring. Next, thin out the number of shoots (canes), leaving several of pencil size thickness. In the spring each cane will grow out new shoots which bloom this summer.

Severe cutting back is called renewal pruning. Timing will vary with the species of hydrangeas planted in your garden. After pruning apply a slow release fertilizer especially formulated for flowering shrubs. Follow the package directions. Apply a good organic mulch to a 2 – 3 inch depth around each hydrangea to conserve soil moisture this summer.

Oakleaf (H. quercifolia) and bigleaf (H. macrophylla) hydrangeas may also be pruned now, but flower numbers in spring and summer may be greatly reduced.