May 2015 Culture, Grower News, Plant Health

Perennial Solutions: Heuchera ‘Grape Expectations’ By Paul Pilon

Heuchera is an incredibly popular genus of perennials, which has proven to be one of the most sought after plants in recent history. With what seemed to have been countless introductions over the past decade or so, it’s hard to comprehend how much more this genus has to offer. This month’s feature plant, heuchera ‘Grape Expectations’ proves that further improvements are possible.

‘Grape Expectations’ was bred by Walters Gardens and definitely adds a splash of color to both retail displays and the perennial landscape. It emerges with vibrant grape-purple foliage with black veins in the spring. The leaves are broad, thick and somewhat fuzzy. As the season progresses the foliage holds its color well and develops a silvery overlay, really showing off its dark veins. As cooler weather returns in the autumn, the leaves darken again resembling its spring appearance.

This attention-grabbing plant grows dense upright, but compact clumps reaching 12 inches tall and 24 inches across. Although, the foliage characteristics are the main draw, it does produce creamy white flowers on dark purple 30- to 34-inch stems in midsummer. ‘Grape Expectations’ is a Heuchera villosa hybrid, which means it has increased tolerance for heat and humidity. With good heat tolerance and cold hardiness to USDA Hardiness Zones 4 to 9, this heuchera will perform well across much of the country.

‘Grape Expectations’ has great foliage characteristics, vigor and uniformity making it a great candidate for growers, retail displays, combination containers and the landscape. Additionally, it is deer resistant and attracts butterflies and hummingbirds. Give this one a try and let me know if it meets your expectations.

Propagation

Heuchera ‘Grape Expectations’ is vegetatively propagated by means of tissue culture. Since a plant patent is being sought (PPAF), unlicensed propagation of this cultivar without permission of the applicant is currently prohibited.

Production

Heuchera ‘Grape Expectations’ is well suited for production in small container sizes; typically 1-quart to 1-gallon sized containers. When transplanting, plant them even with the soil line of the liner they were previously produced in. Avoid burying the crown or the plants will grow more slowly and may develop crown rots. Coral bells perform best in a growing mix with both good water holding characteristics and, more importantly, adequate aeration.

Heuchera are light to moderate feeders. Nutrients can be delivered using constant liquid fertilization delivering 75-ppm nitrogen with each irrigation or 150 ppm as needed. Controlled-release fertilizers can be incorporated into the growing mix prior to planting using the equivalent of providing 1.0 to 1.2 pounds of elemental nitrogen per yard of growing mix or applied as a topdressing using the medium recommended rate. When topdressing, avoid piling the fertilizer near the crown of the plant or salt injury may occur. Maintain a soil pH of 5.8 to 6.2 throughout the production cycle.

Grow heuchera using average amounts of irrigation. The occurrence of crown and root rots is greatly increased when they are kept too wet. Drought-like growing conditions often causes damage to the fine root systems, which also increases the occurrence of root rots. For these reasons, avoid really large swings in the wet-dry cycles. It is best to water the plants thoroughly and allow the soil to dry slightly, but not completely, before irrigating them again.

With the compact growing habit of ‘Grape Expectations’, it is usually not necessary to control plant size using plant growth regulators. If your plants need to be toned, spray applications of 30-ppm paclobutrazol (Bonzi, Paczol or Piccolo) or 5-ppm uniconazole (Concise or Sumagic) can be applied. The height of the flower stems can also be reduced using these products; apply one or two applications (seven days apart) when the flower stems are beginning to elongate and are approaching the top of the canopy.

Insects and Diseases

There are only a few problems with insects or diseases that growers are likely to experience when growing coral bells. Occasionally, aphids, mealybugs, slugs, two-spotted spider mites, western flower thrips and whiteflies may be observed feeding on heuchera. The most problematic plant pathogens growers experience are bacterial leaf spots, Botrytis, crown rots, root rots and rust. Other foliar diseases include Alternaria, Cercospora, Colletotrichum and Septoria. The occurrence of plant pathogens can be reduced by managing the environment: provide proper plant spacing and air movement, control the humidity and practice good irrigation.

Generally heuchera can be grown without implementing preventative strategies. Growers can detect the presence of insects and diseases using routine scouting programs and determine if and when control strategies are necessary.

Temperatures and Scheduling

‘Grape Expectations’ is most commonly marketed as a foliage perennial. When flowering is not required, they can easily be grown during the same growing season they are intended to be sold. When transplanting 72-cell liners into trade one gallon containers, it takes eight to ten weeks to finish when they are grown at 65 to 68° F; the production time can be reduced to six to eight weeks when 20 count liners are used. Two-gallon containers can be finished in 12 to 14 weeks when started using 20 count liners and grown at 65 to 68° F. Coral bells can definitely be grown at cooler temperatures, but takes longer to reach a marketable stage than the timings provided above.

If flowering plants are desired, vernalization will need to be provided. This is most commonly done by planting them in the late summer or early fall, bulking them in the final container, overwintering them for at least nine weeks with temperatures below 44° F and then growing them under natural day lengths. They can also be vernalized as large liners and transplanted in the early spring. After heuchera have received a cold treatment, the time to flower is a function of temperature. At 65° F, ‘Grape Expectations’ will bloom in eight to nine weeks.

Availability

Heuchera ‘Grape Expectations’ is exclusively available from Walters Gardens Inc. (www.waltersgardens.com) as 72 or 20 count liners.