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What plants do you predict will be best sellers this year? Why?

What plants do you predict will be best sellers this year? Why?

Bryon Angerman, nursery manager, Alsip Home & Garden, St. John, Ind. and Frankfort, Ill.

I believe these two compact hydrangeas will be hot plants this year. First is Invincibelle Wee White® hydrangea, a compact and reblooming white variety of ‘Annabelle’ hydrangea. Its dwarf habit of 18-24 inches and versatile adaptability to full-sun to part-shade planting locations will yield three to four months of continuous flowers on sturdy stems. It’s sure to become a staple in every landscape. Also look for Mini Mauvette hydrangea for similar habits with pinkish purple flowers.

Molly Hornbaker Blogg, nursery manager, Hornbaker Gardens, Princeton.

Hydrangea Little Quick Fire will be a best seller this year. It blooms early with pure white flowers turning to pink, then rose. Its more
compact size, at 4-5 feet and fits into most urban gardens better than most other panicle hydrangeas. Hosta ‘Autumn Frost’ is an attention grabbing plant with powder blue leaves and showy yellow margins. Last year’s Perennial of the Year, Asclepias tuberosa, should continue to be a big seller because of its gorgeous orange flowers and because it is a host for monarch caterpillars.

Jennifer Brennan,horticulture information specialist, manager of education, Chalet, Wilmette.

Being at a retail garden center and nursery, I get to hear customers’ requests and questions about plants for their gardens. Being on the board of the Perennial Plant Association for 6 years, I get to hear hybridizers and growers claims about the “BEST” plants. It is wonderful when the claims of the hybridizers and growers match the requests of the gardeners and designers. The other fact that is worth stating is that the plants are trialed much better than in the past, so there is proof from many areas of the country that the recommended plants will perform and survive.

The first plant that I expect to be a good seller is one that has been selected by the members of the Perennial Plant Association as the Perennial Plant of the Year for 2018. It is Allium ‘Millenium’. Allium ‘Millenium’ is one of the very best ornamental onions. Unlike spring-blooming Allium bulbs, this hybrid Allium blooms in mid to late summer with large large 2 inch rose-purple, globe-shaped flowers over shiny deep green strappy, grassy foliage. Mature plants have dozens of globes covering this perennial plant. Allium ‘Millenium’ attracts butterflies and bees love it as well, but deer and rabbits stay away. This Allium is good for winter hardiness Zones 5-9; prefers full sun to part shade and is 10-12 inches tall.

The
second plant is a flowering perennial Echinacea. It is Echinacea KISMET™ Raspberry and it is different due to sheer flower number and a fabulous habit. It blooms first year, early in the season, with large flowers and continues until a hard frost. It is a great plant! I saw it in trials in the Chicago area and in Colorado. It attracts butterflies and hummingbirds. It is a wonderful cut flower with a great fragrance. It is deer resistant. It is hardy from Zone 4 to zone 10. It forms an upright mound that is 16 inches tall by 24 inches wide, up to 18 inches in flower. It is a beautiful hot pink color that blooms June, July, August, September and October. And, it likes average well drained soil in full sun.

The third plant is a hybrid of a native grass. Native plants are one of the strongest trends in gardening these days. The natural beauty of native Blue Grama Grass is raised to a higher level in Bouteloua gracilis ‘Blonde Ambition’. Its allure includes an abundance of horizontal seed heads, which resemble elegant, petite flags. They emerge chartreuse and transform to blonde. These exquisite blooms hover above thin, blue-green, two-foot stems. ‘Blonde Ambition’ was named a 2011 Plant Select® Winner for its resistance to pests, exceptional performance in low water conditions, retail appeal, and long-lasting attractiveness in gardens and containers. It pops right back up after snowfall. Bouteloua gracilis‘ Blonde Ambition’ was discovered and introduced by David Salman of High Country Gardens. It is easily grown in average, dry to medium, well-drained soils in full sun. It tolerates a wide range of soils, except poorly-drained, wet ones. It is hardy from Zone 3 to Zone 10. It is a tufted, warm season, Missouri native grass noted for its distinctive arrangement of mosquito larvae-like seed spikes which hang from only one side of its flowering stems. It is native to prairies, plains, open rocky woodlands and along railroad tracks. It has narrow, bluish-gray leaf blades (to 1/4 inch wide) that typically form a dense clump growing 12-15 inches tall. Foliage turns golden brown in autumn, sometimes also developing interesting hues of orange and red. Inflorescences of blond colored flowers appear on arching stems above the foliage in early to mid-summer, typically bringing the total height of the clump to 20 inches tall.

All three of these should be at the top of the selling lists for the 2018.


Rose Rosette Disease (RRD)

What is rose rosette disease? I lost two antique roses and removed a hedge of multiflora roses that were supposed to be undesirable. How bad is it?

Rose rosette disease is a plant killer of unknown origin and no known cure. It is known to plant pathologists, but unknown to most rose gardeners in this area.

The disease is believed to be caused by a virus or virus-like pathogen that has been spreading through much of the wild rose population in the Midwest, probably transmitted by a mite introduced to the U. S. to eradicate multiflora roses. It is lethal to the wild multiflora rose and potentially lethal to many rose species and cultivars.

Symptoms of rose rosette disease are highly variable, depending on the species or cultivar. Some of the more recognizable symptoms include rapid elongation of new shoots forming witches brooms, or clustering of small branches with distorted leaves of conspicuous red pigmentation and distorted flowers.

David Robson, Springfield, extension educator, horticulture with the University of Illinois, reports that it is all over our area. Mike Geimer, owner of Geimer Greenhouse, Long Grove, reports coming across RRD in a Long Grove garden. One plant in a bed of Flower Carpet roses caught his eye because of its uncharacteristic red clumping stems. He looked up the symptoms on the internet, identified it as RRD and advised immediate removal of the plant. Also important, warns Geimer: “Always sterilize pruning shears.”

Kathy Hallgren, Sycamore, is worried about the future of old roses. Two summers ago she noticed some peculiarly rampant irregular, hyper-thorny pink growth with irregular leaves on an antique Alba rose.

After researching the symptoms, Hallgren determined the irregularities were from RRD. “I dug out the plant and burned it. Once I learned that multiflora roses could be the culprit, I removed them even though they were healthy. This summer I saw it on one of my ‘William Baffin’ roses so cut it down and burned it. This disease means business,” says Hallgren.

No effective control is available for existing rose rosette disease. All cultivated roses are potentially susceptible. Be on the lookout for it. Early detection is the key to effective cultural control. If the disease is recognized early and the rose is removed, it is possible to save other roses in the garden and hopefully curb the spread of RRD.


Siberian Iris

My Siberian iris ‘Gracilis’ plants have only one bloom per clump. I have five 3 to 5 year-old clumps that are 8 to 10 inches wide. They do not appear to be crowded. All are planted in a moist area. Why is there only one bloom per clump?

“Iris bloom is directly proportional to the amount of sun received,” proclaimed Chuck Simon, Hinsdale, past president of the Northern Illinois Iris Society, who grows 10,000 rhizomes of 1,000 to 1,500 iris varieties. Iris need 4 to 5 hours of sun, but full sun is best. Another cause of bloom failure could be iris borers, which eat mature fans and cause only minor increases in plant growth. Spray with Cygon 2E in spring when eggs of borers hatch in order to break their life cycle. When transplanting iris, make sure the roots remain moist. Grow them in moist but not wet soil. In the first year after planting, water them religiously. Once past that point, they are very hardy. Simon, a master iris judge, referred to the American Iris Society checklist for any special cultural conditions affecting bloom and discovered that this variety is very old. Iris siberica ‘Gracilis’ was introduced in 1927.


Purple Coneflower

I have read that purple coneflowers (Echinacea) are a good source of food for birds in the winter. Will they be okay if not trimmed back until spring? If so, how early should they be trimmed?

If your coneflowers remain standing over winter, the seed heads will be available as bird food and will also be an attractive presence in the winter garden. They should be cut back in early spring before April. If you prefer, you can cut the plant back after frost and throw the seed heads on the ground.


Plumeria

I brought a frangipani (Plumeria) back from Hawaii last April when it was just a leafless branch. It sprouted leaves and grew over summer. Now it is losing its leaves. How can I keep it growing over winter? Will it bloom?

During winter, plumerias defoliate naturally. Keep your plant somewhat dry.

” We keep it in the cactus section over winter because it really likes to dry out. It doesn’t need a lot of misting. A southwest window with bright light is the best exposure for it.” says Lourdes Espinosa, greenhouse associate, Sid’s Nursery and Greenhouse in Palos Heights.

In spring, depending on the weather, and as the days lengthen, resume watering and fertilize with a high-phosphorus liquid fertilizer every two weeks. When the night temperatures remain reliably above 50 degrees, the plumeria can be grown outside. Acclimate the plant slowly to the outdoor light by keeping it in a shady place for a week. It flowers from summer to autumn.

Plumerias can grow into a 3-foot shrub with good care. Wear gloves when pruning since the sap is toxic and irritating to the skin.


Italian Cypress

Is it possible to plant and grow Italian cypress in the Chicago area? Are our winters too severe for it? If they are, is there an alternative conifer that will provide a similar look?

Italian cypress (Cupressus sempervirens) has dark green foliage and horizontal branches and grows into a dense column 60 feet high in Italy. It is not hardy here.

Paul Jeffers, tree and shrub salesperson, Gethsemane Garden Center, Chicago, suggests substituting a dense, columnar arborvitae, (Thuja occidentalis ‘Fastigiata’). It grows to 25 feet tall and 5 feet wide, but can be kept lower by pruning. The very narrow arborvitae ‘DeGroots Spire’ is another choice. The false cypress Chamaecyparis nootkatensis ‘Green Arrow’, often mistaken for arborvitae, is a tight upright growing plant.


Overwintering Marginal Plants

I keep seeing photos of interesting plants I’d like to grow, but they’re labeled zone 6 and I’m in zone 5. What can I do to successfully overwinter these marginal plants? I’d like to try them, but I don’t want to waste my money.

“Pushing a plant past the limits of its hardiness is not for the average gardener,” says Marie Dvorak of The Planter’s Palette in Winfield, “but plants can sometimes be successfully overwintered by siting them in a special microclimate such as a sheltered southern exposure.” Another tip comes from horticulturist Ann Hancock at Michigan State University, where they are trialing perennials that the English firm Blooms of Bressingham is introducing in the U.S. Hancock explains that the best way to keep perennials that are tender in Zone 5 or that are rated for Zone 6 is to grow them in raised beds with good drainage because poorly drained wet soils will cause the roots to rot. In addition, it is important to check perennial beds for plants that have heaved out of the soil through repeated freezing and thawing. Replace them in the soil and protect with mulch.

One example of a marginally hardy plant that will be getting attention this year is ‘Flamenco’, a new cultivar of Tritoma (Kniphofia, red-hot poker) that has just been named an All-America Selections Winner for 1999. Tritomas should have their foliage tied upright so water does not remain in the crown, said Hancock.


Peony Blight

Last summer my neighbor told me the black spots on my peony were a blight, although my peonies bloomed nicely. What can I do about this?

Your peonies probably have a fungal disease, a common problem. The causes are wet summers with cool damp nights, too much shade, poorly drained soil, or a lack of air circulation. While your neighbor diagnosed your problem as peony blight, which is caused by an air-borne botrytis fungus, the black spots indicate the more common phytophthora blight, according to Walter Schmidtke, nursery manager at Pesche’s Garden Center in DesPlaines.

Early in the spring, young emerging shoots may suddenly wilt and fall over, turn black and show masses of gray-brown botrytis spores. If nothing is done, these spores are carried to developing buds, which turn black.

Black spots on foliage, leaves turning red in summer, and black stripes on the stalk indicate phytophthora. “Plants with these conditions won’t have as much zest” said Schmidtke.

The best protection against recurrence of either blight is good sanitation. In fall, it is important to cut down and throw away all peony foliage, cutting stalks just below the surface of the ground.

If this doesn"t work and you resort to chemicals, the treatment is the same for both diseases. As soon as the shoots emerge in spring, begin spraying with Mancozeb, a copper sulphate solution, and repeat every 7-10 days until buds form, according to University of Illinois Extension. Spray the whole soil area for overwintering spores. In early summer you can spray plants with Daconil, a general purpose fungicide. Cut away any diseased foliage at once.


Variegated Sedum

I have a large variegated sedum with pink flowers that I have had for years. I noticed that it has started to send up some all-green shoots. Why is it doing this and how can I keep my plant variegated?

All variegated plants contain a combination of green cells with chlorophyll and white tissue with no chlorophyll, which produces the green and white effect. Variegated plants are genetically unstable, so sometimes the tissues revert to all-green cells and send up solid green shoots from the base of the plant. Because these shoots contain more chlorophyll than the variegated tissue, they are more vigorous. Thus they can quickly overrun a plant, according to Hortech, a developer and grower of sedums.

Cut the green shoots off at the base of the plant as soon as you see them. It is possible you have induced vigorous growth by giving the plant too much high-nitrogen fertilizer, so it would be wise not to fertilize. It sometimes helps to divide your plant and then choose the most variegated stems for a new plant. Since your sedum, a cultivar of Sedum spectabile, is such a rapid grower, it will quickly become a new clump after division. Newer named cultivars are more genetically stable and do not have this problem.


Rose of Sharon - Botrytis Blight

I have two 3-year-old rose of Sharon plants, about 20 feet apart. One blooms every year. The other plant forms about 100 buds and looks healthy, but it has not bloomed in the last two years. The buds are solidly closed and look as if they are rotting from the inside out. There does not seem to be any sign of insects on the plant. What is this problem?

From the description it sounds like your plant is infected with botrytis blight, a fungus disease that attacks buds before they open, according to Jim Schuster, extension educator, horticulture, University of Illinois. Your plant needs to be treated with a fungicide early in the season. Remove all diseased portions of the plant and any residue on the ground, as the fungus lives over winter in discarded material.


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