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Amaryllis Bulbs

I plan on saving my amaryllis bulbs that I kept outside over summer, but I noticed red streaks on the inner side of the leaves. What caused that? Will I be able to save my bulbs?

There are several possible causes of red streaks in amaryllis hybrids (Hippeastrum), explains Bill Welter, owner of Victor Hlavacek Florist, Winnetk. If the streaks occur on the foliage only, excess moisture and not enough air around the bulb could have caused the streaks. Amaryllis is also susceptible to leaf scorch, which can cause red streaks on the foliage and on the bulb. This was common on older varieties.

You can save the bulb for next season by letting the leaves die down, then trimming off the foliage, and dipping the bulb in a fungicide solution. Another possible reason for leaf scorch is tobacco mosaic disease, transmitted by insects.


Trumpet Vine

Will a trumpet vine growing on a tree harm it?

Trumpet vine (Campsis radicans) is a vigorous vine which can climb to the top of a tree in one season and spreads by suckering roots. It blooms in full sun in clusters of 3-inch-long orange tubes with flaring scarlet lobes.

The vine will not harm an established tree but a young tree could be stressed.

“There may be root competition between the vine and the tree for moisture, especially if your tree needs a lot of water. However, trumpet vines can grow with less moisture. When customers claim their vine does not bloom, it is because they are watering and pampering it too much,” says Lori Harms, greenhouse manager, Countryside Nursery and Garden Center, Crystal Lake.


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.


Hydrangeas

When is the best time to cut back hydrangeas? How far do I cut them back?

Pruning hydrangeas depends on the species. Oakleaf hydrangea (H. quercifolia) and Peegee hydrangea (H. paniculata), with its well-known cultivars ‘Limelight’ ‘Little Lamb’ and ‘Tardiva’, are woody shrubs that bloom on old wood. Trim them within two to three weeks after flowering. The following year’s primary flower buds form near the top of the stems in late summer. If you wait too long to prune, you will be cutting off flowers on the old stems.

The new bigleaf hydrangea (H. macrophylla) ‘Endless Summer’ is an herbaceous plant that dies to the ground over winter and starts into new growth in spring. It can be cut at any time since it flowers on both old and new wood.

Hydrangea ‘Annabelle’ (H. arborescens) can be trimmed at any time. “It dies back totally to the ground each year so you can keep it trimmed to the size you want,” says Jean Bragdon, garden center manager at Lurvey’s Garden Center, Des Plaines.


Voles

How can I get rid of voles? I think they are doing a lot of damage to my bulbs.

Voles are mice-like rodents that gnaw on roots and bulbs. They are hard to control.

There are repellents on the market that you can try—Deer Off, Moletox, and a new product named Shot Gun Repel. The latter repellent was designed specifically to protect bulbs from chipmunks, moles, voles and mice. Treat the bulbs before storing or planting. Remove old skin and soil, and then spray thoroughly until wet. Allow the bulbs to dry before storing or planting.


African Violets

I have twelve beautiful blooming violet plants on my office desk, placed 12 inches from a light source that’s kept burning day and night. I water them from the bottom and let the water remain in the saucer.

No matter what I spray, I continue to have gnats and other insects in my soil. I also occasionally start to get yellow spots on the tips of the leaves and then the spots start going down the leaves. What’s going on here?

A number of factors could be causing your problems.

“Yellow tips indicate your plant is showing stress either from lack of humidity or watering too much; it’s hard to pinpoint,” says Sandy Fuller, Palatine, past president of Barrington Bloomers, who grows 100 African violets under lights in her basement.

Peat-based soil needs to dry out for fungus gnats to disappear. Use a magnifying glass and try to identify them. Gnats eat only decaying plant material and do not damage the plants. If you have mealy bugs, their cottony waxy sac is easy to identify.

Office tap water may be too cold. Let it sit for half a day before using it. If the water is too cold, the plant could rot. Some violets are more sensitive than others to temperature changes.

Repot your plants in African violet soil and use a 20-20-20 fertilizer.


Hellebores

From what I have read, hellebores are supposed to spread. I have a few I planted four years ago, and they seem to be the same as when I planted them. They are planted in a bed of vinca. Should I remove more vinca that surrounds them? I do fertilize them and protect them with a winter mulch. What else should I be doing to have more plants?

Hellebores increase slowly into clumps so have patience, counsels Chris Darbo, wholesale manager of The Natural Garden, St. Charles, and an enthusiastic hellebore grower. “I have Helleborus foetidus, which has finely cut leaves and blooms in January, and H. orientalis, the Lenten rose. Both have increased in twelve years to four times the size of the original plants, but they haven"t self sown. They are planted in a bed of sweet woodruff in a partly shady location.”

“I also have a clump of H. orientalis that was transplanted into my back yard five years ago, and it seeds all over the place. It is planted in shade with no ground cover. My theory is if the seeds can"t reach the ground, they can"t grow!” It takes three years before seedlings bloom.

According to Darbo, hellebores do not need fertilizer. She never rakes leaves from garden beds but instead lets fallen leaves act as a winter mulch. Leaf decomposition over the years has helped her soil to become more loamy.

H. niger, the Christmas rose, does not self seed as readily as H. orientalis and H. foetidus.

Note: A new strain of H.orientalis has recently reached the market. Known as the Royal Heritage strain, it includes colors and patterns never seen before in the species. Fifteen years in the making, Royal Heritage hellebores were developed by John Elsley, Director of Horticulture at Song Sparrow Farm in Avalon, Wisconsin.


Tomatoes

After my father’s tomatoes ripen on the vine, he finds when he cuts into them that there is a hard white core that extends through the fruit.

“This is a common problem,” says Dan Woldhuis, owner, Woldhuis Farms, Grant Park. “Customers bring their tomatoes to me with hard cores.”

Sometimes this is the result of weather that’s too hot and then suddenly cold.

But more likely it is the variety. Change to a soft-skin, less firm tomato such as ‘Celebrity’ to overcome the white core problem. I’ve grown this for many years and sold it at the farmers’ market, but it is too soft for the commercial market and is best for home growers.


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.


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.


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