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Overwintering Clivia

After a summer outside, my clivia has returned indoors. Last year it had only one puny flower. What treatment should I give it over winter to bring it into bloom?

A. Clivia miniata, sometimes known as Kaffir lily, a South African native, is a member of the amaryllis family. When growing clivia, it is important to observe seasonal changes. During short winter days, stop fertilizing entirely until spring, and stop watering also.

“Treat your plant like a cactus,” says Steve Butcher, tropical plant specialist at Sid’s Garden Center in Palos Hills. “You can keep it completely dry for a couple of weeks up to the point of shriveling before watering. Keep your plant in a cool place; 55 to 65 degrees is ideal, but that’s hard to achieve in many homes. It does not need a brightly lit location.”

When the days lengthen, move the plant into a brighter location and increase watering. There are no hard-and-fast rules on watering. The frequency depends on the pot size and the root mass. Use a water-soluble, high-phosphorus fertilizer every second or third watering. After you see buds, reduce fertilizer to once per month. Root bound plants flower better.

Following this regime last winter, Editor Carolyn Ulrich reported five bloom stalks on one of her plants in February. Other plants bloomed in March but one didn’t bloom until June. Clivia are considered a winter-flowering houseplant, but bloom time will vary. Be patient.


Planting Tulips

Is there a best time to plant tulips? I see them at the garden centers in late summer but I am afraid that it is too early to plant them. If I wait too long, I might forget all about them.

Fall bulb planting should wait until soil temperatures drop to 55 degrees or cooler. This usually occurs when nighttime temperatures drop to 50 degrees or lower for two weeks or more. While waiting to plant, store the tulips in a cool, dark place away from direct sunlight—but don’t forget them. After planting, water the bulbs well, advises the Netherlands Flower Bulb Information Center.

If you plant grape hyacinth bulbs amidst your tulips, they will come up early in the fall and serve to mark the position of your tulips.


Slugs

I am sick of slugs. Perhaps if I knew their life cycle I could get rid of them. Where do they go over winter? Where do they come from? What is the best way to get rid of them?

Slugs are gastropods belonging to the mollusk class. They have lungs and can breathe air and live one year. At nightime, to conserve moisture, they feed by biting tissue with a rasping mouth underneath their body. They move by sliding over slime secreted by a large muscular foot and constantly lose water from this slime production and evaporation.

To make matters worse, they are hermaphrodites having both male and female organs and can deposit egg-like clusters of 1/8 inch pearls in soil where they overwinter. Their growth is activated by rising soil humidity and temperature in the spring, according to Ed Valauskas, Manager of Library and Plant Information Services at the Chicago Botanic Garden.

Even if your soil is relatively slug free, they can come in from a neighbor’s yard or live in the soil of container-grown plants. If you garden in very sandy, fast draining soil, you will probably not have many of these pests, but in heavy clay soil, slugs find constant moisture that suits their life style.

Slugs feed on plants with moisture in them, especially hosta, ligularia, dahlia and begonia leaves, lettuce, strawberries and tomatoes. They hide by day and feed at night or on gray, damp days. Go outside with a flashlight after 10 p.m. and look for them under boards, rocks or pots and destroy them.

Laurie Skrzenta of Laurie’s Landscape, a Downers Grove hosta grower, keeps the hosta area dry and doesn’t water them because slugs do not live in dry locations. She depends on rainfall and maintains that hostas can exist without supplemental water. Laurie also suggested using coarse sand as a mulch. Another possibility is to sprinkle sand in the center of your dormant hostas since this is where the slugs lay their eggs.

There are many home remedies to get rid of slugs including beer, ammonia water, ice water, and yeast water. Gardener Anna Hevrdejs, Woodridge, suggests sprinkling corn meal around slug areas. Slugs like to eat it, then die. Replace it after a rain. She also claims that sweet woodruff planted around hostas restrains the slug population.

Chemical metaldehyde or methiocarb pellets are useful but they can be attractive to dogs and children. They are very toxic. Much safer is a copper strip laid around the areas to be protected, although this is not practical in an ornamental garden.


Azalea

We moved into a house with a lovely azalea that didn’t bloom. We thought it might have been over-pruned. Last fall we did not prune it and now it still hasn’t bloomed. I was hoping to transplant it this year, but it looks rather sickly. Shall we prune it again and give it another year? Can I still transplant it?

Stop pruning your plant since you may have over-pruned it. Evergreen azaleas only need tip pruning in July after their flowers have faded.

Concentrate now on rebuilding the azalea into a healthy plant. Do not transplant a sickly one. Feed your plant regularly with an liquid acidic fertilizer. Keep your plant weeded and its roots moist by using mulch because azaleas are surface rooters. Make sure your plant is situated in soil with good drainage and in a part sun/part shade location.

Try this regime over summer and evaluate your plant next spring, advises Charlene Wooten, manager, Cedar Hill Nursery, Lake Zurich.


Dwarf Junipers

Why do I have brown areas near the tips of my dwarf Japanese junipers? This has been occurring the last few years. They are supposed to be drought resistant”

“It’s hard to diagnose without seeing the plants or their location,” says Matt Warrick, sales associate in tree and shrubs at Gethsemane Garden Center, Chicago. “Your plants may be in a situation that’s too dry. With the type of drought we had this past summer, even if a plant is drought-tolerant, it would have needed supplemental watering.”

Other factors that affect junipers are poor drainage, insufficient light, fungal disease, and insufficient acidity in the soil. Any of these conditions could cause needle browning.


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.


Raising Lawn Level

I want to raise the level of my lawn as much as 2 feet in places. I now have a large quantity of somewhat composted wood chips and I am wondering if I can use them as fill to raise the ground level and provide a good soil in which to sow a lawn.

“It is not a good idea to use only wood chips to raise the grade of an area,” says Greg Stack, University of Illinois extension educator, horticulture. While wood chips may raise the grade for a while, over time they will decompose and eventually the site will sink. Even using them as fill and putting soil over them is not a good idea.

“I would not use straight compost by itself to raise the lawn level, but mix it with soil,” adds Stack.


I've got green worms!

What is the green worm that eats my roses and columbine every year?

It is hard to diagnose your problem without seeing the caterpillar. There are several green worms that bother roses, and one can be controlled with Bt (Bacillus thuringiensis) but rose slug, for example, cannot. Proper identification is necessary before applying any control method. Do not use an insecticide for anything that"s not on on the product label. Do not use any insecticide as a preventive measure. It doesn"t work and ends up being harmful to the environment and a waste of your money.

Green worm on your columbine could be an inch worm or canker worm. If the caterpillar loops up in the center or arches as it moves along, it could be a looper or cabbage worm. Leaf miners, which are usually white or pink, tunnel in the leaves. “To eliminate insects, use insecticidal soap,” said Nancy Clifton, Chicago Botanic Garden Plant Information Specialist.

For an exact diagnosis, consult your local University of Illinois Extension service or collect a specimen and bring it to the Plant Information Service at the Chicago Botanic Garden or the Morton Arboretum.


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.


Low Light House Plants

We have a skylight in the bathroom over our Jacuzzi tub with an area around the tub that is quite large. What plants can we grow there, and what care do they need? Can we grow orchids?

Use plants that grow in low light such as pothos, philodendron, peace lily (Spathiphyllum), Chinese evergreen (Aglaonema), any type of dracaena, and include lady palm (Rhapis) for height. It would be possible to grow moth orchids (Phalaenopsis).

“While the bathroom will give you good humidity, your plants must be watered thoroughly. The peace lily needs to be kept evenly moist. Feed monthly with an all-purpose houseplant fertilizer,” advises Elizabeth Hoffman, manager, West End Florist, Evanston.


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