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Coneflowers

I thought that purple coneflowers were insect proof, but now I see some aphids at the bud and tiny flies. What is wrong?

Purple coneflower (Echinacea purpurea) is a common native perennial that grows best in sandy or well-draining soil and full sun. If you are not giving your plant these growing conditions, certain insects can attack your plants.

Aphids are sometimes visible on buds, and as sucking insects they cause stunted and deformed leaves. Spider mites are tiny insects that often multiply in hot, dry conditions. Spider mites feed on sap and cause yellowish leaves. Thrips are barely visible, tiny insects causing bud malformation.


Fertilizer

What ratio and amounts of fertilizer would you use for a perennial bed and a vegetable garden? For growing annuals in a greenhouse, should the fertilizer be fast or slow-release, organic or inorganic?

Use 3 to 5 pounds of a 10-5-10 or 10-10-10 fertilizer per 1000 square feet in the perennial bed. Add leaves as mulch. In your vegetable bed, nutrients are important. Fertilize more heavily using a 10-10-10 fertilizer at the rate of 5 to 10 pounds per 1000 square feet.

For hanging baskets of annuals in a greenhouse, a slow-release fertilizer is best. Use a 20-10-20 liquid fertilizer following label directions. In general, organic fertilizers have a lower chemical analysis than inorganic ones, so you have to use more, according to David Tyznik, owner of Planter’s Palette, Winfield.

A healthy plant is dependent on its soil. A balanced soil is rich in beneficial microorganisms that improve the soil structure and supply necessary nutrients. Soilless potting mixes have no microorganisms. “Both organic and inorganic fertilizers work well, but those in soilless mixes need more fertilizer,” says Tyznik.


Fresh Figs

I recently moved to Chicago from Houston and I miss fresh picked figs. Is there any way to grow figs in Chicago short of installing a greenhouse? Will sunny windows do? I’m desperate.

Figs (Ficus carica) are handsome plants with smooth gray bark and large lobed leaves which can grow into gnarled trees in warm climates. In Illinois, with winter die-back, they are grown as shrubs. They should be sited where they get some protection from the wind in winter.

You do not need a greenhouse to grow figs, and a sunny window would not be appropriate. Grow a fig cultivar suitable for this climate. While most figs are rated to winter hardiness zone 4, the problem comes because our growing season is too short to ripen fruit, which may take until September or October in a cool summer. Sometimes we have an early frost. If so, pick unripened figs and let them ripen in the house.

Alana Mezo, senior horticulturist for the fruit and vegetable island at the Chicago Botanic Garden, recommends ‘Chicago Hardy’ fig, the variety they grow. They have 10 or 12 plants there growing in a row and, through trial and error, have decided not to protect them over winter because rodents chew roots and stems in wrapped plants and set back their growth. Their figs are multi-stemmed, die back to the ground when unprotected, and get off to a slow start in the spring, delaying fruiting.

However, if you do not have a rodent problem, tie the stems together, wrap burlap around the tied stems, and cover the base with a basketful of leaves. With this protection, your plants will have a head start in spring, and you should have figs ripen a month earlier than unprotected plants, at least by late August.

Another method of winter protection is to root prune in a half semi-circle around the plant, lay it down and cover the plants with leaves over winter.

If you grow a fig in a large container, you can wheel it into an unheated garage and store it over winter. Watch it to see if it needs moisture. Your plant does need a dormant cold period, but not a freeze. This is an “iffy” process according to Mezo.

A fig grower in Highwood claims that rubbing olive oil on the fig hastens ripening, but Mezo has not tried this yet.


Staking Plants

I dislike staking perennials. Is there anything I can do to avoid it?

There are several techniques you can use to limit time spent on this chore, but it is difficult to totally

avoid staking some plants.

First and foremost, the old adage “right plant, right place” means full sun perennials need to be grown in full sun for tight upright growth. If they are too shaded, the plant will stretch or bend toward the sun and grow in a loose habit. Growing plants a little closer together also helps because it enables plants to support each other.

The best remedy to avoid staking is to cut some tall plants down by one-half in June. That will delay flowering in helenium, monarda, platycodon, chrysanthemum and aster, but the plants will remain upright. If you really want to eliminate cutting back, grow dwarf versions of these plants.”
Short, thin branches from forsythia or dogwood (known as “pea staking” in England) can be placed around the perimeter of newly emerging plants to help keep the stems upright. Some garden centers have begun selling bundles of branches for this purpose. In a short time, the shrub cuttings are covered by emerging shoots. This technique works well with fine foliage such as baby’s breath or flax.

There are numerous staking supports from bamboo to iron rebar rods. Wire staking supports are available in full, half and even quarter circles to support single stems. Peony hoops can be left in place over winter and will support not only peonies but boltonia, baptisia, and even errant tomatoes.

Some plants always need to be staked. Giant dahlia tubers need a heavy stake dug into the hole at planting time. That prized, single-stemmed iris, lily, or delphinium can get blasted in a storm, and then it’s too late to save it.

Remember: the time to stake plants is during the cooler days of spring when plants are growing rapidly and not on humid July days. Staking should be done unobtrusively and subtly for plants to retain their natural grace.


Ground Cover Suggestions

I have a dampish area with poor grass and moss that I would like to change to ground cover, but if I have only one plant, won’t it be boring? Can I get rid of the grass in winter or early spring?

If we have a dry winter or spring, you can smother the grass with a heavy layer of newspapers held down by bricks or stones, or use a product that will kill the grass. Use it according to the label directions. Grass roots are very persistent, so you may have to dig out the remaining roots by hand. The moss will disappear as you aerate the soil and rake in organic material.

When your area is properly prepared, you will have a large choice of low-growing groundcovers.

Kim Schroeder, perennial buyer at Wasco Nursery and Garden Center, St. Charles, suggests the following: lily of the valley (Convallaria majalis), sweet woodruff (Galium odoratum), wild ginger (Asarum canadense), or European ginger (A. europaeum), vinca (Vinca minor), Tiarella, Astilbe-the cultivar ‘Perkio’ is shorter than Astilbe chinensis ‘Pumila’ and violas such as bird’s foot viola (Viola pedata) or sweet white viola (V. blanda).

These choices are not aggressive growers like goutweed (Aegopodium), which grows anywhere and is very difficult to eradicate. You can plant free form areas with one type and another alongside it as contrast. Most of these ground covers bloom at slightly different times to give you a spring-into-summer flowering season.


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.


Cucumbers

The foliage on our cucumber plants is starting to wither and turn yellow. They get plenty of water and I feed them regularly. What could be wrong?

“The plants may be getting too much water. They can tolerate fairly dry soil,” says Tim Norris, owner Spring Bluff Nursery, Sugar Grove. There are other possible causes for yellowing foliage as well. The cucumber beetle may have fed on the plants when they were small and transmitted bacterial wilt, which later plugs the vascular tissue. To prevent the beetle from feeding on young plants, use row covers until the plants get larger. A stressed plant is also open to attack by bacterial wilt.


Tree Planting

What is the best time to plant a tree in northern Illinois?

The two best times to plant a tree are April-May or September-October because the weather is cool and there is a good moisture supply, according to Joni Cotten, nursery stock manager, Hawthorn Gardens in Hawthorn Woods. However, planting times can vary, depending on the plant and its method of growth.

Bare-root trees are planted when dormant. They are less expensive, and the planting hole can be back-filled with soil dug from the hole. Trees that have burlap-covered root balls are generally planted in the cooler months, while trees in containers can be planted at any time. Rhododendrons and evergreens are not planted bare root.

“Birches and oaks are dug in nursery fields and planted in the spring. Oaks especially have a long tap root, so they do best when they have the entire season to grow,” says Cotten.


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.


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.


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questions

We are first-time gardeners and have planted Brussels sprouts and green and red cabbage that we are trying to grow organically. There are black egg sacs and small green worms eating the leaves. Is there an organic product we can use on the cabbage?

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.

Late last year most of the leaves on my year-old seven-son tree (Heptacodium) turned brown, starting at the tips. It had some new growth on the tips and buds. I used a tree ring soaker hose every two weeks.

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