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Strawberries

I have two strawberry plants in a hanging basket in my yard. I have not had any fruit from them although the vines hang down. I give them plant food once a month and water daily. What am I doing wrong?

Fertilizing your plant with a high nitrogen fertilizer causes excessive leaf growth. Clip the runners so the strength goes into flower and fruit production. In winter, make sure the plant roots do not freeze in the hanging basket, according to Joni Cotton, Hawthorn Gardens, Hawthorn Woods.


Pre-Chilled Bulbs

I purchased some pre-chilled hyacinths and tulips for forcing but there were no directions with them. Does this mean I don’t have to chill them in the refrigerator, and will they just bloom in the house any time during the winter? The last batch of bulbs became moldy in the refrigerator.

Using pre-chilled bulbs avoids the 12- to 14- week cold treatment that bulbs need for indoor blooming. However, you need to pot up the bulbs in a loose potting mix. Do not cover the bulbs in plastic wrap or paper bags. It will still take 3 or 4 weeks of cold for roots to appear.

Hyacinths kept cool do not need to be potted. They can sprout roots in a saucer of water with the bulb held in place by stones. Check the water level and make sure it just touches the base of the bulb and add water as needed.

The bulbs can be forced as soon as you see roots, or you can hold them in the cold temperature to space out the bud development. Place rooted bulbs in bright light in a cool room, and watch for buds. Rotate the plant so the flowering stem will be erect. “Your previous bulbs rotted because they were not potted up,” says Lori Harms, greenhouse manager, Countryside Nursery, Crystal Lake.


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.


Cold Frames

With all the emphasis on growing fresh vegetables, I think I should use a cold frame but I am not sure what to do or how to go about it. Any ideas?

Cold frames are simply four walls with a window or plastic sheet on top. They range from simply placing four bales of straw in a square with an old window atop them to more deluxe mini-greenhouses with aluminum frames, plastic panels and automatic vents using solar energy to open and close them automatically.

Before building a cold frame, study garden supply and greenhouse catalogs to determine your needs and how fancy you want your cold frame to be. Do you prefer a permanent installation or an easily disassembled frame?

A basic plan for building a cold frame is taught by Chicago Botanic Garden’s senior horticulturist Heather Sherwood. Create four walls from plywood or bricks. Add a transparent lid (plastic sheeting or an old window) for light to enter. Place the lid on an angle. Place the frame against a building, facing south. Make sure there is good drainage. Open the frame when it gets above 60 degrees. Rabbits don’t usually get into the box but chipmunks may squeeze in.

Cold frames are used for extending the growing season, starting plants early, for storing bonsai or protecting semi-hardy plants over winter. The soil in the frame depends on how you will use it. The frame can be set on existing soil when you are storing plants, or fill it with straw to protect bonsai. Locate it conveniently against the house near a back door for easy access, especially if you envision running out to cut some salad greens when snow is on the ground.

Use a cold frame to get a head start on the gardening season. In early spring, start flats of lettuce, radishes, parsley, pansies and other cool-weather plants in the house, and place them in the cold frame in March, depending on the weather. If you plan on planting directly into the cold frame, fill it with a seed starting soil mix and an inch of compost worked into the top 3 inches of the soil. This will help keep the soil loose and aid moisture retention. The plants will be small in the cold frame and can be grown close together. Also use the cold frame to harden off house-grown seedlings.
Don’t forget to check on your plants regularly because winter sun is strong and plants dry up easily. Use it for a head start on the gardening season.


Cycas

I have a cycas palm and am not sure how much direct sunlight or water it needs. It has light brown marks developing on the leaves. What is causing this, and how do I care for my plant?

Cycas palms or sago palms (Cycas revoluta) are tough house or patio plants. They are neither palms nor ferns but primitive cone-bearing relatives of conifers. A rosette of green feather-like leaves, 2 to 3 feet in height, grows from a central point at the top of a single trunk.

Cycas need bright light and should be kept relatively moist with weekly watering. However, prolonged rainy spells can cause fungal leaf spot disease.

“The shiny brown spots are probably caused by scale,” says Jeff Frohn, sales associate at Geimer Greenhouses, Long Grove. “It can be treated with fish oil, vegetable oil or an all-in-one insecticide spray,” adds Mike Geimer, owner, Geimer Greenhouses.


Orchids

What causes black spots on my orchid leaves?

There are a number of causes for black spots, depending on the type of orchid.

“In some varieties, like Oncidium ‘Cherry Baby’, the small black spots through the leaf are normal,” says Liese Butler, owner, Oak Hill
Gardens, Dundee.

Black spots on the top of the leaf could be sunburn, caused when sunlight scalds a drop of water that has been left on a leaf. Newer growth of Cattleya orchids can normally have a purplish spot. A black mushy spot and a black stem indicate rot.


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.


Houseplants

I have houseplants outside that I will need to bring indoors. What is the lowest temperature at which I can leave them outside?

The rule of thumb is when night temperatures are in the 50s, it is time to bring your houseplants indoors, according to horticulturists at Pesche’s garden center, Des Plaines.

To avoid the shock of suddenly bringing plants into a hot dry environment, place them in a shaded area before the heat comes on in the house. Bring in sensitive tropicals such as hibiscus and anthuriums as soon as summer cools down.

Christmas cactus and cymbidium orchids can tolerate chillier temperatures and stay outdoors longer, but move them indoors before the thermometer drops to freezing, says Greg Stack, University of Illinois Extension Educator, Horticulture. Indoors, a cool 50-degree area such as an unheated sun porch will give them the short day situation they need to set flower buds. Stack keeps his Christmas cactus in a cool unused room where the lights aren’t turned on. His plant sets buds and blooms reliably every year, he reports. Christmas cactus buds will dry up in an overheated, dry room.


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.


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.


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