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Climbing Hydrangea

What does it take to make a climbing hydrangea flower? Ours was planted 3 years ago and is growing energetically. It’s in a protected nook near the patio and gets very little direct sunlight, but doesn’t act sun starved. We gave it a shot of slow release fertilizer on planting, and once since. Somewhat inadvertently it gets plenty of water, since the hose spigot is nearby and leaks, but drainage does not seem to be the problem. It now fully occupies an 8-foot trellis but shows no interest in flowering. Is it youth, lack of sun, too much or too little fertilizer, bugs, lack of pruning or what? When do these plants bloom and what conditions do they like?

Climbing hydrangea (Hydrangea anomala subsp. petiolaris) is a choice vine with rich, vigorous, dark green foliage, growing ultimately to 20 feet high and 10 feet wide. The extra moisture it gets is good, and it can bloom in shade. Brent Horvath, president and grower at Intrinsic Gardens, Hebron, has seen it blooming beautifully under a canopy of trees.

After weighing all the cultural factors you described, Horvath has concluded that your vine may be immature and will need a couple more years before it flowers. Climbing hydrangea matures very slowly, especially when it’s sold in 2 gallon containers.


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.


Begonias

I start ‘Dragon Wing’ begonia from seed under grow lights. What other begonias can I use to cross-pollinate with the ‘Dragon Wing’ so I can collect my own seeds?

‘Dragon Wing’ is a unique hybrid type of begonia named to reflect the shape of its leaves. It is created by interspecific crosses of two different begonia species and can lead to interesting new plants, but they are sterile.

It is impossible to say exactly which species will cross and which will not cross. You can try crossing angel wing begonia, a common houseplant, with another species. There is a good chance viable seed will be produced, according to Brian E. Corr, new crops development manager at Ball Horticultural Company, West Chicago.

The American Begonia Society (begonias.org) is a resource for information on hybridizing. The archives of the bi-monthly journal The Begonian would also be helpful.


Compost Bin

I’d like to start composting. Do you have any advice on what kind of bin to purchase/build so that it is successful in the Chicago climate?

Compost, decayed organic matter, improves soil structure, porosity and density and creates a better root system. It increases moisture retention and nutrients while adding significant quantities of organic matter to the soil. It is such a valuable addition to garden soil that it is worth the effort to collect and store waste vegetative material until it decomposes.

Compost bins range from low to high tech. A compost heap can be as simple as a pile of leaves stored at the rear of your garden. The most costly composter is a revolving two-tumbler device with a rotator drum that separates new material from finished material and discharges the final product.

Ideally, if you are saving a mix of unshredded plant material that includes flower stems, large leaves and small branches, a three-bin system works best. Stake out three 36-inch square cages using fence rails, lattice or steel wire. Raw material goes into the first bin. When it is partially decomposed, aerate it and shift it to the second bin, and put the most highly decomposed matter into the final bin. With that method, you can keep adding fresh material as the season progresses.

Do not put any diseased plants in the pile. Keep it in a concave shape to hold rainwater, and aerate it occasionally. As the pile “cooks,” it will heat up during the summer. An interior temperature of 180 degrees will kill bacteria but is not often attainable; 120 degrees is more likely for a mix of green and dried leaves.


Hibiscus

I am growing my potted tropical hibiscus indoors for the winter. The leaves are starting to yellow and fall off. Should I give the plant iron and should I fertilize it? Do I cut it back, and if so, when?

Hibiscus leaves turn yellow in response to the change in environment. The older leaves fall off first. If the leaves are chronically pale yellow with green veins, the plant could be lacking iron, but in your case, it is probably the change in growing conditions that is affecting the plant. When the days get longer in February or March, prune it to shape it, or cut it down to force good bottom growth.”

“Don’t panic; the plant expresses itself dramatically,” reassures Mike Geimer, owner of Geimer Greenhouses, Long Grove. “Don’t be timid pruning it.”


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.


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.


What three dwarf shrubs do you think gardeners should know about and why?

What three dwarf shrubs do you think gardeners should know about and why?

Evelyn Fink, garden center manager at The Fields on Caton Farm, Inc., Crest Hill

Yuki Cherry deutzia, Kodiak Black diervilla and Little Henry itea should have a presence in everyone’s garden. They will work well complementing taller shrubs in mass plantings and as a focal point when planted individually. All of them grow in full sun to partial shade with sizes ranging from 1½-4 feet. The itea will also grow in full shade. The unique shape and flower of each plant combined with the rich burgundy to wine-red fall color make these must-haves for plant lovers.

Mark Maradik, plant manager, Pasquesi Home & Gardens, Lake Bluff

The native Sugar Shack buttonbush (Cephalanthus occidentalis) thrives in wet heavy soils and clay. Fragrant pincushion-shaped white flowers attract pollinators. Red fruit in winter. Bobo is the best Hydrangea paniculata to date from Proven Winners. It is 2-3 feet tall and completely covered with long-lasting white flowers. The Low Scape Black Chokecherry (Aronia melanocarpa). Only 2 feet tall, tolerant of all soils; very cold tolerant. Profuse small white flowers in spring and dark purple fruit. Brilliant red/orange/ magenta fall leaves.

Jeff Schulz, owner, The Hidden Gardens, Willowbrook

My favorite dwarf shrubs have all-season interest and can be pruned to stay even smaller. Fothergillia gardenia (24-30 inches tall) is the smallest fothergillia cultivar. White flowers emerge in spring just before the leaves. Fall color is red, orange and yellow. Disease-free. Spilled Wine Weigelia (24-30 inches tall and wide) has dark purple leaves all summer if planted in full sun. Long-blooming pink flowers in spring, Deer resistant. Bobo hydrangea (30-36 inches tall and wide) produces loads of white flowers in mid- to late summer, changing to pink in fall. Flowers are held upright on strong stems and do not flop.


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.


Perennial Pinchback

Is there an overall rule about when to pinch back my leggy plants?

“The reason plants are pinched back is to obtain compact and bushier growth. This is generally done three times during a growing season, or you can apply the 6 nodes rule,” says Jennifer Brennan, horticulturist, Chalet Nursery, Wilmette.

After 6 weeks of growth, trim back half of the growth, or wait until you see 6 nodes on the plant stem to trim back to get more branching. For plants that respond, such as chrysanthemums, use the 6 node criterion.


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I start ‘Dragon Wing’ begonia from seed under grow lights. What other begonias can I use to cross-pollinate with the ‘Dragon Wing’ so I can collect my own seeds?

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