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Pines in Winter

This past spring I planted a lacebark pine (Pinus bungeana) in full sun. As winter began, the angle of the sun’s rays has caused the tree to receive, at most, 4 hours of sun. What are sun requirements of evergreens in winter?

In general, pines adapt to the winter weather by becoming dormant, says Susan Eyre, Rich’s Foxwillow Pines Nursery, Woodstock. It is the freeze and thaw cycle that is hard on a plant, not the loss of sun hours. In a January thaw, sap rises and then freezes, which can cause the bark to crack, but plants usually recover.


Frost

I have a Japanese maple that was hit by frost. Some of the leaves are curled and brown. Will they fall off and new leaves grow? Is there anything I can do to help the tree? What is the best method to prevent this from ever happening again?

Your tree will recover from the frost damage. Adventitious (secondary) buds at the nodes will send out new leaves. Make sure that your tree is sited correctly in a sheltered location and protected from harsh winds, advises Susan Eyre, Rich’s Foxwillow Pines Nursery, Woodstock. If your tree is fully leafed out and a hard frost is predicted, you could drape your tree with plastic, a tarp or some other covering overnight.


Powdery Mildew

My lilac had a grayish blight on the leaves this summer. What caused this and how can I prevent it?

Your lilac had powdery mildew, a common fungal disease. It occurs in late summer in humid weather, especially if your plant is located in a damp, shady area. While unsightly, it does not damage the plant since it only affects the outermost leaf cell layer. If it really bothers you, spray the leaves with a sulfur fungicide early in the season. If mildew appears late in the season, spray again.

Newer varieties of lilac are more disease resistant than the common lilac. Improving air circulation by pruning out any dead branches will also help to reduce mildew, advises Joan Barczak, owner of Blumen Gardens, Sycamore.


Rose of Sharon - Botrytis Blight

I have two 3-year-old rose of Sharon plants, about 20 feet apart. One blooms every year. The other plant forms about 100 buds and looks healthy, but it has not bloomed in the last two years. The buds are solidly closed and look as if they are rotting from the inside out. There does not seem to be any sign of insects on the plant. What is this problem?

From the description it sounds like your plant is infected with botrytis blight, a fungus disease that attacks buds before they open, according to Jim Schuster, extension educator, horticulture, University of Illinois. Your plant needs to be treated with a fungicide early in the season. Remove all diseased portions of the plant and any residue on the ground, as the fungus lives over winter in discarded material.


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 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.


Rose Rosette Disease (RRD)

What is rose rosette disease? I lost two antique roses and removed a hedge of multiflora roses that were supposed to be undesirable. How bad is it?

Rose rosette disease is a plant killer of unknown origin and no known cure. It is known to plant pathologists, but unknown to most rose gardeners in this area.

The disease is believed to be caused by a virus or virus-like pathogen that has been spreading through much of the wild rose population in the Midwest, probably transmitted by a mite introduced to the U. S. to eradicate multiflora roses. It is lethal to the wild multiflora rose and potentially lethal to many rose species and cultivars.

Symptoms of rose rosette disease are highly variable, depending on the species or cultivar. Some of the more recognizable symptoms include rapid elongation of new shoots forming witches brooms, or clustering of small branches with distorted leaves of conspicuous red pigmentation and distorted flowers.

David Robson, Springfield, extension educator, horticulture with the University of Illinois, reports that it is all over our area. Mike Geimer, owner of Geimer Greenhouse, Long Grove, reports coming across RRD in a Long Grove garden. One plant in a bed of Flower Carpet roses caught his eye because of its uncharacteristic red clumping stems. He looked up the symptoms on the internet, identified it as RRD and advised immediate removal of the plant. Also important, warns Geimer: “Always sterilize pruning shears.”

Kathy Hallgren, Sycamore, is worried about the future of old roses. Two summers ago she noticed some peculiarly rampant irregular, hyper-thorny pink growth with irregular leaves on an antique Alba rose.

After researching the symptoms, Hallgren determined the irregularities were from RRD. “I dug out the plant and burned it. Once I learned that multiflora roses could be the culprit, I removed them even though they were healthy. This summer I saw it on one of my ‘William Baffin’ roses so cut it down and burned it. This disease means business,” says Hallgren.

No effective control is available for existing rose rosette disease. All cultivated roses are potentially susceptible. Be on the lookout for it. Early detection is the key to effective cultural control. If the disease is recognized early and the rose is removed, it is possible to save other roses in the garden and hopefully curb the spread of RRD.


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.


Bulbs Over Winter

What is the best way to dig up, clean and store gladiolus and dahlias? What are the little white sacs on glad bulbs?

Gladiolus corms and dahlia tubers are generally dug up after the first frost or before Halloween. Cut off all the stems and foliage, let the plants dry, and shake off all the soil. Make sure each corm and tuber is firm and not rotted. Place them in a box or tray and cover with peat moss. If you know the cultivar name, tag the plant.

Store them in a dark, cool place, checking them over winter. If the dahlia tubers are shriveled, sprinkle a little water on them. Dahlias can be potted up in spring for an early start in the garden.

“The white sacs you see attached to the gladiolus corms are little bulblets. You can remove them or not. If left on the corm, they will grow larger, and may enhance the number of stems on the plant. If you remove them and plant them, it will take at least three years before they flower,” explains Joni Cotton, perennial manager, Hawthorn Gardens, Hawthorn Woods.


Types of Fruit Trees

I am going to be planting five dwarf fruit trees; two ‘Bartlett’ pears, one ‘Cresthaven’ peach, and two ‘Honeycrisp’ apples. Could you give me some feedback on them?

If you buy young container fruit trees, plant them very early in the spring to lessen transplanting shock (as soon as the soil can be worked and before the buds break). Plant the tree at the level it was in the pot, adding a layer of top mulch.

“Wrap the trunk in paper or plastic tree wrap to prevent deer and rabbit damage. Protect the trunk from voles with fine wire mesh at the base,” says Tim Norris, president of Spring Bluff nursery, Sugar Grove.

‘Bartlett’ pear is subject to fire blight and also needs a pollinator for good fruit production. ‘Patten’ and ‘Parker’ are two pear cultivars Norris recommends. Two different cultivars will give you better cross-pollination.

‘Honeycrisp’ apples are an excellent choice for this area. They grow up to 20 feet tall on semi-dwarf root stock. They can be pollinated by any member of the Malus family, including a nearby flowering crab tree.

‘Cresthaven’ peach, while hardy here, may not bear fruit, depending on how cold the winters are. When the temperature goes down to zero, ‘Cresthaven’ peach loses all its flower buds. Norris suggests growing ‘Reliance’ peach instead. It needs a long growing season. Last spring (2008) was a cool one and peaches did not bear much fruit. Peaches are not long-lived trees. By the time the tree is bearing fruit, you will need to start growing another tree.


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questions

When does each issue get mailed out?

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.

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.

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