I have a nicely sheltered, rounded 7-foot tall Japanese red maple on the southeast corner of my backyard. Half of the tree has lost its leaves, the formerly red bark is turning gray, and a good-sized square of bark has been stripped off on the side that faces the yard. I sprayed the exposed bark with black pruning spray to close any entry for insects. I have not cut off any of the branches.
Does the winter have any effect on the tree? Should I look for some insect infestation? What should I do now?
“It appears that the tree suffered some kind of injury. Over winter, watch for sun scald on the southern exposure. Use paper tree wrap on the trunk,” advises Mike Geimer, owner of Geimer Greenhouse, Long Grove. If you are fearful of insects, you can use an organic pyrethrum spray. Black pruning spray is not necessary.
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.
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.
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.
“I suspect that your watering every two weeks was not sufficient and that your tree was going into early dormancy,” says Chicagoland Gardening editor Carolyn Ulrich. “It was very dry late in the growing season and a lot of trees looked stressed.”
A rule of thumb for watering is one inch per week. Heptacodiums grow best in moist soil. You probably needed to increase the amount of time the water was on the plant and also water more frequently. Soaker hoses can run for hours.
If you want to figure out how much water your tree is receiving, use a sprinkler, if you have one, and run it on your tree until a tuna fish can has an inch of water in it, and then stop. Do this weekly, unless it rains.
What is the correct distance from my house to plant a tree? What is the correct distance from the lot line to plant a tree?
It depends on the size of the tree you are planting. A small tree such as a serviceberry (Amelanchier) or a dwarf flowering crab could be planted as close as four to five feet from the house. For a birch tree, a distance of six to eight feet would be the minimum.
Distance from the lot line does not matter as long as it doesn’t interfere with power or sewer lines. You should check with your village before planting. Closeness to the neighbor’s lot line is not an issue, because neighbors have the right to trim back any overhanging branches, according to Matt Zerby, partner in Wasco Nursery, St. Charles.
What is the largest tree that one can plant? We are trying to replace some 7- to 8-foot trees that were recently destroyed.
Trees sold at garden centers that are 2.5 to 3 feet tall, with a 2.5 inch diameter trunk, can be planted by hand. A hole for a ‘balled and burlap’ tree with a 5 to 6-inch diameter trunk can be dug by hand without a tree spade.
Any tree with a trunk larger than 6 inches in diameter would need a tree spade to do the moving and digging. Even large trees, such as a 35-foot tall tree with a trunk 9 or 10 inches in diameter can be transplanted with proper equipment. “Spruces 30 feet tall can be installed easily with a tree spade,” according to Greg Oltman, owner, Gro Horticultural Enterprises, Huntley.
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.”
Miniature gardening is the rage. What enchanting miniature plants work well in a shaded area?
Many miniature plants grow in shade. Some unusual ones are the 6-inch tall Solomon’s seal (Polygonatum humile ‘Tom Thumb’), the 2-inch tall Ajuga reptans ‘Planet Zork’ and two cultivars of the very slow-growing conifer Cryptomeria japonica: ‘Koshyi’ and ‘Tenjan’. Or look for two European gingers, Asarum forlesii ‘Mercury’ and Asarum takaoi ‘Roundabout’, which are about 3 inches tall. Also: the maidenhair fern (Adiantum venustum), mosses and miniature hostas
The best and most obvious answer is miniature and small hostas. From the ever-expanding “mouse” series with ‘Holy Mouse Ears’, ‘Mighty Mouse’ and ‘Giantland Sunny Mouse’ to newbies such as ‘Mini Skirt’, ‘Ladybug’, ‘Baby Booties’ and ‘Little Starlet’… perfection! Add some grass-like carex such as ‘Beatlemania’ for texture, miniature Solomon’s seal (Polygonatum humile) and dwarf heucheras from the Little Cute series, and your garden fairies will be in heaven.
If you’re planting in the ground, these low-growing perennials will add interest and texture to your garden: Irish and Scotch moss (Sagina sublata and S. subulata ‘Aurea’ – best in part shade), brass buttons (Leptinella squalida) and miniature hostas. Add color with annuals such as polka dot plants (Hypoestes), ‘Strawberry Drop’ coleus and torenia. It’s important to add perennials and annuals into your garden for a longer season of color.
Besides mums, what are a few other plants you would recommend for containers for fall color?
Dwarf or miniature sunflowers add a bright, sunny pop of color to any container. Mix them with pink celosia, ornamental kale, dwarf ornamental grass and ornamental peppers for a special autumn arrangement. The kale is a great addition as the colors get brighter with colder temperatures. Ornamental pepper can also be taken in and kept as a houseplant through the winter months. Or use aster through October and plant in the garden before the soil freezes. Comes in many colors.
The rudbeckias ‘Indian Summer’, ‘Prairie Sun’ and ‘Becky Cinnamon Bicolor’ all have beautiful large flowers. Herbs and leafy vegetables like Swiss chard ‘Bright Lights’, mustard ‘Red Giant’, bronze-leaved fennel and variegated sage all add fun textures. Plectranthus ‘Mona Lavender’ combines nicely with ornamental kale and cabbage. Also plant trailing pansies like those in the ‘Cool Wave’ series at the edge of planters and hanging baskets. Another creative way to add interest to fall planters is with preserved and dried botanicals, sticks or accents.
Our favorite addition to autumn containers – hands down – is ornamental kale. As the temperatures drop, the leaf color intensifies and the plant actually becomes more attractive. We frequently pair ornamental kale with late season grasses as well as decorative gourds and squash tucked amongst the foliage to celebrate the abundance of the harvest season. Your visitors may still be enjoying your kale peeking through the early snow on Thanksgiving Day!
I would like to start seeds under lights. When is the best time to start flower seeds? The seed packet always says to sow a number of weeks before the last frost. When is the last frost?
“In this area we use May 15 as a benchmark for the last frost date, but it can be earlier or later,” says Chuck Prosek, grower at Prosek’s Greenhouse, Winfield.
If your seed packet gives you the number of days to germination, add that to the number of weeks for growth, and then count the number of weeks back from May 15. Tomatoes sown indoors generally need 6-8 weeks of growth before being set out.
Many seed packets do not include germination time. A good guess is to allow 1-2 weeks for the seeds to germinate, but if you use bottom heat, your seeds will germinate earlier and grow faster. Most seeds need warm soil of 65 to 70 degrees to germinate and grow.
When you sow seeds directly into the soil, till the upper inch of soil to loosen it for direct seed to soil contact. The outside soil temperature must be above 50 degrees for cool growing plants, and at least 65 degrees for warm season annuals, according to Prosek.
For future reference, keep a record of indoor sowing dates, germination dates, length of indoor growing period, and transplanting dates.
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?
Where can I order a media kit?
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?