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.
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.
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.
Now that bedding impatiens (I. walleriana) are not recommended because of impatiens downy mildew, what are three good annuals for shade?
Chris Williams, production manager, K&W Greenery, Janesville, Wisc.
I like New Guinea Impatiens. They make nice bushy plants that are full of large colorful flowers and are easy to grow. You also get a large color selection with New Guineas. The SunPatiens and Bounce impatiens are fairly new plants, and they are recommended for sun as well as shade. Then there’s coleus. Who doesn’t like its colorful foliage? Many varieties grow upright, but others also spread. Torenia, also known as wishbone flower, has trumpet-like flowers of white, yellow, rose and purple that cover nicely mounded, low-growing plants.
Karen Wedel, manager of the outdoor floral department, Wedel’s Nursery, Garden Center, Kalamazoo, Mich.
One of my favorites is begonia. Tuberous varieties have large colorful blooms; wax begonias are good for mass planting. I’m also a fan of the big leaf, 16-20 inch tall Whopper series with large waxy leaves and summer-long flowers.
Another idea is coleus and caladiums. They come in different foliage colors, work great in gardens and containers. They are both also easy-care.
Finally, torenia or wishbone flower, named for the small “wishbone” inside the mouth of the pink, yellow or blue-purple flowers. Blooms all summer. Some varieties will trail.
Kevin DeBoer, manager, Big John’s Farm Market and Greenhouse, Chicago Heights
My favorite is Dragon Wing begonias. They’re usually sold in 4½ inch pots or hanging baskets. At my house I removed them from the baskets, then planted them in the ground in full shade. They turned out awesome! Plain wax leaf begonias are also good.
In addition, I like coleus. They don’t produce flowers, but they have many different vibrant leaf colors. In full shade New Guinea Impatiens will flower sparingly, but if you put them in some sun, they will flower more.
What are your three favorite “all-but-forgotten” perennials that every garden should include? Why do you like them?
Anemone tomentosa ‘Robustissima’ is a late season plant for sun to part shade and a wide range of soils. Deer and rabbit resistant with few pests or diseases. The fuzzy texture and gray-green leaves of Stachys byzantina ‘Helene von Stein’ complement other sun plants wonderfully. Leaves mask brown lower foliage of asters. The 3 to 5-foot tall Baptista australis and PRAIRIEBLUES cultivars offer gorgeous blue and purple flowers and they attract butterflies. They like full to part shade and tolerate poor soils.
My three favorite forgotten perennials are plumbago, bergenia and Stokes’ aster. Plumbago (Ceratostigma plumbaginoides) is a ground cover with sky blue flowers in fall and red leaves. Intersperse it with spring bulbs for three seasons of interest. Bergenia (Bergenia cordifolia) is versatile, handling conditions from moist sunny areas to dry shade. It is rabbit and deer resistant. When you rub your two fingers on either side of the leaf you can make it squeak (hence another common name: pig squeak). The long-blooming and easy-care Stokes’ aster (Stokesia laevis) is fairly pest and disease free. Rabbits tend not to eat it, and it attracts butterflies.
Three favorites of ours are pasque flower (Pulsatilla vulgaris), Laddie peony (Paeonia peregrina) and balloon flower (Platycodon grandiflorus). Pasque flower blooms very early in spring with extremely soft leaves and silvery green buds. Red, white or purple flowers; purple seems to have more vigor. The ferny-leaved Laddie peony also blooms very early with red flowers. It’s a hybrid of Paeonia peregrina and P. tenuifolia. Balloon flower is named for blue, pink or white flowers that start out looking like a balloon and open to look like a star. They have a long blooming period in summer.
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.
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.
I am interested in improving fall color in my yard. What shrubs turns red beside burning bush (Euonymus alatus)?
Wendy Vichitk, plant manager at Luurs Garden and Flower Shop, Hillside, recommends these shrubs for a colorful fall garden:
Low growing 2- to 3-foot Virginia sweetspire ‘Little Henry’ (Itea virginica) has red foliage and grows in both sun and shade. The foliage of the somewhat taller ‘Henry’s Garnet’ is dark red, as the name indicates.
Fothergilla ‘Mount Airy’ has blue-green leaves that turn intense yellow and orange-red in sun and half shade.
Oak leaf hydrangea (Hydrangea quercifolia) grows in shade or partial sun, with orange-red to red fall color.
The leaves of apple serviceberry (Amelanchier grandiflora) burn a bright orange red. There are several cultivars on the market to choose from.
Many viburnums have bright fall color. The easy to grow Korean spice viburnum (Viburnum carlesii) and the also fragrant V. juddii have leaves that produce a mixture of red, orange and mahogany. Arrowood viburnum (V. dentatum) and cranberry bush viburnum (V. trilobum) both exhibit typical red-purple color.
The intensity of color is affected by the weather. Warm sunny days followed by cool nights bring the highest leaf color. The health of the plant, its growing conditions, and the amount of water the plant receives also affect fall color.
What is the green worm that eats my roses and columbine every year?
It is hard to diagnose your problem without seeing the caterpillar. There are several green worms that bother roses, and one can be controlled with Bt (Bacillus thuringiensis) but rose slug, for example, cannot. Proper identification is necessary before applying any control method. Do not use an insecticide for anything that"s not on on the product label. Do not use any insecticide as a preventive measure. It doesn"t work and ends up being harmful to the environment and a waste of your money.
Green worm on your columbine could be an inch worm or canker worm. If the caterpillar loops up in the center or arches as it moves along, it could be a looper or cabbage worm. Leaf miners, which are usually white or pink, tunnel in the leaves. “To eliminate insects, use insecticidal soap,” said Nancy Clifton, Chicago Botanic Garden Plant Information Specialist.
For an exact diagnosis, consult your local University of Illinois Extension service or collect a specimen and bring it to the Plant Information Service at the Chicago Botanic Garden or the Morton Arboretum.
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.
I have houseplants outside that I will need to bring indoors. What is the lowest temperature at which I can leave them outside?
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?
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