Dear Master Gardener:
Is rhubarb a native plant? What should I know to grow it successfully?
All plants, of course, are native somewhere. In the case of rhubarb (Rheum rhaponticum), it is native to Russia and named after the river Rha, today known as the Volga. It came to America with the British in the 17th century and was often referred to as “pie plant” because that was its most frequent use.
Although it can be grown from seed, most people buy rhubarb already started, either from a nursery or as a division from a friend’s existing plant. The best time to plant it is in early spring. Because it is a large, spreading plant, it needs space, at least a 3-foot square of rich, well-drained soil in full sun. Its rhizomatous root gets large and deep, so a hole two feet deep should be prepared for it. Do not plant it too deep: the crown should be just level with the soil.
Rhubarb is a heavy feeder and should be fertilized in early spring and again in midsummer. Keep it well watered. When or if white flower stalks appear, remove them promptly so that they don’t deplete the plant’s vigor. There are few insect or disease problems.
Although rhubarb is very tart, it is used largely in sweet things such as pies, cakes, sauces, muffins, and jams. Cultivars with red stalks are most popular because of their color while the greener stalks are rather lackluster. The red also tend to be sweeter. To harvest the stalks, hold them firmly, pull and twist. Do not use a knife. Remove the leaves promptly to avoid wilting of the stalk. The leaves are poisonous, high in concentration of oxalic acid. When ingested, the leaves cause cramping, nausea and even death. The stalks also contain oxalic acid, but in a lower concentration, and are harmless to most people, the exception being those with gout, kidney disorders and rheumatoid arthritis. A myth persists that rhubarb stalks also become lethal after midsummer, which is not true. They can be used all summer long but most people stop using rhubarb after early July both because there are then many other fruits available and to let the plant store up energy for the next year.
Dear Master Gardener:
Are marigolds edible and do they really act as a natural pesticide?
Marigolds, a native of Mexico, have been grown in gardens throughout the world for hundreds of years and are one of the most popular bedding plants in the United States. Calendula officinalis (pot marigold), Tagetes erecta (African marigold) and Tagetes tenuifolia (signet marigold) are edible. Pot marigolds have been reported to taste “tangy and peppery”, African marigolds “strong and pungent”, and signet marigolds “citrus-like or “spicy tarragon flavor”. It is important to correctly identify flowers before consuming them and to make sure they have not been treated with pesticides. The only way to ensure flowers have not been previously treated with pesticides is to grow them from seed or buy organically grown plants.
Although there is little documentation and research to back it up, some garden experts agree that French and African marigolds repel some insects and nematodes and they “must smell to repel”. Some garden experts also believe that French marigolds repel mosquitoes.
According to Iowa State University Extension, not only do marigolds not repel rabbits, deer or other animals, rabbits occasionally browse heavily on marigolds. Research studies there have also concluded marigolds are not effective in reducing insect damage on vegetable crops.
Dear Master Gardener:
I would like to purchase a bird bath for my garden and was wondering if some are better than others. Should placement be a consideration?
Providing water for birds can improve the quality of your backyard bird habitat and give you an excellent opportunity for bird-watching. Not only do birds need water to survive, they also use water for bathing, cleaning their feathers and removing parasites. The typical bird bath sold in lawn and garden shops (picture a concrete basin mounted on a pedestal) make nice lawn ornaments, but are not necessarily what is best for most birds. First, they tend to be too deep. Second, they can be hard to clean. Third, they can crack if left out during the winter.
When you choose a birdbath, look for one made of tough plastic that can be cleaned easily and won’t break if the water freezes. A birdbath with a gentle slope allows birds to wade into the water. If you want to make your own, you can use a garbage can lid, saucer-style sled, or even an old frying pan. The goal is to try to imitate a natural puddle as much as possible. Birds seem to prefer baths at ground level; however, if there are cats around, raise the bath 2-3 feet from the ground. To give birds footing, place sand in the bottom of the bath. If your birdbath is on the ground, you could place a few branches or stones so that they emerge from the water; then birds can stand on them and drink without getting wet (especially in the winter).
The best place to put your birdbath is in the shade near trees or shrubs. The shade will keep the water fresh longer and slow down evaporation. The trees or shrubs will provide nearby cover from predators. To really make your bath attractive to birds, provide moving water. You can purchase products that drip or spray water into a birdbath. Keeping your birdbath full of clean water at all times is the key to attracting a large number of birds to your yard. It is important to clean it every few days and clean it immediately if you see algae starting to form.
JUNE GARDEN TIPS
• Most houseplants can benefit from being moved outdoors now to a shaded, protected spot to soak up much-needed humidity.
• Plant warm season vegetables such as tomatoes, peppers and eggplants when evening temperatures stay above 52 degrees.
• Deadhead flowers regularly to encourage prolific bloom.
• Plant potted annual flowers and vegetables on cloudy days when possible to minimize transplant shock.
• About mid-month mulch most flowers and vegetables with 2-3 inches of biodegradable material such as grass clippings and chopped leaf litter. It will conserve moisture, insulate soil and help prevent weed seeds from sprouting.
• Feed your compost pile with fruit and vegetable scraps and trimmings—skins, peelings, etc. White paper napkins and paper towels can also be composted, as can torn-up paper egg cartons and dryer lint.
• Prune lilacs and forsythia soon after they are done blooming because they set next year’s buds by about mid-July.
• When tulips, daffodils and other spring-flowering bulbs finish blooming, it is tempting to get rid of unattractive leaves. If you want bloom next year, it is important to leave them until they are no longer green. As long as they are green, they are feeding the bulbs.
Crow Wing County Master Gardeners are trained and certified volunteers for the University of Minnesota Extension Service. All information given in this column is based on research and information provided by the university. To ask a question, call the Master Gardener Help Line at 218-824-1000, extension 4040, and leave a recorded message. A Master Gardener will return your call.
QUESTIONS OR COMMENTS?
Crow Wing County Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. All information given in this column is based on research and information provided by the University. To ask a question, call the Master Gardener Help Line at 218-824-1000, extension 4040 and leave a message. A Master Gardener will return your call.
UMN Extension Crow Wing County Master Gardeners’ Website: z.umn.edu/crowwingmgs
Visit our welcome page: http://cwcmastergardeners.areavoices.com/
“The Gardener’s Table:” will be available for purchase for $10.00 each at the following events this summer: Northland Arboretum’s Country Sampler Picnic on July 16, Nisswa Flower Show on July 30, Crow Wing County Fair from July 29 to August 2.