Q & A Time: Annual and Perennial .
When I see colonies of Coltsfoot pushing through the leaf litter or the remaining snow, or in full glorious yellow bloom along side the road where the snow and ice have melted, I know it's time for Q & A season. Garden and landscape questions are already cropping up.
In an effort to be as proactive as I can, I'm intuiting as many as I am able in a single column. I hope I'm on the mark with a lot of them. You can let me know or send me your questions.
Q1: I've noticed some of my rhododendrons have come out of this winter with scorching along the leaf margins. Is this a serious problem? What can I do to help the plants?
A: This sounds like winter injury. Rhododendrons are adapted to avoid losing essential moisture during winter. Surely you've noticed the leaves curled under and folded back during those extreme periods of cold. This is the way the plant arranges its leaves to best retain moisture. If they are not on the north side of a house or other structure, or protected from the drying effects of sun and wind, moisture is lost along the edge of the leaf blade first. This is indicative of stress, but is usually correctible. Before next winter, erect a simple screen for protection from sun and wind when the ground is frozen. Burlap or lath should suit the purpose. The dead tissue will not regenerate, but this protection along with providing good cultural care will insure that they will stay healthy and better withstand the stresses of next winter.
Q2: I'm interested in planting some borders around my gardens that will attract beneficial insects. Any suggestions?
A: Golden marguerite (Anthemis tinctoria); Cosmos, especially "White sensation"; Marigold "Lemon gem"; Tansy, the herb (Tenacetum vulgare);
Caraway; Dill; Fennel; Spearmint; Coriander. Tansy attracts the highest number of the greatest variety of beneficial insects. Consider, also, a buckwheat patch, nearby, but not as a border.
Q3: Is there a best way to fertilize a vegetable garden, and, do all vegetables need the same amount of fertilizer?
A: Yes, and the time has past. Remember the old adage, "Feed the soil, not the plants"? It has never been truer. Last fall was the best time to test the soil and see what it needed to best support this year's plants. You can still do it, but the soil won't have all those months to absorb all the nutrients. Manure applied last fall would have had the whole winter to break down within the soil. You should only apply well-composted manure at this time of the year. 5-10-5 or 5-10-10 fertilizers should be applied as soon as the soil is workable in the spring at a rate of 1 1/2 pounds per 100 square feet. Side dressing, or banding, with fertilizers should always be placed four to six inches from the plant.
The following plants require less fertilizer: beans, peas, radishes, watermelons and turnips. The ones that need more: cabbage and the other cole crops, tomatoes, sweet corn, beets, carrots, onions, celery and potatoes.
Q4: High populations of grubs seriously damage my lawn, and, foraging expeditions of moles and skunks in search of them make it more unsightly. I hear nematodes are a good alternative to chemicals. Any details would be appreciated.
A: The grubs in question are probably Japanese beetle grubs and European chafer grubs. The decision to treat with anything should really be based on taking a population count. Loosen and flip over a square foot of lawn. Examine the underside and roots closely. If you count ten or more grubs per square foot, treatment can be effective.
Choosing a biological control over a chemical one is favorable to all the beneficial insects and earthworms inhabiting your lawn. Heterorhabditis bacteriophoro and Steinernema glaseri are both aggressive species of beneficial nematodes that are very effective at colonizing and eliminating the various grubs in the lawn. The critical elements are soil temperature (at least 70 degrees F) and moisture. Rain or heavy irrigation is required after application. Fall is the best time to treat, since most grubs in the lawn now are mature and have done whatever damage they could.
Q5: Yellow sticky cards are used to monitor certain insect populations by attracting and catching them. Will yellow clothes also attract these insects?
A: You bet. When you are working in the flower or vegetable garden avoid wearing yellow or light blue. Yellow attracts white flies (a scourge to tomatoes, strawberries, potatoes, beans, cucurbits, greenhouses, houseplants and many flower species); blue attracts thrips (scourge to hundreds of plants especially in the flowering stage). Both of these insects cause damage from sucking as well as transmitting diseases.
Q6: Two years in a row striped cucumber beetles have killed some of my cucumbers, squash and pumpkins. How can I prevent these pests?
A: The foliar damage from the beetles' feeding is not killing your cucurbits. Rather, the beetles are infecting the plants with bacterial wilt disease, Erwinia tracheiphila. Use floating row covers early in the season. As soon as you notice diseased plants, rogue them out. Insecticidal soap would be my first choice to control these beetles. If all else fails, carbaryl (Sevin), malathion, or rotenone insecticides used early in the spring when they first appear will provide good control. Most importantly, rotate your crops.
The wilt disease overwinters in the digestive tract of the beetles in that very soil. The more snow cover, the more beetles, and, probably the more bacterial wilt. Rotate!! Map out a rotation plan and keep out cucurbits from that bed for at least two years. Longer is better. You have so many other choices. Tomatoes and peppers, peas, onions, potatoes, corn, beans and greens, broccoli and cauliflower are some of the choices and combinations. Just not any cucurbits.
Q7: Everything I read about growing vegetables says they require a full day of sun. Aren't there any that will grow well in partial shade?
A: Try growing an assortment of "cool season" vegetables such as broccoli, kale, cabbage, chard, kohlrabi, turnips, lettuces, spinach and peas. If you have a spot with five hours of sun you can also grow carrots, onions, parsnips, cucumbers, arugula, and celery. Several herbs will also do fine: bee balm, borage, chervil, chives, parsley, sage, coriander, and the mints including catnip, Remember, this mint family can be invasive.
Q8: I have a lightly wooded area with moist shade. Can you suggest an herb ground cover that I can successfully grow there?
A: From the floor of the Black Forest in Germany comes the answer. It is sweet woodruff, Asperula odorata. This hardy perennial is a favorite of mine and might well become a favorite of yours, too. It sounds ideal for your situation. Virtually weed and pest free, dark green whorled leaves make this herb very attractive even when not in flower. In May and June when it does flower, the canopy of starry white flowers and the sweet fragrance that emanates from this dense carpet have earned it the title Waldmeister in Germany - "Master of the Woods".
Sweet woodruff is hardy to zone 4. Put in plants (seeds can take 200 days to germinate) eight inches apart. They spread by underground runners. Divide and replant clumps each year and the area will be blanketed in a few years. You might just fall in love with this versatile herb of many qualities.
From The Garden of Ed. Submitted for publication in The Towne Crier on May 2, 2007
© 2007 Ed Mues. All Rights Reserved.