ASK A MASTER GARDENER
Spiders most likely not culprits of biting
Dear Master Gardener,
I think I may have some spider bites on my arm and was wondering if I should spray my whole house to prevent spiders from coming in?
It is common to think that a skin irritation could be a spider bite, but few spiders bite and most are harmless to humans. Even the feared black widow and brown recluse spiders are not aggressive and shy away from people, but you won’t have to worry about it because neither one is native to Minnesota. Spiders can enter your home any time during the year; however you will be more likely to find them in late summer and fall when they are looking for winter hibernation sites. You are also more likely to find them in homes located by rivers, lakes or fields. If possible, try to tolerate spiders because they are very beneficial to the environment and consume lots of insects, including pest insects. If tolerating them in and around your home is not an option, then try to use a nonchemical method first. Regular housecleaning is very important in controlling spiders in your home. Other ways to reduce the number of spiders in your home are:
• Remove papers, boxes, bags and other clutter to minimize favorable sites for spiders.
• Remove webbing with a broom or vacuum, and destroy any egg sacs and spiders that are found. Look especially around windows, in corners and other relatively quiet places.
• Eliminate insects that serve as a food supply, especially when large numbers exist. Check particularly in and under webs to see what insects have been captured.
You can supplement your sanitation efforts with an insecticide treatment applying it behind base-boards, in cracks and crevices and other places where spiders may hide. According to the entomology department at the University of Minnesota general treatments on surfaces and fogs are not effective. Most insecticides labeled for ants and cockroaches are also labeled for spiders. These products are commonly found in aerosol ready-to-use cans.
Before using chemicals, you could try the following outdoor control:
• Remove piles of bricks, firewood and other debris that may serve as suitable homes for spiders or move them further from your home.
• Keep grassy or weedy areas near buildings cut short.
• Trim back shrubs and other plants that directly contact your home.
• Knock webs down with a broom or a hard spray of water.
• Remove and destroy any egg sacs or spiders that are found.
• Caulk or seal obvious cracks or spaces around the foundation, doors and ground level windows.
• Check to be sure screens fit tightly. Replace any screens that fit poorly or are damaged.
• Change outside lights to reduce insect prey that can encourage spiders. Yellow lights are less attractive to insects than mercury or sodium vapor lights.
If it is absolutely necessary, supplement these methods with an insecticide application around the outside of your home. Spray under your siding, in cracks and crevices and other places where spiders may hide. General treatments on the siding or other surfaces are not as effective. If you decide to treat the outside of a building with an insecticide, the University of Minnesota recommends either chlorpyrifos as a liquid concentrate or a liquid ready-to-use product, or diazinon as a liquid concentrate.
Caution: Read all label directions carefully before buying insecticides and again before using them. The label is the final authority on how you may legally use any pesticide.
Dear Master Gardener,
How do you divide peonies and when should you cut them down for the winter? Also, can balloon flowers be divided?
When it comes to peonies (Paeonia) it is important to place them carefully because they do not like to be disturbed. With that said, they can be divided by digging up the entire clump, then splitting it into halves or quarters with a sharp knife or shovel. This can be a challenge because the roots are thick and brittle. Keep in mind the smaller the division, the longer it will take for them to bloom again. Proper planting depth is critical because if they are planted too deep your plant may bloom very little or not at all. Try to divide any perennials four to six weeks before the ground freezes so the plant’s roots become established. It is important to remember not to cut down peony foliage until it is damaged by frost.
Balloon flowers (Platycodon grandiflorus) also do not like to be disturbed. They have a gnarled, brittle root system and dividing them is not recommended. If you decide to try and divide your balloon flower it will most likely not bloom for a year or two after division.
Dear Master Gardener,
I need fall color in my perennial garden and am considering asters. What care do they need?
Asters would be a good choice for fall color. They come in red, blue, purple, lavender, white and many varieties are hardy in our Zone 3. They grow in average garden soil in full sun to partial shade. Asters grown in full sun are bushier and have more blossoms than those in partial shade. In June the plants should be pinched back to about 6-inches to keep the plant bushy and to prolong the bloom. They multiply easily and therefore need to be divided every three to four years. They like regular watering and make good cut flowers. Asters are usually very healthy under their preferred growing conditions but sometimes do get powdery mildew. To avoid that problem, choose mildew-resistant varieties, give them full sun and provide good air circulation.
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 824-1000, extension 4040 and leave a recorded message. A Master Gardener will return your call.
October garden tips
• It is normal for pines, spruce and arborvitae to drop many yellow or brown needles at this time of year. It’s part of their normal growth cycle.
• Plant tulips, daffodils and other spring-blooming bulbs this month. How deep? Two to three times their vertical diameter. Water every week until the ground is frozen.
• To minimize snow mold next spring, gradually reduce fall mowing height to 2 ½ inches. Longer grass will fold over, forming moist pockets that encourage snow mold growth. Continue to water regularly until the ground freezes.
• Remove frost-damaged annuals and consider replacing them with ornamental kale and cabbage for continuing fall color.
• Instead of bagging leaves, mulch-mow them in place and leave them on the lawn. They will decompose and add nutrients to the soil.
• Cabbage, kale, Brussels sprouts and kohlrabi improve in flavor after a frost.
• Hardy shrub roses need little winter protection. Just rake leaves over their roots.
• Tender roses can’t tolerate temperatures lower than 20 degrees Fahrenheit. Plan to protect them by mid-October even if they are still blooming.
• To prevent the spread of plant diseases and pathogens, empty plant containers and wash them in a 10 percent bleach solution. If possible, submerge them in the solution for 30 minutes and scrub them with a plastic brush or scrubber. Be careful not to splash bleach water on clothing. Rinse and store containers in a dry place.