Frequently Asked Questions

Perennials often provide winter interest and texture in the winter landscape. It is best to remove weeds from the perennial garden in the fall. Cut back only the plants that are diseased or have an insect problem because disease and insects may over-winter in this debris and infest the garden the following spring.

Compost or mulch is used to help keep plants insulated from late spring frosts. We recommend putting down mulch after the ground freezes because the perennials will stay dormant longer in the spring. However, if mulch is put down before the ground freezes, it should be removed early in the spring, usually around April 1st; otherwise the perennials may start to grow under the mulch.

Even though trees and shrubs don’t require as much water as they do in the heat of summer, it is still very important to continue watering.

One inch of rain or applying one inch of irrigated water per week up until the ground freezes is best. Watering should be done at mid-morning to prevent ice build-up if the temperatures drop below freezing at night.

Applying fertilizer at the wrong time is a waste of fertilizer, time, and money, and may actually stress the plant.

Evergreens: Evergreens can be broken down into two groups for fertilizing. Pine, spruce, and fir put out new growth in the spring and stop growing by June. Discontinue fertilizing these trees by the end of June. Other evergreens, such as juniper and yew, grow through the middle of summer and can be fertilized into mid-July, but no later.

Most deciduous trees and shrubs will grow into mid-summer and will benefit from fertilizer through mid-July.

Perennials can be fertilized in the fall, but as August and September approach, be sure to use low￾nitrogen fertilizer, as this will enable the perennials to build up root strength going into winter.

Continue to fertilize annuals the entire growing season.

Wrap smooth-barked and young trees in the fall to minimize damage from sun scald. Sun scald can occur on sunny, cold winter days. The sun warms the tree on the south and southwest sides, causing sap to thaw. When the sun sets or goes behind a cloud or building, the temperature of the bark drops very quickly, causing the sap to refreeze rapidly, which damages the tissue in the area that had warmed up. The bark in this area will eventually slough off, leaving a scar or canker.

Cracks from sun scald can allow insects, fungus, virus, or other damage to gain an entry and begin the process of weakening the tree. As it will take many years to heal a crack, prevention is important.

Paper tree wrap or plastic tree guards will minimize sun scald. In late fall, wrap the material around the trunk, starting at the bottom, and fasten securely below the first set of branches. Remove the wrap in the spring, after the last frost. Wrap newly-planted or young trees each fall for two-to-five years, depending on the texture of the bark. Once bark is rough, the tree is mature and will no longer need to be wrapped.

To repair sun scald damage, cut the dead bark back to live tissue with a sharp knife, following the general shape of the wound; smooth off any sharp edges to facilitate healing. Wounds will heal faster when they are elliptical in shape, coming to a point at the top and bottom.

Do not use a wound dressing on the exposed area unless the wound is on an oak or elm.

Spraying with a fungicide may help prevent fungal infection.

Remember this easy formula: 10 gallons/inch/week.

Trees require ten gallons of water, per inch in diameter, per week. The easy way to water trees: five-gallon buckets. Keep watering after they drop their leaves in the fall until the ground freezes in the winter. Pay special attention to young trees and evergreens.

Drill five 1/8-inch holes in the bottom of five gallon buckets. $5 each at home improvement or hardware stores.

Place the buckets along the tree’s dripline where the roots are.

Fill the buckets with water and let it slowly drain out. The buckets make it easy to measure the right amount of water for your tree. For example: a young tree, 2-inches in diameter will require 20 gallons (4 buckets) per week.

Dormant season pruning is a good time to rejuvenate overgrown shrubs. Once all the leaves have dropped, it is easy to see the structure of the shrub and to correct any problems.

Do not prune early-spring flowering shrubs in the fall. Lilac, old-fashioned bridal wreath, rhododendron, azalea, and forsythia set their flower buds for the next season during the summer. T(/h)ese plants need to be pruned immediately after flowering to avoid removing next year’s blooms.

Shrubs, like spirea and potentilla, can be pruned down to eight-to-twelve inches. This forces them to re-grow, eliminating the hollow-centers that may develop with age. Thinning out one-third of the largest stems of red- or yellow-twigged dogwood will force new growth which will have better stem color than the mature stems.

Deer eat just about every kind of plant in the landscape, although they do have their preferences. Repellants do work to deter deer, and The University of Minnesota recommends several products. They have been proven effective in repelling deer, however, if the deer are starving; little can be done to prevent damage.