Ask the Master Gardener: A smelly alternative to stop deer from feasting on plants

Cimicifuga is among numerous plants rarely eaten by deer. Photo by Jennifer Knutson

Dear Master Gardener: All my hostas were eaten by deer this year. Are there plants I can add among them that will repel deer? Besides physical or chemical barriers, are there plants that act as deer protection?

Answer: If your hostas are being eaten by deer, it can be assumed that this is a shade garden. According to the University of Vermont Extension, deer repellent plants are those that are highly aromatic and therefore offensive to them. They suggest interplanting perennial herbs such as Artemisia, Tansy and Yarrow and culinary herbs such as Mint, Thyme, Tarragon, Oregano, Dill, or Chives as a repellent. Unfortunately, herbs require a sunny location, so this may not be an option for you. There are plants that deer typically dislike and avoid, such as plants with fuzzy or coarse foliage and those with leaves or stems with strong odors. Plants for a sunny garden that are rarely damaged by deer include Anise Hyssop, Autumn Crocus, Catmint, Allium, Russian Sage, Baptisia and most herbs. Plants for a shade garden that are rarely eaten by deer include Pulmonaria, Lady’s mantle, Wild Ginger, Ferns, and Cimicifuga.

Dear Master Gardener: Can I bring my herbs inside for the winter so I can continue to have fresh herbs for cooking?

Answer: Yes, but it can be challenging in the hot, dry conditions found in most homes in the winter. Herbs grown indoors will probably be less productive than when they are grown outdoors. Bring potted herbs inside before the first frost. Some herbs, such as chives, mint, and tarragon can tolerate a light frost. Keep herbs in a room that has daytime temperatures of at least 65-70 degrees and nighttime temperatures of 55-60 degrees. Most herbs need at least six hours of direct sunlight, so give them as much light as you can by placing them in a sunny, south-facing window or under cool white fluorescent lights for 14-16 hours. If you are growing potted herbs on a windowsill, rotate the pot for uniform growth. If herbs do not receive adequate light, they will become thin and spindly, produce smaller leaves, and have less aroma. You can increase humidity by setting the pots of plants on saucers with moist pebbles or misting them with water. Water only when the potting medium feels dry, but never allow the plant to wilt.

Dear Master Gardener: My husband is always in a hurry to cut back perennials and clean up the gardens. Is it too early to cut them back? Can they be cut back in spring instead?


Answer: Wait to cut back perennials until their foliage is damaged by frost and they are brown and dead. As long as the plant is green, it continues to build up carbohydrates through photosynthesis and store them in its roots for next year’s growth. Many perennials do not need to be cut back at all before winter and some provide beautiful winter interest and a source of food for birds. Ornamental grasses and perennial seed pods, such as those found on Baptisia, can add striking interest to a winter landscape. You can leave them standing until spring then cut them back before new growth appears. Many birds rely on the seed heads of dried perennials for food. If you would like to provide a food source for birds, leave Rudbeckia (black-eyed Susan), Echinacea purpurea (purple coneflower), and Heliopsis in place for the winter. As we experienced last winter, we can have some very frigid temperatures. Perennials that are hardy to zone 4 are more likely to survive our cold winters if you don’t cut them back, which allows leaves to collect around them and snow to insulate them.

It is important to cut back any plants with disease or insect problems to reduce the chance of infection next year. If you had problems with slugs around your hostas, cut them back as soon as they are frost-damaged and remove all their leaves from the ground, as the dead leaves can harbor slug eggs that will hatch next year. Cut back Peonies within two inches of the ground when they have been damaged by frost and are mostly brown. Heuchera (coral bells), Dianthus, Moss Phlox, Hellebores, and Tiarella should not be cut back.

Dear Master Gardener: Should I cut my Hydrangea back this fall or wait until spring?

Answer: Hydrangea arborescens (Annabelle, Bounty, Incrediball, Grandiflora) and Hydrangea paniculata (Limelight, Quick Fire, Pinky Winky, Tardiva, White Diamonds, etc) bloom on new wood of the current season. They can either be cut back in late winter or early spring. Flowering is actually enhanced by cutting back all stems to about 12 inches from the soil line. Some hydrangeas flop after a rain. One way to alleviate flopping and strengthen the stems is to cut stems to a height of 18-24 inches to provide a framework to support new growth. Some Hydrangea paniculata can grow quite large so cutting it back can help you manage its size. If size is of no concern to you, then just remove spent blossoms and any broken stems.

October Gardening Tips

  • Gradually reduce mowing height to 2 ½ inches until grass grows dormant. If grass is left long through the winter, it will fold over under the weight of snow and form humid pockets that will favor the growth of snow mold. Most mowers do a good job of mulching tree leaves if they aren’t too thick, but heavy accumulations of large oak and maple leaves should be raked up and composted.

  • If nights with freezing temperatures are predicted, cover annuals such as begonias and impatiens loosely with sheets to trap the heat stored in the ground overnight and prevent freezing damage. Sometimes when plants are protected for one or two nights they will keep growing and blooming for an additional few weeks.

  • Tropical plants, such as Mandevilla and Hibiscus, have no frost tolerance and must be brought indoors before any freezing temperatures occur. If you would like to keep them over the winter, place them next to a patio door or large window where they will receive bright light.

  • Cover strawberry plants with clean straw after several nights of temperatures in the mid 20s to allow them to go dormant and protect their crowns.

  • Vegetables in the cabbage family (kale, kohlrabi, broccoli, and Brussels sprouts) develop a milder flavor when exposed to a frost before harvesting.

  • Plant tulips, hyacinths, and miniature daffodils in shallow containers to force for winter bloom. Place the containers in a cool dark place for about three months; then move them to a bright, sunny spot for three to four weeks to flower. Bulbs started in mid-October should be blooming by mid-February. Paperwhite Narcissus bulbs do not need a cold forcing treatment and will bloom in a few weeks from when you plant them.

  • Keep watering trees and shrubs -- especially evergreens -- until the soil freezes. They need sufficient water to survive our dry winters.

  • Clean up and dispose of fallen apples, apple leaves with spots, over-ripe vegetables, and tomato plants that had disease problems and do not compost them. Many disease and insect pests overwinter in plant material and good sanitation will reduce pest problems next year.

University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. All information given in this column is based on university research. To ask a question, call the Master Gardener Help Line at 218-454-GROW (4769) and leave a recorded message. A Master Gardener will return your call.

Pulmonaria is a variety of plant not often eaten by deer. Photo by Jennifer Knutson

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