In gardening, winter is defined as the time of year when most perennials become dormant. This time can vary from early September in some parts of the country to late December in others. Cold is the major factor inducing plant dormancy. Thus, in preparing for winter, it's crucial to understand just what kind of cold affects your garden.
If chilly weather in your area means blankets of snow, you're in luck. Snow, sometimes called a "poor man's mulch," forms an insulating blanket on the garden. Temperatures in the ground beneath the snow cover always hover around 32 degrees F, while they can plunge far below 0 degrees F immediately above the snow line. Perennials that are dormant at a constant temperature rarely have trouble surviving winter months. Use this guide to protect your precious perennials this winter!
Cut back dry stems of perennials to soil level after frost to neaten the garden and remove pest eggs and disease spores that may linger. Leave stems with attractive seed heads for winter interest. Compost dead plant debris to create an organic soil conditioner. Hot, active piles kill weed seeds and disease pathogens; passive, inactive piles do not. Throw questionable plant material in the trash.
Mulch perennial and shrub beds with pine needles or chopped leaves. This protects both plant roots and the soil and moderates the effects of extreme temperature changes during winter freezes and thaws.
Gardening Tip: To prevent rodents from nesting in the soil, wait until the ground freezes before adding a 6-inch layer of organic material as winter mulch.
Preparing Warm-Climate Perennials
- Divide spring- and summer-blooming plants.
- Continue checking plants for pest infestations and disease outbreaks. Identify and deal with any factors that may be stressing the affected plants and making them vulnerable to these problems.
- Clean up perennial beds and borders. Cut down dead flower stems. Dig up and remove diseased plants. Weed areas that weren't mulched.
- Divide overlarge clumps of spring- and summer-blooming plants to control their size and renew their blooming.
- Dig new beds and renovate existing ones. Plant new perennials and transplant others.
Preparing Cool-Climate Perennials
- After the ground freezes, spread a winter mulch over any bare soil in the garden. Spread evergreen boughs over beds.
- After frost, clean up perennial beds and borders. Cut down dead flower stems. Dig up and discard any weeds and diseased plants.
- Build a cold frame to overwinter marginally hardy perennials and provide a chill period for bulbs being forced for winter bloom.