The Circle of Life of Tender Annuals

When the seasons change and colder weather arrives, there are a few steps you can take to protect tender plants from winter injury or a freezing death. Keep in mind that many flowers and vegetables are considered tender annuals and this means they are planted to be enjoyed for just one season and replaced annually. The first hard frost will end their natural life cycle and so don’t feel bad about adding the yellowing, autumn remains of annuals to the compost pile or digging frost-bitten plants into the ground so they can compost in place over the winter.

Protecting Tender Annuals

You may be able to cover an annual display with a sheet or light covering and protect them from the first cold nights of autumn. Just don’t expect these heat loving plants to make it through a cold winter even with protection, these include: coleus, marigolds, petunias, zinnias, and many other flowers that you may think of as ‘bedding plants.’ In the vegetable garden tender tomatoes, peppers, squash, beans, eggplants, and many edibles you may think of as ‘warm season crops,’ can be protected for a few extra weeks but not all winter long.

Keeping Tender Annuals Alive a Bit Longer

First, pay attention to the weather forecast. If the night temps are predicted to sink below 45 degrees, water the soil well the night before. Damp soil produces humidity and this helps protect the plants from cold. Next, use a sheet or other light fabric to drape loosely over your tender plants and secure the edges with bricks or stakes. Be sure to remove the covering once the sun comes out to avoid suffocating the plants.

Protecting With Reemay – Agricultural Cloth

You can cover rows of vegetables and flowers with bolts of the lightweight polyester fabric, trade name: Reemay (order online or from local nurseries). This will protect them from freezing until the temps are below 28 degrees. You do not need to remove this blanket of protection during the day as it allows rain and air to pass through the barrier. Reemay is often used by organic farmers in the spring to protect crops from pests and as a season extender in the fall to keep vegetables producing into the winter. In vegetable gardens the Reemay is tacked to hoops that emerge from the ground to keep the fabric from resting on the plants.

Protecting Tender Bulbs

Cannas, gladiolas, dahlias, tuberous begonias, and in some colder parts of the country, calla lilies, agapanthus and eucomis (or pineapple lily) are examples of summer bloomers that need winter protection if you want them to survive.

Protecting Tender Bulbs by Digging Them Up

Once a bit of cold weather turns the foliage of a tender bulb gold or brown, this is your signal to dig in and uproot the bulb-like root growing underground. Dig a circle around the area where the roots are growing and then slide your shovel down under the plant’s roots. The goal is to pop the bulbs, soil, roots, and all out of the ground with one shovel scoop. Then you can use a hose or your hands to remove the soil from around the bulb. Be sure to cut off any vegetation growing from the top of the bulb. This will leave you with a tuber or potato-like section of root. Store this root section in a cold but not freezing spot such as an unheated basement or garage. Place the tuber or bulb into a paper (not plastic) bag. The bulb should be kept just slightly moist but not wet. Plastic traps too much moisture and can encourage winter rotting or mold growth. Some gardeners pack their dahlias, glad, or begonia bulbs in crates of peat moss or sawdust for winter storage.

Protecting by Keeping the Winter Snow/Rain Out

If you don’t mind a bit of a gamble, you can simply cut the tops off of your tender bulbs, and then cover the soil with an oilcloth, a tarp, or an upside down plastic pot to keep out the winter moisture. In many parts of the country it is the winter wet that rots the bulbs not the freezing cold that kills them. This method of winter protection only works if the bulbs are planted below the frost depth of your soil. The deeper the bulb is planted, the more likely it will escape frozen soil.

Cannas, begonias, and dahlias planted in containers can be moved to a protected area such as a covered porch, covered, patio, under a table, or even the eaves of the house. Keeping the soil dry during the winter months may be enough to keep these summer bloomers alive.

Once spring arrives you can move the tender bulbs to a bright window inside the house and start them growing in fresh potting soil. If you decide to leave dahlias or cannas in the ground, you can remove the protective waterproof covering once all danger of frost has passed or when you see new shoots emerging from the ground in late spring.

Mulching to Protect From Frost Heave

Frost heave is when frozen soil forms cracks and breaks up into chunks. This action can actually heave normally hardy plants such as perennials and shrubs from the ground exposing their roots. Frost heave is most common in clay or poor draining soil. Improve the soil by adding compost and mulch around newly planted shrubs, trees, and perennials. Covering plants with evergreen pine, fir, or cedar boughs can also help prevent frost heave by keeping out moisture and raising the temp of the soil.

Protecting by Planting in Raised Beds

Cool air sinks. This is why gardens at the bottom of valleys and in low spots are slow to warm up in the spring. By gardening in raised beds you will be offering your plants added cold protection. Not only will the soil in raised beds drain more quickly to prevent ice crystals from forming, but the lower area around the raised bed will collect the coolest air with warmer air around the plants in the raised bed.

Protect by Adopting More House Plants

Your favorite tender plants may be able to spend the winters indoors as temporary houseplants. Tender succulents such as Echeverias, fancy leaved coleus, geraniums, and novelty patio plants such Abutilon or flowering maples can be induced to survive the winter if moved indoors or stored in a cold greenhouse. The goal during the winter months is to induce dormancy in the succulents and abutilon by keeping the soil dry and the room temperatures cool. When it comes to winter storage of coleus and geraniums, many gardeners enjoy these plants as houseplants in a bright window until early spring. Then cuttings are taken from the, now tall and spindly, plants, and new plants are rooted and planted in fresh potting soil; ready to go back in patio pots and planters in the spring.

Protecting by Investing in a Cold Frame or Greenhouse

Cold frames are ground level structures with a hinged glass top that can be used to store tender plants over the winter and also to grow winter vegetables. You can purchase readymade cold frames or build one of your own by recycling a used window to use as the protective covering. Investing in a home greenhouse can be as humble as ordering a plastic and metal frame that will fit against the house to protect potted plants or a free standing structure that can be heated for yearlong gardening.

However you chose to protect your plants this winter, you’ll benefit by preserving your favorite plants and looking forward to their return in the spring.