The cold weather is here! You might think that the gardening season is officially over, but there are important precautions that need to be taken before winter to help ensure your plants survive the cold winter months. Luckily, there are very simple and inexpensive methods of preparing your plants for winter.
1. Newly Planted/Shallow Rooted Plants
In cold winter months, cycles of the ground freezing and thawing can cause something called frost heave. As a result, the ground literally thrusts the plant out of the soil, which leaves the root system exposed to the harsh winter winds and temperatures. This can dry out the roots and ultimately kill the plant. Frost heaving is especially prevalent in plants with shallow root systems or plants that have been recently planted and not had time to adequately establish their root system. To help deter frost heave, you can try to finish planting in early fall so that plants have time to get their roots systems better established before winter. However, there are plants that will still be susceptible due to their shallow root systems. A few plants that are especially susceptible to frost heave include: strawberries, heuchera, scabiosa, leucanthemum, and gaillardia. To better protect plants like these, it is a good idea to mulch the plants after the first hard frost. The mulch will help insulate the ground and protect the root system. The insulating capabilities of mulch can help reduce changes in soil temperature during cycles of thawing and freezing. As an added precaution, not cutting back the plant can help insulate the crown and roots of the plant as well.
2. Tropical Plants
Whether they are in the ground or in a pot, tropical plants always need to be moved inside for the winter. When I say tropical plants, essentially what I mean is any plant that is not zoned for the region you live in. For the Midwest, this includes plants like: canna lilies, bromeliads, caladium, palms, elephant ears, and tropical hibiscus. Plants like these are popular in annual planters and can be treated as annuals, but with minimal winter care, you can extend their life more than just one year in your garden. These plants need to come inside your house of garage before the cold weather starts.
3. Potted Perennials/Shrubs
Any perennials that aren’t planted directly into the ground need winter protection, even if they are hardy in your area. When plants are planted directly into the ground, the soil insulates them and allows them to survive at lower temperatures. If you have planters containing perennials or shrubs zoned for your area, there are several options for preparing these plants for winter. If there is space, they can be simply put in your garage for the duration of winter. If this is not an option, you can put all your pots against a wall of your house or apartment balcony and cover them with straw as added insulation. If you choose this method, make sure your most cold hardy plants are on the outside of the grouping to help better insulate the less cold hardy plants. Another option you have is digging a hole and “planting” your plant pot and all. Doing this will allow the ground to insulate your plant throughout the winter. This is a suitable option if your potted plant has winter interest.
Strawberries start setting buds for their spring flowers in the fall, so a hard frost can kill the flower buds and significantly reduce the plant’s fruit production for the following year. The flower buds will die at any temperature below 15 degrees. If winter temperatures in your area normally fall below 15 degrees, winter protection is necessary for your strawberry plants. Mulching your strawberry plants can help insulate them and keep the buds safe from cold temperatures. You should mulch your plants with about 4” of a loose material like: straw, wood chips, shredded corn cobs, or pine needles. It might be necessary to add more as the mulch settles on your plant. It is a good idea to keep an eye on it throughout the winter to make sure it remains thoroughly covered at least 3” deep. You don’t want to mulch strawberries until the temperatures are consistently in the 20s during the day. If you mulch your strawberry plants too soon, the plant could fail to harden off. Another option you have for protecting strawberry plants is frost blankets. These are a great choice because they allow light to penetrate through to the plant, which helps more flower buds form while simultaneously protecting them from the cold temperatures.
Lavender plants usually survive in the Midwest, but winter protection can help them thrive and encourages healthy new growth in the spring. After the first frost, it is a good idea to cover your lavender plants with evergreen boughs. This shades the plant and prevents it from heating up during the day and creating extreme temperature changes between night and day. It also protects stems from drying out and dying back due to the cold winds. It should be noted that pruning should be done in spring after the first flush of new growth. If you prune lavender in the fall and cut into old wood, this promotes new growth that is very susceptible to winter damage. For this reason, pruning is done in the spring and lavender harvesting should cease in early September.
6. Butterfly Bush
Butterfly bushes are cold hardy, but in a lot of places in the Midwest, they die back to the ground every winter. Butterfly bushes can benefit from added winter protection. Before cold weather arrives, it is a good idea to prune stray branches. Butterfly bushes bloom on new wood, so there is not any risk of pruning off flower buds. Furthermore, a 3-4” layer of mulch should be applied to the base of the plant to help protect the root system. It is important when mulching shrubs and trees to leave a 1” space around the base of the trunk so the mulch is not touching the trunk. This helps prevent disease and applies to all shrubs and trees.
7. Crape Myrtle
Crape myrtle are another plant that are cold hardy in the Midwest, but tend to die back to the ground every year. This is heavily dependent on the micro climate the shrub is planted in within your yard. For example, a planting location in the center of a yard, or at the bottom of a hill would be more exposed to cold temperatures, and can cause the plant to suffer more winter damage. It is a good idea to think about winter protection before you even plant your crape myrtle. If you plant your crape myrtle against a south or west facing side of your house, the wall can serve as built-in winter protection for your shrub. If your tree is in an exposed area in your yard, it is a good idea to wrap it before especially cold winter days. The covering should go from the top branches of the shrub all the way to the base of the trunk. The covering needs to a be a breathable material like burlap. To hold it up without relying on the shrub for support, use three stakes around the shrub and wrap the burlap around the stakes as opposed to the shrub itself. This will give your crape myrtle added protection from harsh winter winds and cold temperatures.
Azalea are cold hardy and evergreen; however, they have delicate root systems making them very picky when it comes to the soil. Azaleas thrive in a loamy, well-drained topsoil that is slightly acidic and free of rocks and other obstructions. It is important to remember that a healthy plant has a better chance of winter survival, so take these soil factors into consideration when choosing a location to plant an azalea. For additional protection, spread 3-4” of mulch around the base of the azalea leaving space around the base of the trunk. If the temperature falls below 25 degrees, additional protection may be necessary. If the weather is expected to fall below 25, wrap your azalea bush in burlap fabric using stakes as described above for the crape myrtle.
9. Fruit Trees
Fruit trees will survive the winter as long as they are zoned for your region, but a few added winter precautions will help them thrive in the spring. Leaving space around the trunk, spread a 3-4” layer of mulch around the base of the tree to help protect the roots. Additionally, a tree guard should be applied to the trunk, especially if the tree is still young. A tree guard will help prevent trunk splitting and will deter wildlife like rabbits from nibbling on the bark.
For all your plants, remove the protective layer of mulch in spring when new growth begins to emerge. Remember to be careful when mulching around trees and shrubs and make sure you leave an inch of space between the base of the trunk. This helps prevent disease. If you keep all these tips in mind, winter protection is relatively simple. You can use a lot of the same techniques for many of your plants. If you have a plant you are concerned about that was not mentioned in this blog post, try mulching it. If it does better the following spring, continue providing winter protection. As long as you remember to remove it in the spring, it can’t hurt. What plants do you provide winter protection for in your yard? Let us know in the comments!