Protecting Your Plants From Frost

    Photo: Gabriel Anast/FlickrWith November rapidly galloping towards a close, the nights are starting to get very, very chilly in many corners of the US. In some regions, frost is already on the ground, while in others, it's going to happen any day now...and there are few things more tragic than walking out onto the porch in the morning only to realize that all your plants were hammered overnight by an unexpected cold snap.

    It's time to get your garden frost-ready, if you haven't already, so that you can preserve your fragile plants, young trees and shrubs, and delicate flowers.

    What needs frost protection?

    Any time you select something for the garden, you should take note of the optimal growing zone and whether it's frost tolerant. Some plants may need to be brought indoors at night or full time during the winter to protect them from harsh weather, while others may just need covering. Others need some support in their first few years of life -- young trees and shrubs usually benefit from frost protection for the first two to three years. All your plants should be considered for frost protection if the weather is going to be unusually cold.

    Container plants need special care because their roots don't have soil around them to help insulate them from the cold. Likewise, anything planted in an exposed area of the yard should be given particular attention.

    When do you need it?

    Frost protection at night is a must when the forecast dips close to freezing. Make sure to put your frost protection measures in place before dusk so you can capture the last warmth of the day. You may need insulation for your plants during the day if temperatures are at or below freezing, and if you live in a climate that cold, hopefully you're taking additional steps like mulching well to protect vulnerable roots from freezing.

    Think ahead: install stakes around fragile plants that will need protection so you can quickly wrap them when the forecast calls for it. The stakes help you create a little tent, allowing air to act as an insulator to keep the plant warm. Put large container plants on casters so they're easy to move around as needed, and consider wrapping the containers for the duration of the winter if you have to leave them outside.

    What kind of frost protection do you need?

    At the most basic, you can toss a sheet over susceptible plants when the forecast says it's going to be cold. You can also purchase specialized frost cloth, which is designed to protect plants. It wicks away moisture to prevent the formation of ice on their leaves, and has a layered construction to provide more insulation.

    Some gardeners also find it helpful to install a jug partially filled with water under their frost cloths and near their plants. During the day, the jug absorbs heat, and at night, it radiates warmth to keep the plants above freezing.

    For more robust protection, you need glass cold frames. You can use old windows and other scrap glass to make cold frames if you don't want to purchase them new from the store, but in all cases, the goal is to essentially create a miniature greenhouse. A handyman can help you design and install cold frames if you're not feeling confident about this DIY project. Cold frames can be left in place during the day, too, though you should make sure they don't get too warm, as you don't want to cook your plants or shock them with temperature extremes.

    Very delicate plants need to be moved to a greenhouse or inside your house during the cold season. Such plants should be clearly marked when you buy them to indicate that they are not frost tolerant.

    What should I do if my plants were caught without protection?

    Even the most diligent gardener can get caught out -- an incorrect forecast, a busy night, or a variety of other things can lead to some plants not getting the protection they need. Depending on the severity of the frost, they may be able to recover. On the low end of the scale, some robust plants can take a night of cold.

    On the intermediate level, you may need to let the day fully warm and determine whether any parts of a plant have been killed off by frost. Do not trim away dead material, as it can actually act as insulation for the rest of the plant and it can be hard to determine which parts of the plant are truly dead. Furthermore, pruning can stimulate plants to grow, which is not desired -- the new growth will simply become frostbitten immediately because it's so tender. Instead, plan on pruning in spring. In other cases, plants may have been too fragile to handle the weather, and you'll have to give them an honorable funeral in the compost.

    Don't confuse winter bronzing and leaf loss with frost damage. Some plants deal with extreme temperatures by going into hibernation mode. Deciduous trees and shrubs drop their leaves, and some do so quite late. Evergreens may bronze, turning orange to brown in the winter. They're not actually dying, although they don't always look very nice, and they will turn green again next spring!

    Your garden might not always look totally presentable in the winter, between frost cloths, bronzed evergreens, and cold frames scattered about to protect more tender plants, but the important thing is survival. If you're new to an area, it's worth consulting a local landscaper or nursery staff person to talk about which plants are hardiest and what to expect during the winter months.

    Katie Marks writes for

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