There is a season for everything. In life, as with gardens, we know this vividly and yet how often we try to defy the odds and accelerate the beginning of the gardening season, or attempt to push the limits on the back end. Yes, gardeners are some of the most tenacious people I know and I love that about us!
Other than some blind luck, there are some easy to apply techniques that make extending the season a more predictable opportunity for success. To begin, these techniques can apply to annuals, vegetables, herbs and even shrubs. You’ll just need to adapt these suggestions to the plants you are trying to protect.
An easy place to start if you know that you will be pushing the limits on the growing season is to look for varieties that are considered “cold hardy”. Simply planting annuals or vegetables that have a higher tolerance to colder temperatures than some of their less hardy cousins may be all that is required to buy some extra time for your plants. This will require a small amount of research before you head to the garden center, but most seed companies list this information routinely in catalogues and online.
Another technique I often use includes applying a thick layer of organic mulch around the base of all my plants. Not only does it keep the roots warmer, it also helps to maintain the soil temperatures at a more even level and can reduce the chances of the ground freezing or heaving. In some cases, as with spinach or strawberries, I’ll cover the entire plant in a layer of mulch to add an additional barrier of protection for the roots and foliage.
Physical barriers are another effective way to retain and capture a few extra degrees of heat while keeping season-ending frost off of the plants. Commonly referred to as floating row covers, the material is typically made of a lightweight spunbound or nylon material. In some cases, the material is so light that it can actually be laid directly on the plants, so it appears to float. In virtually all cases, I prefer to support my row cover with metal wire or PVC pipes stuck into the garden beds. The row cover material is placed over the frame supports, a few inches to a foot above the plants. It is then pulled tightly and secured around all the edges with bricks, soil or whatever you may have that is convenient and sturdy enough to hold.
The row cover material is designed to allow light, water and air in but provide a protective barrier from frost and pests. When the sides are secured around the bed completely, several extra degrees of warmth can be retained and could make the difference in survival for marginally hardy plants.
On the subject of insulation, blankets, plastic, buckets and the like can all serve to add critical protection on frosty nights. The two most important matters to consider are to be sure the covering protects the foliage by keeping frost off and that it extends all the way to the ground. This last step is very important because it ensures that warmth from the soil is trapped – an essential component in attempting to protect your plants by adding a few extra degrees under cover.
I’ve seen many commercial remedies for this problem as well as countless homemade versions of the same. However, with the exception of row covers, whenever an enclosure is placed over your plant(s) at night, be sure to remove it the next morning or at least provide a way for the heat to escape. Otherwise, efforts to save your plants may backfire once the sun comes out. That same insulating barrier that kept your plants warm and protected at night may be the very thing that cooks your plants the next day, especially with plastic. Direct sunlight and a covered plant can make for a deadly combination if you’re not careful. Even on a cold day.
When time and energy permit, container-grown plants offer the maximum in portability in allowing you to maneuver plants away from “Jack Frost”. Having the ability to move plants from the frigid outdoors to a protected shelter and back again can buy you several weeks or more of extended growing time.
Another trick I often use is to look for the most protected, yet sunny area for planting annuals, vegetables and shrubs. Referred to as “microclimates” because of their small, unique growing environment, in this example, these are areas protected from wind, driving rain, frost or snow. This mini environment can potentially allow plants to survive outdoors when otherwise they might easily succumb to a killing frost or other harsh conditions. Microclimates provide not only protection from the elements, but when planted near a brick or stone wall, for example, heat absorbed and retained during the day is released at night and plants in close proximity will benefit from this exchange.
Cold frames are another technique for providing additional protection in the fall. Think of a cold frame as a mini greenhouse. The basic premise is a solid, insulating barrier around the plants and a glass or plastic top that allows sunlight and heat in. However, all cold frames should provide a way for heat to escape during the day. Cold frames can be constructed from wood, cinder blocks, hay bales and more.
You can plant directly into the soil within the cold frame or place seed flats or containers inside. A sufficiently insulated cold frame can temporarily extend the growing season and it can even provide an environment warm enough to allow tender plants to thrive all the way until spring.
In many parts of the country, simply planting into soil protected by black plastic will suffice at providing the growing environment plant roots need to remain viable and productive as temperatures drop. As a covered surface, black plastic is most effective at trapping and retaining heat. It is readily available in home improvement centers. It’s inexpensive, easy to install and remove at the end of the growing season.
There is a season for everything, but it doesn’t mean you have to stop gardening just because temperatures fall. Extending the season is an exciting and rewarding endeavor made easier by knowing a few easy-to-apply techniques mentioned above and it gives you even more time to hone your skills come next spring.