If you love gardening and growing fresh vegetables, you probably miss those vegetables in the winter. Did you know that if you plant the right crops, and care for them properly, you can harvest fresh vegetables long past your first fall frost? Keep reading for 7 of our season extension tips.
With some practice and the right techniques, in many parts of this country, you should be able to harvest vegetables almost year round. Even in cold northern climates, you can harvest late into the fall if the snowfall allows it. Plus there are still some vegetables like parsnips and spinach that will likely over winter to give you an early spring crop.
Using these same tools and techniques, you can extend your season both in the spring and in the fall. You might be surprised to find that some plants perform better than expected outside of what you might think of as their normal season.
Warm season vs. cool season crops
When we talk about vegetables and season extension, we need to understand that there are both warm season and cool season crops. Cool season crops will allow you to extend your growing season into the cold weather of fall and winter. These include plants like peas, broccoli, lettuce, spinach, turnips, kale, carrots, beets, etc. These are most anything that you would plant in the early spring. Some of these plants can take temperatures down to 10 degrees or below!
We can also extend the season for warm season crops such as tomatoes, peppers and eggplants. This can allow you to get a crop earlier than you normally would. It can also help you harvest your warm season crop later than you otherwise would be able to. This can be very advantageous for northern growers who have crops like tomatoes.
Planting crops for winter gardens
If you wish to season extend into the late fall and winter, plant cold season crops. In most areas you will need to plant these crops some time in mid to late summer. Many of these crops will hold long into the winter. However, they need to be mature size before it gets really cold. They will not do much growing in the very cold weather.
To determine when to plant, look at the seed packet for the ‘days to maturity’. Then check when your average first frost date is. Count backwards from your first frost date the number of days to maturity. Plant your cool crop seeds then.
A quick tip for southern growers. Shade cloth covering your winter garden area can help you to get your cool season crops started more easily. In many areas getting seeds to germinate and transplants to thrive in hot soil and high late summer temperatures may be one of the biggest winter gardening hurdles to overcome.
A quick tip for northern gardeners trying to extend their season earlier in the spring. Lay black plastic on the ground a couple weeks prior to planting. It will absorb the sun and help to heat up the soil faster.
One key to winter gardening is wind protection
Protecting your plants from wind damage is one of the most important aspects of season extension. It is not only low temperatures that kill plants. Desiccation can also kill a plant quickly.
When the soil/plant is frozen, the plant’s roots cannot take up water. However, the top of the plant is still capable of losing water. So if a harsh wind is drying out the top of the plant when the ground is frozen, the plant can sustain a lot of damage that it would not have realized from cold alone. Thus the simple act of blocking the wind can make a huge difference.
Now let’s get on to those tips!
Tip 1-Nature’s season extension gift
Wind protection can come in many forms. Sometimes you may have something as simple as a wall or fence that blocks your winter winds creating a warm microclimate behind it. If you have warm microclimates like a sheltered south wall, take advantage of it, and plant some of your winter vegetables there.
In addition to looking for microclimates in your yard, you can also use mulch to help protect your plants from cold weather. Fluffy things like leaves and straw make perfect mulch for protecting cold crops like root vegetables.
Mounding up leaves or straw over your vegetables before cold nights will protect them from the wind and cold temperatures. If you have crops like beets and carrots, a heavy layer of mulch can also help keep the soil from freezing around them. This will both protecting your crop, and allow you to easily harvest the roots later into the winter.
If you want to get more serious about season extension read on!
Tip 2-The Cadillac of season extension is a greenhouse
A heated greenhouse is the ultimate season extension dream that many gardeners have. Of course not every gardener can justify the expense to install and operate a greenhouse. And you don’t have to. Some home gardeners have a small ‘starter” greenhouse with minimal heat. This can be a good place to plant your fall crops without the cost of a large facility. Alternately you could use containers and a 3- season porch to extend your crop season.
If a greenhouse is not an option, don’t’ despair. There are plenty of other options to effectively extend your season for significantly less investment.
Tip 3-The high tunnel
The next best option is a high tunnel. A high tunnel is essentially just an unheated greenhouse. It is usually just a single layer of clear plastic over frames. No heat, no ventilation, many times not even doors. High tunnels are advantageous because they can be installed very inexpensively compared to a greenhouse but come with many similar benefits.
The frames can be installed in a permanent location, or you can install a temporary ‘caterpillar tunnel’. A huge plus for high tunnels is that you can stand up and walk/work inside them easily. An advantage high tunnels actually have over greenhouses is that you can remove the plastic covering in the summer months allowing you to utilize the space when it would otherwise be way to hot to grow inside it.
Inside a high tunnel, the night temperatures will not dip as low as outside. They will rise much higher during the day. Temperatures will rise much earlier in the morning and cool more slowly in the evening. As soon as the sun starts to come up up your high tunnel will be warm inside even on the coldest of winter days. Also, high tunnels will provide your plants excellent protection from wind damage.
Tip 4-Added benefits of an insulated high tunnel
We have found that our unheated high tunnel greenhouse will stay above freezing until the night time temperatures dip down below 20 degrees. Our high tunnel has an insulated cover on it and solid ends, so it provides more protection than a high tunnel with a single layer of plastic. Even without heat, it provides protection that is quite sufficient to extend the season. Rarely does anything except the most frost tender of plants sustain any damage even on the coldest nights of our winter. This insulated cover takes our high tunnel to the next level of protection.
An insulated cover of course comes with a significantly increased price tag. A viable, and very inexpensive alternative to spending thousands on an insulated cover such as Solawrap is to use 2 sheets of inflated plastic film. The inflated air layer creates a layer of insulation.
Whichever cover you choose to put over your high tunnel you can also utilize other frost protection strategies inside the high tunnel.
Tip 5-Low tunnels are very useful
If you do not have the space or desire to use large high tunnels, you can use low tunnels to do many of the same things. Low tunnels are just miniature high tunnels that sit directly over your crops. You can easily install a low tunnel over any crop in your garden. This can be done in a few minutes time.
Low tunnels are so useful, that many growers in more northern climates often use low tunnels inside high tunnels to add another layer of protection to their crops. Using a low tunnel with a heavy row cover inside a high tunnel can give you 5-10 degrees of extra frost protection beyond what the high tunnel is already providing.
It is worth investing in frames of an appropriate size to cover your crop to make low tunnels. It has been found that using a frame to support your frost protection works better than using a ‘floating row cover’ that is just loosely draped over the plants. You don’t want the frost protection touching the leaves of your plants. If it does the part of the plant touching the row cover is more likely to get frost damaged.
Select the appropriate cover for your low tunnels
There are a few different options when you are considering covers for your low tunnels. You can use sheet plastic, or you can use a frost protection row cover cloth. For maximum frost protection, you may wish to combine two together.
Plastic will trap more heat and get warmer during the day than a fabric cover will. It will not allow rain through keeping your crop dryer, but may require you to water it mid winter. A downside to plastic is that if you have a very warm day (like 50 degrees) you will probably need to open your low tunnel during the day to allow some of the heat to vent.
Conversely, a thick cloth row cover cloth will provide more frost protection than plastic will. It will also allow water and wind through, so it will not protect your plants from wind desiccation, nor will it allow you to control the amount of water the plants are receiving.
As you might imagine under many circumstances a combination of the two may prove the best option. A fabric row cover that you can add plastic over as the temperatures drop will provide you the most versatile frost protection. If you live in the south where day time temperatures mid winter are often 50 degrees, you may wish to avoid using plastic. However, if you live in a more northern climate, you will definitely want to use both plastic and a fabric cover to maximize both your night time frost protection, and also your daytime growing temperatures.
Tip 6-Cold frames are similar to low tunnels
If you wish to have something a little more permanent than a low tunnel, you can use cold frames. They are often constructed using recycled materials. Cold frames are simply a box with a clear roof angled to face the south. Often times they are wooden boxes with old windows set over the top as a roof. They can also be made out of straw bales. They can be constructed as simply or elaborately as you choose.
The drawback is that they are not as easy to store or move as a low tunnel. Working with old windows can also be a safety liability due to the possibility of broken glass. If you make cold frames using old windows, please be sure to secure the windows thoroughly so that they do not get damaged by the wind.
One last tip…Tip 7-Recycle Christmas decorations
Yes, Christmas lights can be used for season extension. So, search your attic and garage and recycle those Christmas lights. Now, when we say Christmas lights we are not referring to LED ones, but rather the incandescent ones that give off heat.
Insert short stakes inside the low tunnel and run a string of Christmas lights above your plants between the stakes. Be careful! Do not allow the lights to touch the plants or the low tunnel cover. The low tunnel will trap quite a lot of heat from the lights inside it.
This is particularly true if you have both plastic and a heavy frost protection row cover over your crop. A temporary heat source such as this can be very useful if you have a couple unusually cold nights followed by more normal warmer weather. For example, a late frost after setting out your tomato plants. However it can also be just enough heat mid winter to prevent getting frost damage on cold crops as well.
We hope that no matter your climate, this gives you some inspiration to try winter gardening this fall! Next time we are going to discuss some of our favorite cold season crops, and just how cold hardy they actually are.
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