Growing a food garden is a rewarding experience that can provide fresh, healthy produce throughout the year. However, depending on where you live, the growing season can be limited, and it can be challenging to extend it. Season extension techniques can help you extend the growing season in a food garden with raised beds.

Protection from unexpected extreme temperatures

Raised beds have become increasingly popular in recent years due to their many benefits, such as better drainage, improved soil quality, and easier access for gardeners. They are also well-suited for season extension because they can be easily covered and protected from the elements.

What we used to know is no longer valid because of climate change. Nobody really knows how to predict vegetables from high and low temperatures during a growing season. The Deep Roots team like to be conservative about when to plant to make growing easier for beginners. But use also want you to have the tools to be ready for unexpected cold temperatures and heat waves.

Our blog post Planting Calendar for Climate Zone 5b provides guidelines on planting dates and more. We don’t have a planting calendar for climate zone 6a which is somewhat warmer and applies to most of the city of Chicago due to the “lake effect.” Lake Michigan influences the climate of Chicago and most of northeastern Illinois. The large thermal mass of the lake tends to moderate temperatures, causing cooler summers and warmer winters.

We encourage experienced Chicago gardeners to take advantage of the longer frost-free growing season in climate zone 6a in most neighborhoods. But monitor night temperatures carefully. Be prepared to protect seedlings. Adjust our zone 5a planting calendar dates. The zone 6a spring planting dates are 2 weeks earlier and the fall planting dates are 2 weeks later than zone 5b. 

Covering the beds

Let’s explore the different techniques for extending the growing season in a raised bed garden that are also needed to protect plants during unexpected high and low temperatures.

• Local climates vary in the same climate zone. The length of the growing season and the average temperature during that time will determine what can be grown and when. Other factors to consider include the amount of sunlight and wind exposure.

• Know the temperature tolerances of your food plants. View the temperature tolerances for the veggies we include in our Planting Calendar Zone 5b blog post. 

• Raised beds are well-suited for season extension because they can be easily covered and protected from the elements in several ways. Materials, include row covers, cold frames, hoop houses, and greenhouse tunnels. These covers help to trap heat, protect the plants from wind and cold temperatures, and keep pests and diseases at bay.

• Floating row covers are lightweight fabrics that can be draped over the beds and secured with stakes or pins. Medium gauge fabric is fine. Easiest support is half inch PVC plastic pipe bent or metal wire bent into hoops with the ends buried in the soil. 

• Floating row cover allow sunlight, water, and air to pass through but create a microclimate that is several degrees warmer than the surrounding air. They are excellent for protecting crops from frost and pests, but they need to be removed periodically to allow for pollination.

• Cold frames are simple structures made from a wooden frame and a clear plastic or glass top. They capture and store solar energy during the day and release it at night. They are ideal for early spring and late fall crops. They can be easily built or purchased.

• Hoop houses or temporary hoop structure are similar to cold frames but larger and more permanent. They consist of a series of metal hoops covered with a clear plastic sheet. They can be used through the winter in mild climates.

• Greenhouse tunnels are larger structures that provide even more protection than hoop houses. They are typically made from PVC pipes and covered with a heavy-duty greenhouse plastic. They are best suited for year-round growing in colder climates.

• Shade protection. Provide shade during heat waves for tomatoes, peppers, tomatillos, eggplants. There are different grades of shade cloth for hotter months. Place the shade cloth above your plants with a support and clips. Or place the shade cloth over hoops attached to the your bed. After a heat wave some tomato varieties stop producing fruit for while and other varieties stop producing for the rest of the season.

Starting seeds early

Seed starting indoors under grow lights. Explore the many ways to grow seedlings (also called “transplants”) from seed indoors. But most important is to use as your growing medium a mixture of half Deep Roots compost (or a similar compost) and half top quality worm castings made from composted manure. Remember to give the seedlings full sun for 8 hours or more. This usually requires a grow light placed correctly near the top of the growing plant. Usually the sunlight from a window is not adequate.

Remember that some crops must be planted only from seeds like amaranth, spinach and root crops (radishes, beets, carrots, parsnips, turnips, garlic, onions). Root crops usually won’t survive if their roots are disturbed. See more details is our blog post Seeds and Seedlings: Beginners… 

Winter sowing is a germination method taught by Trudi Davidoff that starts seeds outdoors in an enclosed container in winter. It’s basically a cold frame that just uses plastic gallon milk jug (or a similar container) instead of a wooden frame. If you are interested in other germination methods like inside sowing or direct sowing, consider trying winter sowing instead. Learn all the details on the winter sowing Facebook page – search engine, group photos, files created by members. A great resource of experiential information open to the public. The group takes pride in being an educational, family-friendly, international member forum! They love helping beginners learn Winter Sowing with advice kindly given. Find additional winter sowing information at Gardening Know How:

Plant Selection

Another way to extend the growing season in a raised bed garden is by choosing the right plants. Some plants are more cold-tolerant than others and can withstand lower temperatures and shorter growing seasons. These include leafy greens like spinach, kale, and lettuce, as well as root crops like carrots, turnips, and beets.

Other plants, like tomatoes, peppers, and eggplants, require warmer temperatures and a longer growing season. These can be grown in a raised bed garden, but they may need to be started indoors early in the season and transplanted outside once the weather warms up.

It's also important to choose varieties that are well-suited for the local climate. Many seed catalogs offer cold-hardy varieties that are specifically bred for cooler temperatures and shorter growing seasons.

“Grow Your Own Food” blog posts

See the full list of our Grow Your Own Food blog posts. Each post is assigned ”tags” which are under the post title. If you need a quick answer to a gardening question give us a call or send a text to our customer support team – support[at]deep-roots-project.org AND 708-655-5299.

Deep Roots online store

See our online store for details about prices, ordering and delivery of raised beds, planter boxes, microbe-rich compost, worm castings, leaf mulch and more. We don’t sell traditional soil, since we use 100% compost as our growing medium. Our online store has 2 sections – (1) raised beds and planter boxes and (2) compost, worm castings, fertilizer.

Please contact our customer support team before placing an order online so we can assist you with the details and answer your gardening questions. You can pay by credit card in the store or by check.

(708) 655-5299 and support[at]deep-roots-project.org

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