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Simple ways to extend your growing seasonThere is nothing like the taste of freshly picked produce: peas, carrots, tomatoes etc. All taste amazing when you grow them yourself, and pick them fresh from the garden.
However, the majority of locations in the United States have a short growing season. Just when your tomatoes, peppers, and squash are ripening, along comes an early frost, and you can say goodbye to the garden. In the spring, when the freshly planted potato shoots are getting their first leaves, and the tomatoes are establishing themselves, a late frost can decimate everything in your garden and you have to start again.
We can show you there are simple ways to extend the growing season both spring and fall. Ultimately we finish with an answer we ourselves have tried and tested successfully over 25 years.
We hope you enjoy and benefit from these suggestions of how to extend your growing season.
Udgar ParsonsFounder of Growing Spaces
www.geodesic-greenhouse-kits.com
Climate and WeatherOne of the most important things to take into consideration when deciding how to extend your growing season is climate and weather. To understand climate is to know the average range of temperatures in your location. Weather is the daily unfoldment of all the different components of the factors that affect your growing of desired crops.
As you may be aware the U.S. has been conveniently divided into numeric climate hardiness zones that tell you a range (within 10 degrees Fahrenheit) of average high and low temperatures. It is really easy to figure out what zone you are in. Simply go to this website and type in your zip code. Knowing average climatic conditions is essential when determining when to sow seeds, transplant and harvest your crops.
Climatic change is definitely going on and many areas are becoming warmer and drier while others are becoming wetter and cooler. This can affect your gardening decisions drastically. It would be helpful to research data to identify climate changes in your area. Here is a map identifying changes by hardiness zone from 1990 to 2006.
Since there are many microclimates within these broad zones, it is very helpful to be aware of the advantages and disadvantages of your particular microclimate. As a general rule, temperatures drop about 3.5 degrees per every 1,000 feet in elevation gain, so higher elevations are commonly cooler later in the spring and earlier in the fall.
TopographyTopography is one of the biggest variables that affects your garden, and the main reason for the existence of microclimates. It is very important to understand how topographic features influence growth potential in your area and on your particular piece of property. An example of this is how cold air flows down at night and settles in valley floors. The hilltops surrounding the valleys are considerably warmer. I personally live in a valley and in the winter on a cold night my friends who live on higher ground consistently report 5°–8° Fahrenheit warmer nighttime temperatures.
Local vegetation such as trees and bushes can block and disperse cooler breezes keeping a garden warmer, which helps crops grow longer and better. Exposure to wind can be a serious hazard, especially in the spring when trying to germinate and protect young seedlings. Some simple wind protection measures will be outlined in the technologies section.
If you have a south facing masonry wall somewhere on your property, you will notice that on sunny days this warms up and the warmth lasts into the night, giving plants nearby an extended growing season compared to other plants not near the wall.
Taking advantage of and strategically creating warm microclimates can be a useful season-extension technique. When choosing planting spots outdoors, consider shade from nearby trees or structures, wind protection, and sun exposure of the specific planting area. Places near brick, rock, homes, fences and areas with good southern exposure generally absorb and retain heat from the sun, creating a warmer environment for your plants.
Here’s an excellent website with lots of suggestions on creating microclimates.
WeatherWeather consists of temperature variations, cloud cover, wind, precipitation, frost or lack thereof. You as the gardener have to keep a constant eye on the weather and understand the common weather patterns experienced in your area. An example of a weather pattern is here in the Rocky Mountains, where we will often get a warm front with rain and clouds passing through. This warm front is usually followed by a cold front with clear skies and rapidly falling temperatures. If this happens during the night it is very common to experience below freezing temperatures during the coldest time of year. This would be an ideal time to apply whatever crop protection methods you have available.
As a gardener trying to grow as many days of the year as possible, it is vital to keep a close track on the weather patterns as they unfold throughout the day and night.
Garden Design and Planting DecisionsIt is very useful to know the temperature requirements of the plants you are growing when designing your garden. Some plants prefer cooler shady conditions while others do well in full sun.
Growing taller plants to the south provides shade for the plants north of them; examples of these taller plants are sunflowers, Jerusalem artichokes, tomatoes, climbing beans, corn, peppers, and many others. I’ve used Jerusalem artichokes as a very effective windbreak planted on the west side to guard from drying winds in the spring.
Raised beds give an opportunity for soil to warm up earlier in the spring, and the presence of a pond in your garden can help stabilize temperatures of plants close by. The use of trellises can not only provide beauty for your garden, but also give extra growing space and provide shade for plants that may need it.
Choice of Seeds It has been shown that seeds from a nursery with a similar climate to yours often perform better than seeds produced in a different climate; it is very useful to know the location of your seed source nursery.
It is vital to read and follow the instructions on the seed packet, especially when you’re learning how to garden. The seed packets give instructions on ideal germination temperatures as well as how deep and far apart to sow the seeds. You can also learn about how to thin and transplant each variety from many seed packets.
If you choose to save your own seeds, choose seeds from stronger producing plants that will create offspring that do well in the climate you have. Seed saving is very easy and enjoyable and typically one plant produces far more seeds than you can ever use, so you can share them with your friends.
Take care when saving seeds from similar families of plants, i.e. Brassicas like cauliflower and broccoli, as there is a risk of cross pollination producing a mixed variety of offspring. Even melon and cucumber can cross pollinate producing a rather unpleasant tasting melon.
Soil and CompostDense and compacted clay soil can not only be very slow to warm up in the spring, but can also make watering problematic. Compacted soil can stay moist and wet, which prevents air from getting to the roots, or it can stay very dry due to the inability of moisture to penetrate the soil when you water.
Sandy soil however can drain far too quickly, creating too dry of an environment for optimal growth. The addition of organic matter to both soil types can help immensely. It is very important to know your soil type and amend accordingly. This is a vast subject in and of itself and merits a decent amount of study.
Composting of vegetation can be tricky depending on the climate present in your location, but it is well worth taking the trouble to learn about composting. Not only is it a wonderful use of all your excess vegetation (which you are bound to have), but it is a vital means of replenishing your soil on a regular basis. In most regions of the U.S. it is important to attempt to keep the compost warm through the winter and moist enough in the summer. Again it is a topic that will repay study. The Compost Guy has a down to earth approach.
Plant ChoicesOne of the most important things to consider when planning a garden is plant selection. When you choose the right plant to put in the right place, chances of successful production increase greatly. A short growing season and cool nights means that, generally in an outdoor garden, it doesn’t stay warm enough for a long enough time to support coveted warm-season crops like cucumbers, peppers, beans and tomatoes. Instead, cool-season vegetables, including leafy greens and root crops, are more productive and easier to grow.
When looking for vegetables and varieties to try in the outdoor garden, select those that thrive in cooler climates and mature to harvest in fewer days. Keep in mind that even short-season plants will need extra days to mature in cool, high altitude climates. When selecting annual vegetables and herbs, focus on varieties that require fewer days to mature and also those that are frost tolerant. If you are selecting perennials, look for those that are winter hardy as they will live through the winter and regrow the following season.
Plant Protection: Season Extenders“Season extender” is a general term used to refer to any technique or product that protects plants from untimely frosts. Untimely frosts are generally radiation frosts that occur on clear nights in the absence of insulating cloud cover. Radiation frosts generally occur in the spring and fall and only bring temperatures down a few degrees below freezing levels, making it worthwhile to protect your garden. Season-extension products and techniques may also hasten plant growth by trapping heat, providing a warmer environment for continued plant growth.
Floating Row CoversThese can be blankets, tarps, floating row cover or frost cloths, and are very useful weapons in your fight against frost, drying winds and hail. If they are light in color and opaque some people leave them in place, but it is important to make sure the plants are not deprived of the light they need. Most people simply put them over the garden bed as needed to protect against some of the elements mentioned. Wire hoops over the rows of low growing plants can make it easier to get the row covers on and off. Some people drape them around their tomato cages to help protect tomatoes against frost or other environmental challenges. Typically they give an extra 3°–6°F of protection.
Mulch and StrawThe use of mulch, of which straw is a type, can benefit in two ways: in the fall it slows down the rate of soil cooling thus extending the growing season, whereas in the spring and summer it prevents the soil from drying out as rapidly. If you use hay, make sure it does not contain weed seeds. The downside of mulch is that it can encourage moisture loving pests such as pill bugs.
Wall of WaterThis technology can be very useful when protecting individual frost sensitive plants in the spring, such as tomatoes and peppers. These are generally fast-growing plants however, and soon outgrow the protection, so the use of these products is limited. They generally have a short lifespan when exposed to UV radiation. Read more here.
STRUCTURESLow TunnelsCreating a low tunnel with a frame over the garden is another way to both keep the cold out and hold warmth in. A low tunnel frame covered with clear agricultural plastic or row cover can also be used to protect plants from cooling wind and deter hungry herbivores.
The low, spread-out shape of low tunnel covers makes them ideal for trapping radiant heat from soil, although the ends and side of these covers should be opened during the day to prevent overheating. On warm days, it is best to entirely remove the cover from its frame, whereas on cool days and warm nights the cover may be only cracked open. A low tunnel should be closed on cold nights and can remain closed on cloudy days.
If managed properly, a low tunnel may provide 3°–6°F of frost protection, and works well for cool-season crops that can tolerate light frosts. This technique may add between two and six weeks to the growing season in the fall or spring.
Low tunnels become even more effective if another heat source or insulator is added to them, such as a space blanket, string of C-7 holiday lights, or even a small heater. There are lots of good descriptions available online.
Cold FramesThese can be a very simple way of protecting your starts in the spring, but once the heat of the summer comes you risk baking your plants. Cold frames can be very labor-intensive because of the work involved in monitoring and regulating temperatures. For this reason we recommend that you place cold frames close to your house where you can check on them often. If you can devise a way of automatically opening and closing the lid to prevent your plants from overheating, that would be the best option. Cold frames can range from very simple structures that are made of scrap or used materials to very complex works of art made of high tech materials.
High TunnelsHigh tunnels, as well as greenhouse structures, provide greater air insulation and are the most sophisticated methods of season extension. Both structures allow a gardener to start earlier in the spring, extend the season further into the fall, and even allow for growth of plants that typically don’t grow well in cold climates. These useful structures provide winter protection and trap heat, but need to be managed for cooling during the summer months and on warm days. The disadvantage of high tunnels is that they can be challenged by high wind or heavy snow loads. Here is the go-to resource for High Tunnels.
GreenhousesThe original design for greenhouses was developed in the U.K., which has a completely different climate from the U.S. They are usually just season extenders but certainly stronger and more wind friendly than high tunnels. There are many different types of greenhouses, but most of them have the same features. They usually get too hot in the summer, and too cold in the winter for optimal plant growth. Because of the lack of insulation, people have found it costs a lot to heat them during the winter and cool them in the summer.
People usually have potting benches or shelves inside the greenhouse, which is certainly useful to be able to garden at waist height. The problem with this arrangement is that the plants tend to dry out more quickly and experience more temperature extremes than when planted in the garden bed. A good selection of typical greenhouses can be found here.
Growing DomesThe Growing Dome is a huge advance in the world of greenhouses. It is truly a way of extending your growing season year round.
Back in the mid-80s various research establishments were trying to find a way to improve the efficiency of greenhouses.
At the Windstar foundation, founded by John Denver, in Aspen, Colorado, a research team, along with design input from Buckminster Fuller, built a geodesic dome greenhouse, which could grow produce year-round in the harsh climate of the Rocky Mountains using no extra heat input from outside sources. The structure was called a Biodome, and, using the principles of passive solar design, it was able to maintain an interior temperature 50° higher than the outside ambient temperature, with no extra heating.
Based on this research, Growing Spaces has been building the energy efficient Growing Dome greenhouse since 1989. The built-in passive solar design features enable the Growing Dome to capture and store the heat of the sun in the day using an aboveground pond and a central air system. Heat loss at night is significantly slowed down by the use of four unique insulating methods.
In the climate of the Rocky Mountains, the Growing Dome is often able to maintain nighttime temperatures approximately 30° warmer than the outside temperature with no extra heat input. It also has automatic cooling features that enable it to grow throughout the summer with little or no cost for cooling.
Rather than having shelves and benches, the unique design of the Growing Dome enables the owner to create an enclosed indoor garden with growing beds and pathways. For a fuller picture of how the Growing Dome is able to do this, download our free E-book: “9 Reasons a Growing Dome is Better than a Greenhouse”.
We at Growing Spaces are happy to support your gardening efforts in any way we can. We hope you’ll enjoy our upcoming E-book: “Enhance your lifestyle with indoor gardening”.
Udgar Parsons, Founder of Growing Spaces
