The warmer temperatures of October have come and gone, but autumn in Colorado often extends into November. For avid gardeners, that’s a bonus.
You can still garden well past that. Days may still reach into the 50s and 60s, warming the soil enough to make it possible to stretch the gardening season. While the typical gardening months in the metro area run from May through September, cultivating a few cool-weather crops, including herbs, is possible — with a little help.
Days may still reach into the 70s and 80s, warming the soil enough to make it possible to stretch the gardening season well into fall. While the typical gardening months in the metro area run from May through September, cultivating a few cool-weather crops, including herbs, is possible — with a little help — as we head into the next few months.
The ideal place to locate a cold frame is near a south or west facing brick wall or wooden fence for maximum solar heat absorption. (Getty Images)
Denver’s high-altitude location is not conducive to cultivating crops that might be exposed to freezing temperatures in the fall, but you can trap some of the beneficial heat from sunlight to keep growing greens and a few hearty vegetables. Crops that actually thrive in cooler temperatures and can be grown into fall, if protected from frost, include lettuce, chard, kale, collards, spinach, arugula, endive, beet greens, scallions, leeks, carrots and radishes.
In addition, a sizeable number of common culinary herbs that have been growing outside can also be divided, with portions brought in from the garden, to spend the colder months on a sunny windowsill.
There are a few easy methods to keep winter at bay. Some of the more popular ways include the use of floating row covers, cold frames and mini greenhouses. These outdoor structures are relatively easy to construct, with kits available at area garden centers and big box stores. There is also a wide selection of supplies online.
Keep in mind that plants growing in outdoor structures during the fall months may need additional heating as the weather gets colder. Portable greenhouse heaters are also available online.
Floating row covers
When using row covers, consider mulching plant root zones with grass clippings or ground up autumn leaves for additional moisture and heat retention. (Getty Images)
Row covers are made from lightweight spun polyester fabric that protects crops and allows light to penetrate. They come in various weights, lengths and widths and can be supported by a series of hoops or can be placed directly on the growing plants. Depending on the weight of the fabric, they can provide 2 to 8 degrees of protection against cold temperatures and frost.
When using row covers, consider mulching plant root zones with grass clippings or ground up autumn leaves for additional moisture and heat retention. Don’t forget to water regularly.
Cold frames
The purpose of a cold frame is to extend the growing season well into the fall and/or to start seeds on a smaller scale in the spring. This is achieved by controlling the growing conditions, without the expense or the work of building a greenhouse. The ideal place to locate a cold frame is near a south or west facing brick wall or wooden fence for maximum solar heat absorption. Crops can be planted in amended soil directly in the ground or in pots above ground.
Cold frames are also ideal for additional jobs such as forcing bulbs at holiday time to bring inside when ready to bloom, and for hardening off plants before moving them to the garden in the spring. Cold frames are relatively easy to build or easy to assemble from kits.
Mini greenhouses
Similar to a cold frame, a mini greenhouse is simply a larger version. They come in a wide variety of shapes and sizes. Use them to prolong the gardening season or for starting crops in the spring for later planting in the garden. They provide more space for pots and flats of plants than a cold frame. If purchasing a mini greenhouse, consider models that have flaps that can be opened or closed, depending on temperature and air circulation needs.
Growing herbs indoors
Common herbs well suited for growing indoors include basil, chives, cilantro, parsley, rosemary, mint, oregano, thyme and sage. (Getty Images)
Bring the outdoors inside and enhance your favorite dish with fresh herbs grown in a windowsill garden. Locate it in a south or southwest window for maximum sun exposure. Common herbs well suited for growing indoors include basil, chives, cilantro, parsley, rosemary, mint, oregano, thyme and sage.
Several herbs won’t survive winter temperatures outdoors, so transfer the whole plant to a pot and return it to the garden in spring. These include basil, rosemary and cilantro.
Divide plants by gently digging up the entire root ball, slicing it in half with a sharp knife, and returning a portion to the ground to be replanted if desired. Water well. Herbs that are destined for indoor pots should be watered when transplanted to minimize the initial shock.
Care for herbs much like you would care for a houseplant. They need about 6 to 8 hours of direct sunlight to thrive. Indoor conditions tend to be dry during the winter, so placing pots on top of saucers with pea gravel that is kept moist on a regular basis increases needed humidity and prevents leaves from desiccating. Rotate each pot often so light distribution is even. If plants begin to get leggy or lanky in lower light conditions, it may be necessary to supplement with LED grow lights, also widely available.
You don’t have to wait until next spring to enjoy the reward of growing delicious edible plants for a few additional months. Stretch the gardening season and enjoy fresh harvested greens, vegetables and herbs well into the cooler weather.
Judy Kunz is a Colorado master gardener.
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