While heat is the biggest challenge when planting your fall garden, by the end of fall there is the challenge of cold weather. In an average year, the first light frost will usually occur in mid- to late October, although sometimes the first frost occurs sometime in November. A light frost, where the low temperature dips down to 30-32 degrees will not damage fall vegetables. The cold may even improve the color and flavor of the vegetables. Most fall vegetables will tolerate temperatures down to 28 degrees without significant damage. In fact, allowing exposure to below-freezing temperatures will often allow the plants to better adapt to the cold, increasing their hardiness to later cold weather.
On a cold morning before the temperature is back above freezing, your plants may look wilted and permanently damaged. However, by the time the temperature is back above 32 degrees, they will recover and continue growing. It is important not to harvest these fall vegetables until the temperatures are back above 32 degrees and the plants have naturally recovered from the frost.
When low temperatures dip below the mid-to upper 20s, it will be necessary to protect semi-hardy fall vegetables with a light row cover to minimize damage on those vegetables. Some particularly hardy vegetables, such as spinach and kale, will not need extra protection until the low temperature is near 20 degrees.
It is usually best to remove the row covers during the day to allow the sun to warm the soil more efficiently when we are still getting intermittent frosts. As we get later into the year, leaving the row covers on may help create a mini “greenhouse effect” and prolong your growing season once we are regularly dipping into the 20s overnight.
See Part 1 here.
Some vegetables are not commonly grown in Kansas gardens because our climate is a challenge for them. These vegetables will often thrive in a fall-planted garden, although the results may be variable.
Chicories, related to lettuces, include endive, escarole, Italian dandelion, and radicchio. These are vegetables that do the best in cool conditions and are quite cold hardy. Radicchio in particular has best color development and flavor as the weather gets colder. While we cannot always grow vegetables of the size you might see in the grocery store, you can grow a crop that is good to use in your kitchen. Chicories are best started indoors from seed in mid- to late July and then transplanted outdoors in late August or early September.
While the leafy types of fennel grow well in the spring and early summer, if you want to try growing the bulb-forming types of fennel, the fall is the best time to grow them. The longer, more consistently cool weather will allow for the production of a better quality bulb. Bulbing fennel planted in the spring may bolt (flower) before producing a good bulb. Bulbing fennel can be started indoors and transplanted or direct seeded.
Fall or Winter Radishes
The small, spicy spring radishes are well known to Kansas gardeners, but the larger fall radishes are much less common. Many of these radishes are Chinese or Oriental radishes, such as the daikon. Other varieties include Watermelon radishes (aka Red Meat or Mantanghong varieties), Black Spanish Round radishes, and a variety of other Chinese specialty radishes. These radishes are usually large – the size of a baseball for the round types or larger than most carrots for the daikons.
Fall radishes are typically sweeter and less spicy that the spring radishes, and are often used in cooked dishes rather than just salads. Fall radishes will also store longer under similar storage conditions to turnips, carrots, and potatoes in a root cellar.
Bok Choy is an Asian green that is becoming common in grocery stores. It has crunchy, stems similar to celery and dark green leaves. This vegetable is frequently found in Asian stir fries and can be used much like celery in many dishes. Bok choy grown in the spring will often become strong flavored, even bitter quickly. It will also flower before a good quality rosette of leaves has developed. While fall grown bok choy may also bolt in a warm spell, the quality of the vegetable is much better than in the spring, in most years.
Like onions, leeks can be planted again in the fall. Leeks should be started indoors and then transplanted in the fall to provide a longer growing season. Fall planted leeks may not be as large as leeks planted in the early spring, but they are very cold hardy and can be harvested well into the winter. Some types of leeks will also overwinter successfully in southern Kansas, allowing for continued growth in the spring.