In this week’s Ask a Master Gardener presentation, Susie Everding and Nancy Louwman reminded us that although summer days are over, the gardening season is not! There are still many crops that, if planted mid season, will grow and become tastier with cooler temperatures. Others can be planted in the fall for a head start on early spring growth.
With a bit of advance planning, Susie is able to enjoy a fall harvest, long after the garden has been cleared of many spring planted crops. By mid July, she is transplanting seedlings or direct sowing selected crops that will mature during the time left in the season, and that prefer the cooler autumn days (and nights). Kohlrabi, tatsoi, mizuna, arugula, or bokchoi are all excellent choices.
Determining Planting Dates
Seed packets indicate the number of days to maturity, generally defined as the number of days from germination (or transplantation) to first harvest; choose fast maturing varieties. Working back from an average first frost date in our area of October 13, simply check the packet for number of days to maturity. Add an additional 2-4 weeks since slower growth is expected in fall due to cooler temperatures and shorter day length. This will give a planting date.
For example, if bok choi requires 50 days to mature, plus 4 weeks (28 days), count back 78 days from Oct 13 to know when to start seeds for a fall harvest.
Online seed calculators are a helpful tool in determining when to plant. Johnny’s Seeds provides a downloadable spreadsheet as well as tips on protecting plants in the event of frosty nights.
Succession Growing in Containers
Many of Nancy’s vegetables are grown in containers as described in an earlier Ask a Master Gardener presentation, and she too extends her growing season well into the fall with succession sowing. The soil in planters must be amended as nutrients become depleted over the season. This can be done by periodically adding well rotted manure, compost or a timed release fertilizer.
Fall vegetables grown in her containers include elongated, plump Asian radishes, to be enjoyed as a roast radish crostini or golden beets, with their edible leaves and roots. Leafy greens such as arugula, Swiss chard or mache, a frost hardy green that readily self sows are also great options.
Other suggestions include kale, which can be sown in mid August and is very frost hardy, often lasting until December, or various types of spinach. Sweet and crunchy hakurei turnips, while not frost tolerant, mature in just 38 days and so are an excellent choice for late planting.
At this time of year, Nancy is also bringing in her pole beans and Jerusalem artichokes and into December will be enjoying Brussels sprouts fresh from the garden. Fall can also be welcomed with an ornamental planter including flowering kale and other autumn foliage.
Fall Planting for Spring
There are many crops that can be planted in the fall for early spring growth. These will start to grow when seeded, and then, as the days grow shorter (less than 10 hours of daylight) enter into dormancy, only to re-emerge with the longer days in spring. At our latitude, November 7 is the date on which day length reaches this point, and so Susie uses her seed calculator to count back to a planting date which will allow her tatsoi, arugula, kale and radish to establish themselves before entering winter dormancy.
Some gardeners may have noticed that many types of seeds manage this process without assistance! If lettuce, for example, has been allowed to go to seed over the summer, you may be rewarded with tiny seedlings in your garden come spring.
With another week of warm weather on the way, perhaps this is the year to plan and plant your spring garden in the fall!