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Ask a Master Gardener: Go green this spring with spinach

by Peter Sutter | September 25, 2022 at 4:00 a.m.

A couple of weeks ago, I wrote an article about fall spinach. Well if you have any seed left, here is a idea for you. In fact, it might be an idea even if you have to buy some seed.

There are many things that can be enjoyed in the spring with a little planning now. Spinach is one of my favorites. After a winter of store bought greens, it is nice to see green, eatable green, in the garden even before the ground is workable. If you had limited success with spring-planted spinach, now is the time to plant it as an "overwinter" crop instead. Since spinach is a cool-season crop that does best when days are less than 14 hours long and temperatures don't exceed 80 degrees, overwintering your spinach crop will ensure an extra early spring start.

Although many believe heat is what causes spinach to bolt, day length actually initiates this flowering response in spinach. Flowering in most varieties is "switched on" by days about 14 hours long, which occurs around the end of April in our area. By the time warm spring weather arrives and the spinach is growing nicely, the days have become long enough to initiate flowering. Then days above 80 degrees speed up the plants' metabolism, accelerating the rate of bolting.

The last week of September into the first of October is the time to plant spinach for overwintering. Spinach is a cold-hardy crop that can withstand hard frosts with accompanying temperatures as low as 20 degrees, but if you would like to keep it through the winter for an early spring treat, a few steps should be taken.

First, pick a spot in the garden that will be out of the way and not disturbed during the winter. Also, keep in mind early spring planting plans. It will not be good to have the spinach patch where it will be in the way so you have to work around it to start the spring garden. Work in a 2- to 4-inch layer of compost into the area you have decided on.

Cold-tolerant spinach overwinters best if the plants are 2-4 inches wide by the time night temperatures start remaining toward the freezing mark. Give the plants time to reach this size by sowing now. Spinach seed often has spotty germination rate when planted in late summer and fall due to warm, dry soil conditions. You can boost germination rates by cooling the soil the week before sowing; just water the bed well and then place straw over the soil to shade it. The straw will be used later for a protective mulch.

Sow the spinach seeds abundantly, about an inch apart, and then thin the seedlings to 6 inches once they develop three sets of leaves. Keep the soil moist. After one or two frosts, cover the spinach with a heavy straw mulch, 8-10 inches is recommended.

Next spring, once the days begin to lengthen and daytime temperatures consistently rise above freezing, remove a couple of inches of straw at a time over a period of a few weeks until all the straw has been removed. Begin harvesting leaves regularly when the plants actively put out new growth.

Happy gardening!

Peter Sutter is a lifelong gardening enthusiast and a participant in the MU Extension's Callaway County Master Gardener Program. Gardening questions can be sent to [email protected]

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