Ask a Master Gardener: Cool season planting starts in March

(Posted March 11, 2021)

Hooray for St. Patrick’s Day! Many consider the last half of March to be the official start of the growing season, when you can start cool season flowers and vegetables. Do you know the difference between cool season veggies and warm season veggies? It’s exactly what you’d expect from the name.

Cool season plants prefer the cooler temps of very early spring, 60’s and 70’s with chilly nights. They are unfazed by late frosts, even though they might suffer some damage. However, if a hard freeze or several nights of frost are predicted, they appreciate being covered until the morning sun warms them up a bit. Cool season plants tell you when their short season is over. They bolt, meaning they get tall and lanky and produce seed. Many become tough or bitter when eaten.

Warm season plants prefer temperatures up into the 80’s, and they want balmy nights over 50 degrees. They will not survive a frost without protection. If planted too early, they will shiver until the soil warms sufficiently for them to start growing. Tomatoes are the No. 1 warm season vegetable in Ohio.

Ohio has two cool seasons–spring and fall. Plant the first cool season crop about six weeks before the local frost-free date.  The second cool crop is planted about six weeks before the first anticipated frost date (early to mid-August).

What to plant? There are so many options, it is hard to choose. Cool season flowers include pansies, violas, stock, snapdragons, and more. This is a great time to start your porch planters with pansies and violas. In late May or June, replace your cool flowers with warm flowers, and you’ll have many extra weeks of bloom. Vegetables offer even more options. Lettuce, arugula, kale, endive and almost all leafy greens love a good shiver. Radishes, beets, peas, carrots, broccoli, potatoes and onions also like a chilly start. Cool season herbs include parsley, cilantro, fennel and others.

When planting so early in the spring, it is important to protect the garden bed. If the garden is spongy wet, don’t walk in it any more than necessary. Plant only the perimeter if the center is too sodden. Don’t try to till the soil when it is wet; it is easily compacted and will turn into hard, unproductive clumps. If your garden contains plant material from last year, remove what you can and plant around what’s left. Don’t worry about fertilizer unless you know your soil is depleted and then use a light hand. Most cool season veggies are not heavy feeders, and fertilizing can easily be overdone.

Go ahead! Grab a seed packet and try some early veggies. You will be eating fresh produce in just a few weeks.

This column is written by the Madison County Master Gardeners. Watch for details about their new Ask A Master Gardener Help Line, coming soon.

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