When to Plant Beet Seeds: Spring and Fall

Step 1: Wait for 40 F soil

Beet seed needs soil at 40 F or warmer. Utah State University Extension says to plant 2 to 3 weeks before the last frost, with soil at least 40 F before sowing. A cheap soil thermometer pushed into the bed answers it in a minute.

The comfortable range is wider than you might expect. The same fact sheet puts the best sprouting range at 55 to 75 F, with seedlings up in 7 to 14 days. University of California extension in Sacramento gives 50 to 86 F as the best range, with 95 F as the ceiling. Germination drops above 80 F.

Step 2: Know when to plant beet seeds in spring

Sow your first beets 2 to 4 weeks before the last spring frost. Utah State's figure is 2 to 3 weeks, and Illinois Extension says beets are fairly frost hardy and can be planted 30 days before the frost-free date. Put the two together and the window runs from about 4 weeks to 2 weeks before your last frost.

Take a last frost of May 10. Thirty days back is April 10, and 14 days back is April 26. Your spring window is April 10 to April 26, as long as the soil has reached 40 F by then. If the bed is still cold on April 10, wait for it. A week of waiting is cheap.

Sowing too early has its own cost. Beets planted too early can flower prematurely, because they need a period of chill to form flower stalks (Utah State). University of California extension says two to three weeks below 50 F after several true leaves can start flower stalks before the roots mature.

Step 3: Sow the seed clusters and thin them

Plant seed about 1/2 inch deep. University of California extension gives 1/2 inch deep and 1 to 2 inches apart, with rows at least 12 inches apart. Cover lightly and water. Seedlings usually come up in 5 to 14 days.

Each beet seed is really a small cluster. California extension says it usually holds 2 to 5 seeds, so one seed can send up several plants. That is why thinning matters. Thin when seedlings are 1 to 2 inches tall, then again at 3 to 4 inches to a final spacing of about 4 inches, cutting the weaker plants instead of pulling them. The thinnings go in the salad bowl.

Then keep sowing. Illinois Extension suggests successive plantings at 3-to-4-week intervals until midsummer, while Utah State says many gardeners plant at 2 to 3 week intervals. If you start on April 10 and sow every 3 weeks, your next sowings land on May 1 and May 22.

Beets reward the gardener who plants a little often, not a lot once.

Indoors or in the ground, and why seed stays down

Sow beets in the garden, because they are usually direct seeded rather than started indoors and transplanted, per California extension.

When seed does not come up, the sources point to four causes.

• Crusted soil. Work organic matter into clay soil to help avoid surface crusting after rain (California).
• Dry seedbed. Lay floating row cover or burlap over the row and keep it moist until seedlings emerge, which typically takes 5 to 14 days (California).
• Seed coat chemicals. Rinse the seed in a sieve under cold running water, then sow right away, says California extension. Plant extra seed of golden beets, which it says germinate poorly.
• Damping off. A University of Maine extension answer names this fungal infection in wet conditions, which attacks germinating seeds and new seedlings. Its fixes are germinating seed indoors where you control the environment, buying nursery seedlings, or rotating the bed and hoping for drier weather.

Soil temperature belongs on the list too. Utah State says germination drops above 80 F.

Step 4: Set the fall cutoff, then back it up 18 days

Fall beets are counted back from the first killing frost. Maryland Extension says to sow up until 6 weeks before the first killing frost. With a first frost of October 20, 6 weeks is 42 days, which is September 8.

The cutoff is the last day, not the best one. Maryland says beets are harvested 50 to 60 days from sowing, and Utah State says roots mature in 60 to 80 days. A beet sown on September 8 has only 42 days before the frost, so it falls 8 to 18 days short. Give a full 60 days instead. Sixty days before October 20 is August 21, so your fall window runs August 21 to September 8.

Heat matters in late summer too. Beets grow best when temperatures do not exceed 85 F, according to Utah State. Keep the seedbed moist and shaded until the plants are up.

In the mildest parts of the country the fall window sits later. University of California extension for Sacramento lists late February to early April for a late-spring harvest and mid-August to early October for a fall to early-winter harvest. It also says late fall sowings may not reach full size before cold slows their growth.

Step 5: Turn your frost dates into beet dates

Pick the date from your own frost dates, not from a zone number. The sums above work for any last frost and any first frost. Swap in your date and subtract 30 days, 14 days, 42 days or 60 days.

One honest limit. If your county extension office already publishes a beet planting date for your town, use it. Free charts and printables are enough for one beet row.

A printed plan is for gardeners who want their own dates, for every crop, on one page. The Winter Plan has countback charts with rows for your own crops, so add beets if they are not listed, using the dates from Steps 2 and 4. A table of last and first freeze dates (10, 50 and 90 %) for 108 NOAA stations is in the file, so it works in any US zone. In spring the succession waves page holds each beet sowing, and in fall the countdown holds the cutoff. The notes for next winter page is where you write what to change.