Kale is a hardy cool-season crop, so spring kale goes in before your last frost. NC State Extension says to plant about 4 weeks before the average last spring frost; Utah State says transplants go out 4 to 5 weeks before the last frost-free date; UMN says seed can go in as soon as the soil can be worked. Texas A&M's table gives 2 to 6 weeks before the frost-free date. Young plants handle about 25°F without serious damage (USU), and kale grows best when temperatures stay at or below about 75°F (USU), so the goal is to harvest before summer heat.
Kale is easier to time in spring than most crops, because it is hardy enough to go out early and fast enough to give baby leaves within a few weeks. The usual mistake is the same one gardeners make with spinach: waiting until the weather feels warm. Kale planted late runs into hot, dry weather, which UMN and USU both link to bitter, tough leaves. This guide covers spring planting; for a fall crop, see when to plant spinach and kale in fall.
Spring dates by last frost
The table counts back from your average last spring frost. The indoor column assumes you transplant about four weeks before the frost date and start seeds 5 to 6 weeks before that (USU says transplants take 5 to 6 weeks to grow; UMN says about four weeks). Our planting calendar shows a direct-sowing window from about four weeks before your last frost to several weeks after it.
| Average last spring frost | Start seeds indoors | Transplant or sow outdoors (NC State, USU) | Texas A&M window (2 to 6 weeks before) |
|---|---|---|---|
| Mar 1 | Dec 21 – Dec 28 | Jan 25 – Feb 1 | Jan 18 – Feb 15 |
| Mar 15 | Jan 4 – Jan 11 | Feb 8 – Feb 15 | Feb 1 – Mar 1 |
| Apr 1 | Jan 21 – Jan 28 | Feb 25 – Mar 4 | Feb 18 – Mar 18 |
| Apr 15 | Feb 4 – Feb 11 | Mar 11 – Mar 18 | Mar 4 – Apr 1 |
| May 1 | Feb 20 – Feb 27 | Mar 27 – Apr 3 | Mar 20 – Apr 17 |
| May 15 | Mar 6 – Mar 13 | Apr 10 – Apr 17 | Apr 3 – May 1 |
| Jun 1 | Mar 23 – Mar 30 | Apr 27 – May 4 | Apr 20 – May 18 |
In northern gardens, UMN gives a simple version: start seeds indoors in early April, or sow outdoors once the soil can be worked. Warm-winter areas grow kale through the cool months instead of in spring; see the Texas and Florida section below.
Seeds or transplants?
Both work. Direct seeding is cheap and quick; transplants give you a head start and get leaves to the table before the weather turns hot.
| Detail | Extension guidance |
|---|---|
| Seed depth | About ¼ to ½ in (UMN); ½ in deep and 1 in apart (NC State) |
| Thinning | 8 to 12 in between plants (UMN); 1 ft (NC State) |
| Transplant spacing | About 12 in apart in rows 2 ft apart (USU); NC State says 6 in apart, thinned later |
| Hardening off | Reduce water and temperature for two to three days before transplanting (UMN) |
| Days to harvest | Baby greens in 20 to 30 days; full-size leaves in 50 to 75 days (NC State); 50 to 80 days (Texas A&M) |
How much cold spring kale can take
USU says young kale plants are not seriously damaged by temperatures down to about 25°F, and mature plants are extremely hardy. That is why kale can go out a month before the last frost. A sudden hard freeze right after transplanting can still set back tender seedlings; a frost cloth or row cover over the bed is a cheap insurance policy for the first couple of weeks.
Beat the heat
Spring kale's real deadline is summer. USU says kale grows best when temperatures do not exceed 75°F, and that high summer temperatures make the leaves bitter; UMN advises harvesting the spring crop before hot, dry weather sets in, and notes that heat and water stress cause bitter flavor. To stretch the spring harvest:
- Plant on time. Use the dates above rather than waiting for warm weather.
- Keep it watered. NC State notes kale prefers plentiful, consistent moisture; drought hurts leaf quality and flavor.
- Mulch. NC State suggests a 2 to 3 inch layer of organic mulch such as straw to hold moisture.
- Pick often. Take the lower, outer leaves and let the center keep growing.
- Plan the fall crop. When spring kale fades, sow again in summer for fall: NC State says about six weeks before your first fall frost.
Texas, Florida and mild-winter areas
Where winters are mild, kale is a fall-to-spring crop. University of Florida IFAS lists kale from August through February in North Florida, September through February in Central Florida and September through December in South Florida. Texas A&M's vegetable table gives spring planting 2 to 6 weeks before the frost-free date and fall planting 8 to 12 weeks before the first frost. Our what to plant in winter guide has more cool-season options for warm regions.
Where kale goes in the garden
Kale belongs to the cabbage family, so it shares pests and rotation needs with broccoli and cabbage; UMN suggests not planting cabbage-family crops in the same spot more than once every four years. See what to plant with kale for companions, when to plant broccoli for its cousins' timing and when to plant spinach for another early green. For another long-season green, see when to plant Swiss chard.
Frequently asked questions
When should I plant kale in spring?
About 4 weeks before your average last spring frost (NC State), or 4 to 5 weeks before for transplants (USU). UMN says seed can go in as soon as the soil can be worked; Texas A&M gives 2 to 6 weeks before the frost-free date.
Can kale survive a frost after planting?
Usually. USU says young plants are not seriously damaged by temperatures down to about 25°F, and mature plants are very hardy. Cover new transplants if a hard freeze is forecast.
When should I start kale seeds indoors?
About 4 to 6 weeks before you plan to transplant: USU says transplants take 5 to 6 weeks to grow, and UMN says about four weeks. For transplanting a month before your last frost, that means about 9 to 10 weeks before the frost date.
Is it too late to plant kale in May?
In warm areas, often yes for a spring crop, because heat makes kale bitter (USU, UMN). In cool northern gardens a May sowing can still work. Otherwise wait and plant a fall crop about six weeks before your first fall frost (NC State).
How long does kale take to grow?
Baby greens in about 20 to 30 days and full-size leaves in about 50 to 75 days (NC State). Texas A&M lists 50 to 80 days.
Why is my spring kale bitter?
Heat and water stress are the usual causes (UMN, USU). Plant earlier, keep the soil evenly moist, mulch, and harvest before summer heat.
Enter your last frost date to see your kale window and when every other crop can go in.
Open itSources
- Virginia Cooperative Extension, "Companion Planting in Gardening" (SPES-620P)
- University of Maryland Extension, "Vegetable Succession and Companion Planting"
- Oregon State University Extension, "Companion Planting"
- Penn State Extension, "Herbs Make Good Plant Partners and Companions"
- University of Minnesota Extension, "Planting the vegetable garden"
- USDA Plant Hardiness Zone Map
- NOAA NCEI U.S. Climate Normals (frost/freeze data)
- NC State Extension, "Kale"
- Utah State University Extension, "How to Grow Kale in Your Garden"
- University of Minnesota Extension, "Growing collards and kale in home gardens"
- Texas A&M AgriLife Extension, "Texas Home Vegetable Gardening Guide" (Tables 8 and 9)
- University of Florida IFAS Gardening Solutions, "What to Plant by Month" (text version)
Pairings are summarized in our own words from extension-service guidance. Research support for many companion effects is limited, so treat them as good habits, not guarantees.