When to plant · 22 cities · zones 5b–7a
When to plant mustard greens in Colorado
Direct sow mustard greens around May 7 — the Colorado statewide median, counted from a last spring frost of May 7 across 493 ZIP codes and 190 NOAA stations.
The rule: Direct sow as soon as the soil can be worked in spring, and again in late summer for fall. Seed germinates fastest at 55–65 °F and may stall above 80 °F.
Colorado mustard greens, by step
Statewide median last frost May 7, first fall frost Oct 6, 2027 season. Each cultivar's own indoor lead time and days to maturity, same engine as the Plan Builder.
| Cultivar | Start indoors | Sow | First harvest | Days |
|---|---|---|---|---|
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | May 7 | Jun 6 | 30 from sow |
Tight means first harvest lands within two weeks of the median first fall frost. Statewide dates are the ZIP-weighted median of every NOAA 1991–2020 station Colorado's ZIP codes resolve to; 34 of 527 ZIPs have no datable freeze and are left out.
Mustard Greens in Colorado, city by city
Mustard greens, scheduled from each city's nearest NOAA station — the same dates as its frost page.
| City | Last frost | Sow | First harvest |
|---|---|---|---|
| Denverzone 6a | May 4 | May 4 | Jun 3 |
| Colorado Springszone 6a | May 3 | May 3 | Jun 2 |
| Aurorazone 6a | May 5 | May 5 | Jun 4 |
| Fort Collinszone 5b | May 3 | May 3 | Jun 2 |
| Lakewoodzone 6a | May 3 | May 3 | Jun 2 |
| Thorntonzone 6a | May 2 | May 2 | Jun 1 |
| Arvadazone 6a | May 5 | May 5 | Jun 4 |
| Westminsterzone 6a | May 2 | May 2 | Jun 1 |
| Greeleyzone 5b | May 2 | May 2 | Jun 1 |
| Pueblozone 6a | Apr 26 | Apr 26 | May 26 |
| Centennialzone 6a | May 5 | May 5 | Jun 4 |
| Boulderzone 6a | May 6 | May 6 | Jun 5 |
| Longmontzone 5b | May 7 | May 7 | Jun 6 |
| Castle Rockzone 5b | May 9 | May 9 | Jun 8 |
| Lovelandzone 5b | May 3 | May 3 | Jun 2 |
| Broomfieldzone 6a | May 2 | May 2 | Jun 1 |
| Grand Junctionzone 7a | Apr 28 | Apr 28 | May 28 |
| Commerce Cityzone 6a | May 3 | May 3 | Jun 2 |
| Parkerzone 5b | May 9 | May 9 | Jun 8 |
| Littletonzone 6a | May 2 | May 2 | Jun 1 |
| Brightonzone 5b | May 3 | May 3 | Jun 2 |
| Windsorzone 5b | May 3 | May 3 | Jun 2 |
What Colorado mustard greens need
Organic Seed Starter Potting MixMust have
Seed-starting mix is not potting soil with a nicer label — it is finer, lighter, and low in nutrients on purpose, because a seedling's first roots want air and moisture, not fertiliser.
72-Cell Trays with 1020 Bottoms, 5-PackMust have
The cheap black nursery trays crack after one season and flex enough to break roots when you lift them. These do not. Over five seasons the price per use is lower than the throwaways.
AG-30 Frost Protection Row Cover
AG-30 buys roughly 6 °F of frost protection while passing about 70% of light — enough to carry a crop through an early-October cold snap that would otherwise end your season two weeks short.
Ultra-Fine Garden Netting, 10×33 ft, 2 pcs
A hornworm is a moth's decision made in June. Fine mesh over the bed at transplant means the moth never lands, and you never spray anything at all.
6" Micro-Tip Pruning SnipsMust have
Ninety percent of sauce-garden cutting is snipping a pepper stem or a basil node, and a fine-tipped snip does it better than any pruner. Pulling peppers by hand tears the branch.
Digital Kitchen Scale, 11 lb, g/ozMust have
Fermentation brine is a percentage of weight, not a number of spoons. Without a gram scale you are not following a fermentation recipe — you are guessing at the one number that determines whether it is safe.
One-Touch Coffee & Spice Grinder
Dried cayenne into powder in fifteen seconds. Dedicate one to chiles — grind coffee in it afterwards and you will find out exactly how well capsaicin sticks to plastic.
Half Pint (8 oz) Regular Mouth Mason Jars, 12Must have
Eight ounces is the right jar for a sauce you use by the spoonful. Open a quart of hot sauce and you are racing the fridge; open a half-pint and you finish it while it is still good.
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Mustard Greens in Colorado: questions
When should I plant mustard greens in Colorado?
Direct sow around May 7 at the statewide median; across the state that date runs from Apr 30 in the warmest tenth of Colorado's ZIP codes to Jun 6 in the coldest. To cut the freeze risk to one year in ten, count from May 21 instead of the median last frost. Use the city table for your own town.
When is the last frost in Colorado?
The ZIP-weighted median of NOAA 1991–2020 station medians is May 7. In the warmest tenth of Colorado's ZIP codes the median last frost falls on or before Apr 30; in the coldest tenth, on or after Jun 6.
When will Colorado mustard greens be ready to harvest?
Mustard greens planted on the statewide date is ready around Jun 6: 30 days from sow.
More for Colorado
- When to plant tomatoes
- When to plant peppers
- When to plant tomatillos
- When to plant basil
- When to plant onions
- When to plant cilantro
- When to plant carrots
Mustard Greens in every state → · Colorado frost dates → · How frost-date math works →