When to plant · 22 cities · zones 5b–7a
When to plant tomatillos in Colorado
Start Tomatillo seeds indoors around Mar 26 and transplant around May 14 — the Colorado statewide median, counted from a last spring frost of May 7 across 493 ZIP codes and 190 NOAA stations.
The rule: Six weeks indoors, transplant after the last frost, and give each plant 30 inches and a large cage.
Colorado tomatillos, 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 | Plant out | First harvest | Days |
|---|---|---|---|---|
| TomatilloToma Verde | Mar 26 | May 14 | Jul 23 | 70 from transplant |
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.
Tomatillos in Colorado, city by city
Tomatillo, scheduled from each city's nearest NOAA station — the same dates as its frost page.
| City | Last frost | Start indoors | Plant out | First harvest |
|---|---|---|---|---|
| Denverzone 6a | May 4 | Mar 23 | May 11 | Jul 20 |
| Colorado Springszone 6a | May 3 | Mar 22 | May 10 | Jul 19 |
| Aurorazone 6a | May 5 | Mar 24 | May 12 | Jul 21 |
| Fort Collinszone 5b | May 3 | Mar 22 | May 10 | Jul 19 |
| Lakewoodzone 6a | May 3 | Mar 22 | May 10 | Jul 19 |
| Thorntonzone 6a | May 2 | Mar 21 | May 9 | Jul 18 |
| Arvadazone 6a | May 5 | Mar 24 | May 12 | Jul 21 |
| Westminsterzone 6a | May 2 | Mar 21 | May 9 | Jul 18 |
| Greeleyzone 5b | May 2 | Mar 21 | May 9 | Jul 18 |
| Pueblozone 6a | Apr 26 | Mar 15 | May 3 | Jul 12 |
| Centennialzone 6a | May 5 | Mar 24 | May 12 | Jul 21 |
| Boulderzone 6a | May 6 | Mar 25 | May 13 | Jul 22 |
| Longmontzone 5b | May 7 | Mar 26 | May 14 | Jul 23 |
| Castle Rockzone 5b | May 9 | Mar 28 | May 16 | Jul 25 |
| Lovelandzone 5b | May 3 | Mar 22 | May 10 | Jul 19 |
| Broomfieldzone 6a | May 2 | Mar 21 | May 9 | Jul 18 |
| Grand Junctionzone 7a | Apr 28 | Mar 17 | May 5 | Jul 14 |
| Commerce Cityzone 6a | May 3 | Mar 22 | May 10 | Jul 19 |
| Parkerzone 5b | May 9 | Mar 28 | May 16 | Jul 25 |
| Littletonzone 6a | May 2 | Mar 21 | May 9 | Jul 18 |
| Brightonzone 5b | May 3 | Mar 22 | May 10 | Jul 19 |
| Windsorzone 5b | May 3 | Mar 22 | May 10 | Jul 19 |
What Colorado tomatillos need
Toma Verde Tomatillo SeedMust have
Salsa verde is not a green tomato sauce — it is a tomatillo sauce, and the difference is the tartness and the natural pectin that makes it cling. There is no substitute.
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.
Seedling Heat Mat + Digital ThermostatMust have
Peppers germinate on soil temperature, not air temperature. At 65 °F a habanero takes a month and half of them rot; at 85 °F it is up in eight days. The thermostat is the half that matters.
T8 Full-Spectrum Grow Lights, 1 ft 4-packMust have
A south window in March delivers a fraction of the light a pepper seedling needs, and the plant tells you by stretching. Two inches of LED above the canopy for 16 hours a day fixes it permanently.
5-Gallon Fabric Grow Bags, 5-Pack
Fabric pots air-prune roots and drain faster than a plastic pot can, which is the entire reason container tomatoes fail. Five gallons is the honest minimum for a pepper; a tomato wants ten.
Ocean Forest Potting SoilMust have
Pre-charged with enough nutrition to carry a transplant for its first month without feeding, which is exactly the window when most container plants stall.
Organic Tomato-Tone 3-4-6 with 8% CalciumMust have
The NPK ratio is the point: low nitrogen, higher potassium. Feed a tomato a high-nitrogen lawn fertiliser and you get a magnificent six-foot plant with four tomatoes on it.
58" Square Tomato Cages, 3-PackMust have
The conical wire tomato ring from the hardware store is 33 inches tall and an indeterminate San Marzano will laugh at it in July. Height and square geometry are what actually hold a loaded plant.
Garden Harvest Basket with Tool Caddy
A harvest basket that doubles as a colander means the hose rinse happens in the garden, and the dirt stays outside. On a 20-pound tomato day that is a genuine time saving.
Stainless Steel Food Mill, 3 discsMust have
A blender pulverises tomato skins and seeds into the sauce, which is where bitterness comes from. A mill separates them out — no blanching, no peeling, no ice bath. It removes an entire hour from sauce day.
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Tomatillos in Colorado: questions
When should I plant tomatillos in Colorado?
Transplant around May 14 at the statewide median; across the state that date runs from May 7 in the warmest tenth of Colorado's ZIP codes to Jun 13 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 do I start tomatillos seeds indoors in Colorado?
Around Mar 26 for Tomatillo: 6 weeks before the statewide median last frost, on soil held at 75–85 °F.
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 tomatillos be ready to harvest?
Tomatillo planted on the statewide date is ready around Jul 23: 70 days from transplant.
More for Colorado
- When to plant tomatoes
- When to plant peppers
- When to plant basil
- When to plant onions
- When to plant cilantro
- When to plant carrots
- When to plant mustard greens
Tomatillos in every state → · Colorado frost dates → · How frost-date math works →