When to plant tomatoes in Fort Collins: 14 May – 1 July

In Fort Collins, tomato: sow for seedlings from 2 March to 10 May; plant into a greenhouse from 23 April to 1 July; plant out into open ground from 14 May to 1 July. For plants and seeds, the places nearby include Bath Garden Center and Nursery (garden centre, 3 km) and Fort Collins Nursery (garden centre, 4 km); addresses and opening hours are below.

Tomato in Fort Collins: soil, season and weather

In Fort Collins the soil, not frost, sets the date: the last frost is over around 25 April, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 14 May, 19 days later.

Last spring frost	25 April
Top 7 cm of soil at 15 °C	14 May, 19 days after the last frost
Into an unheated greenhouse	23 April – 1 July; April outside: 1.1 °C at night, 17.4 °C by day; card 16–27 °C
First autumn frost	21 October, 160 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	23 July – 9 September
Days left for picking	90
Daylight	12:15 on 23 March, 14:23 on 14 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, October, has 4 rainy days

Tomato in Fort Collins: care after planting

Planted on 14 May: in the first weeks water every 4 days.

Feeding, by the card’s schedule from that day:

14 May — feed: balanced (NPK)
11 June — feed: nitrogen

Pests and diseases of tomato to watch for:

Dates count from the first planting day of the window above; a later planting moves them by as many days.

Weather in Fort Collins during the tomato season

Days average above the tomato card's 16–27 °C in June–September (27.7–31.6 °C). Nights average below 16 °C in May, June and August–October (3.8–15.2 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	21.1	6.4	95	13	14:25
June	28.4	12.7	40	8	15:03
July	31.6	16.2	37	7	14:48
August	30.5	15.2	34	7	13:49
September	27.7	11.2	22	4	12:30
October	18.8	3.8	20	4	11:11

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Fort Collins, Grand Junction is 19 days earlier and Cheyenne 11 days later.

City	Distance	Date	Difference
Cheyenne	69 km	25 May – 23 June	11 days later
Denver	90 km	8 May – 25 June	6 days earlier
Colorado Springs	192 km	13 May – 25 June	1 day earlier
Pueblo	258 km	28 April – 8 July	16 days earlier
Grand Junction	340 km	25 April – 7 July	19 days earlier
Rapid City	420 km	20 May – 22 June	6 days later

Where to buy tomato plants and seeds near Fort Collins

Buy plants ready to set out from 14 May to 1 July (from 23 April to 1 July for an unheated greenhouse); seed for raising your own is sown from 2 March to 10 May. Within 15 km of Fort Collins OpenStreetMap lists 10 garden centres, 4 farm-supply shops, 2 plant nurseries, 3 markets and 6 farm shops (collected 28 October 2026).

Bath Garden Center and Nursery — garden centre
East Prospect Road 2000, 80525 Fort Collins · Mon–Fri 08:00–19:00; Sat 08:00–18:00; Sun 09:00–17:00 · 3 km · bathgardencenter.com
Fort Collins Nursery — garden centre
East Mulberry Street 2121, 80524 Fort Collins · Mon–Sat 09:00–17:00; Sun 10:00–17:00 · 4 km · fortcollinsnursery.com
Donath Lake Greenhouses — garden centre
South Lemay Avenue 8420, 80525 Fort Collins · Apr–Jun 09:00–17:00 · 9 km · donathlakegreenhouses.com
Gulley Greenhouse and Garden Center — garden centre
South Shields Street 6029, 80526 Fort Collins · Mon–Sun 09:00–18:00 · 6 km · gulleygreenhouse.com

Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

Questions