What Grows in Robertson, Wyoming

Robertson sits in USDA hardiness zones 5a-6b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.

Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Apr 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 6 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.

The last hard freeze (28°F) in Robertson typically lands around May 10, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.

The first hard freeze (28°F) in Robertson typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point most tender summer crops finish. Lighter frosts usually reach a couple of weeks earlier, so watch the forecast from late summer on and harvest or cover tender plants before the first cold night.

Robertson's zones 5a-6b support a wide range — strong performers include Potato, Indian Paintbrush, Cottonwood, Rhubarb, and Chokecherry. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.

Officially, Robertson sits in USDA zones 5a-6b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.

The federal record around Robertson is light — 45 documented sites across the 9 federal source types we checked — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.

With about 149 frost-free days between hard freezes, Robertson rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder, cold frames and low tunnels more, and quick-maturing varieties make the arithmetic work. Starting transplants indoors ahead of the May 10 hard-freeze normal stretches the season without touching the calendar.