Practical planning tools for short growing seasons.
Climate-based swiss chard planting guide for Jackson, Wyoming
When to Plant Swiss Chard in Jackson
Swiss chard is usually a good match for the season in Jackson. Gardeners generally have enough margin to think about preference and quality, not just speed.
Typical Planting Window
Strong fit in this climate
Use the planting dates below for swiss chard in Jackson.
Optional indoor start
May 23
Typical planting windowMay 31 – June 20
MethodDirect sow or transplant
Typical days to maturity55–65
Swiss chard can usually be started indoors around May 23 or sown directly during the normal local planting window of May 31 to June 20.
Most varieties need about 55–65 days to reach maturity.
Swiss chard is usually a dependable choice in Jackson. Normal timing and realistic variety choice are usually enough to produce dependable results.
This crop is usually dependable here, though the difference between decent and excellent results still comes from steady growth and harvest stage.
Best local strategy:
Treat the season as supportive, then focus on consistency and crop quality more than simple maturity insurance.
Can Swiss Chard Mature in Jackson?
Growing degree days measure how much useful warmth typically accumulates during the season. For swiss chard, this helps estimate whether local heat accumulation is usually enough for the crop to reach maturity on time.
Available GDD (base 40)1527
Typical crop GDD target750
Heat margin+777
From the usual planting window, Jackson typically provides about 1527 growing degree days for swiss chard. With a typical crop target of 750, that leaves a heat margin of +777. That heat margin usually gives the crop a dependable buffer, so gardeners have some flexibility in planting date and variety choice without pushing the crop close to the edge.
When Is It Too Late to Plant?
If planting later than usual, this table shows how much growing degree day heat is still available from each point in the season. It is most useful for judging how much flexibility you still have before the crop starts losing margin.
Checkpoint
Remaining GDD
Heat margin
Fit vs typical target
Apr 15
2345
+1595
Comfortable
May 1
2333
+1583
Comfortable
May 15
2262
+1512
Comfortable
Jun 1
2098
+1348
Comfortable
Jun 15
1915
+1165
Comfortable
Jul 1
1652
+902
Comfortable
How Different Swiss Chard Varieties Affect Results
Swiss chard usually has enough season here that maturity speed is not the main issue. In Jackson, the more useful differences are leaf color, plant size, and whether you want baby leaves or larger mature plants. In practice, steady growth and harvest style matter more than shaving a few days off maturity.
Varieties that often fit well here include:
Barese
— a quicker compact type that fits tighter seasons well
Perpetual Spinach
— a leaf-beet type that gives spinach-like greens with more staying power through warm weather than true spinach
Bright Lights
— widely grown and practical where gardeners want dependable mixed-color harvests
Rhubarb Chard
— a red-stemmed chard that adds color while keeping the same general harvest style as standard chard
Fordhook Giant
— vigorous and productive, but usually benefits from a little more runway than the quickest chards
Peppermint
— a specialty chard chosen mostly for stem color and visual interest rather than the safest or fastest harvest
Best Swiss Chard Varieties for Jackson
Swiss chard variety choice in Jackson is mostly about plant size, stem color, harvest style, and how quickly you want usable leaves.
June 20
local season starts
August 31
frost pressure returns
Less heat used1527 GDD available
Hover or tap the dots to see which recommended varieties use that much local heat.
For Jackson, start with Bright Lights and Rhubarb Chard for swiss chard when you want a dependable colorful chard mix or red stems and colorful harvests.
Choose Barese and Perpetual Spinach when you want quick compact chard harvests or spinach-like greens with better heat staying power.
Look at Fordhook Giant and Peppermint when you specifically want larger green chard plants and heavier harvests or specialty stem color.
Compare each variety’s heat need and maturity timing against the local frost-free window before choosing what to grow.
Recommended starting point
Bright LightsEarly
750 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Bright Lights leaves about 777 GDD cushion against the normal Jackson crop heat estimate.
Best for: dependable color mix.
A practical, widely grown chard mix that gives most gardeners the best balance of reliability, color, and usable harvests.
Tradeoff: Not the fastest or largest single-purpose chard choice.
Rhubarb ChardEarly
750 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Rhubarb Chard leaves about 777 GDD cushion against the normal Jackson crop heat estimate.
Best for: red-stemmed chard.
A colorful chard that works well when gardeners want red stems without changing the basic harvest style.
Tradeoff: Chosen for color as much as performance.
Fastest / most cushion
BareseVery early
650 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Barese leaves about 877 GDD cushion against the normal Jackson crop heat estimate.
Best for: quick compact harvests.
A faster, compact chard that is useful when you want the safest path or less pressure on the season.
Tradeoff: Less about large plants and more about speed.
Perpetual SpinachVery early
650 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Perpetual Spinach leaves about 877 GDD cushion against the normal Jackson crop heat estimate.
Best for: spinach-like greens.
A leaf-beet type that gives spinach-like harvests with more staying power through warm weather than true spinach.
Tradeoff: Not true spinach and has a chard-like character.
Also realistic
Fordhook GiantMid-season
850 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Fordhook Giant leaves about 677 GDD cushion against the normal Jackson crop heat estimate.
Best for: larger plants and heavier harvests.
A vigorous green chard that can be productive, but it makes more sense when you are comfortable giving it a little more room than the quickest types.
Tradeoff: Needs more room and time than compact chard types.
PeppermintMid-season
850 GDD needed1527 available before frost
June 20August 31
Comfortable fit
Why this fit?
Local season fit:
Peppermint leaves about 677 GDD cushion against the normal Jackson crop heat estimate.
Best for: specialty stem color.
A specialty chard chosen mostly for visual interest, stem color, and mixed plantings rather than maximum short-season safety.
Tradeoff: More about appearance than the safest harvest path.
GDD comparisons are a planning shortcut, not a guarantee. Soil, watering, sowing depth, pests, transplant quality, and harvest goals still affect the final result.
Variety class
Typical days to maturity
Typical GDD need
Local fit
Very early
50–55
650
Good fit
Early
55–65
750
Good fit
Mid-season
65–75
850
Good fit
Main risk: When this crop underperforms in Jackson, the culprit is usually timing or variety choice rather than the climate itself.
How Frost Affects Planting Dates for Swiss Chard in Jackson
Jackson usually has about 72 frost-free days, with a typical last spring frost around June 20 and a typical first fall frost around August 31.
Typical last spring frostJune 20
Typical first fall frostAugust 31
Typical frost-free days72
Minimum safe temperature28°F /
-2
°C
Swiss chard is generally
somewhat frost tolerant
and temperatures below about 28°F (
-2
°C) can slow growth or damage plants.
Swiss chard is usually tolerant enough of cool conditions that light frost is not the main concern. The more useful question is how early planting affects establishment and overall crop quality.
When this crop underperforms in Jackson, the culprit is usually timing or variety choice rather than the climate itself.
In Jackson, the local season usually gives swiss chard plenty of breathing room when planting happens around June 13. For a better local margin, gardeners usually do best in south-facing walls, sheltered gardens, raised beds, and sunnier urban lots. Cooler spots like low spots, exposed sites, and shadier yards often make timing tighter. For swiss chard, the best local sites often help the crop get moving earlier and make timing a little more forgiving.
Set up swiss chard for steady growth and pest protection
The better results usually come from steady growth, pest protection, and avoiding early setbacks.
Transplant support
Strong young plants help avoid slow starts and uneven sizing.