Practical planning tools for short growing seasons.
Climate-based onion planting guide for Homer, Alaska
When to Plant Onions in Homer
Onions are often difficult in Homer because the local season is short enough that the crop can easily run out of time or heat before finishing well.
Typical Planting Window
Risky in this climate
Use the planting dates below for onions in Homer.
Start indoors
February 22
Typical planting windowApril 19 – May 3
MethodTransplant
Typical days to maturity95–110
Onions are usually started indoors around February 22 and planted outdoors during the normal local window of April 19 to May 3.
Most varieties need about 95–110 days to reach maturity once they are in the garden.
Onions are usually a higher-risk crop in Homer. Success tends to come from careful variety choice and the most favorable microclimates available.
Homer usually gets into the planting season for onions slightly earlier than many other Alaska locations.
Best local strategy:
Use the earliest practical starts, the fastest varieties, and the warmest protected sites available.
Can Onions Mature in Homer?
Growing degree days measure how much useful warmth typically accumulates during the season. For onions, this helps estimate whether local heat accumulation is usually enough for the crop to reach maturity on time.
Available GDD (base 45)866
Typical crop GDD target1300
Heat margin-434
From the usual planting window, Homer typically provides about 866 growing degree days for onions. With a typical crop target of 1300, that leaves a heat margin of -434. That heat shortfall means the crop usually needs the fastest approach and the warmest local conditions to have a realistic chance of finishing well.
When Is It Too Late to Plant?
When planting later than usual, this table shows how much growing degree day heat is still available from each point in the season. As planting gets pushed back, the remaining heat drops and the crop becomes less likely to mature on time.
Checkpoint
Remaining GDD
Heat margin
Fit vs typical target
Apr 15
866
-434
Usually short
Jun 1
850
-450
Usually short
Jun 15
789
-511
Usually short
Jul 1
668
-632
Usually short
How Different Onion Varieties Affect Results
In Homer, only the fastest onion varieties are realistic candidates in a typical year. Larger and later types usually run out of season before finishing well.
Varieties that often fit well here include:
Walla Walla
— large and popular, but still best when started early enough to build size
Best Onion Varieties for Homer
Onion variety choice matters in Homer, especially when slower maturity ranges start spending too much local margin. The local season can support onions, so the main choice is usually about bulb size, sweetness, color, and keeping quality.
May 10
local season starts
September 29
frost pressure returns
Less heat used866 GDD available
Hover or tap the dots to see which recommended varieties use that much local heat.
For Homer, Walla Walla
is
the most realistic onion
option
for this short-season fit.
It needs
good timing, steady early growth, and realistic expectations.
Compare each variety’s heat need and maturity timing against the local frost-free window before choosing what to grow.
Closest matches for a marginal season
Walla WallaVery early
1100 GDD needed866 available before frost
May 10September 29
Usually too long
Why this fit?
Local season fit:
Walla Walla is about 234 GDD short against the normal Homer crop heat estimate.
Best for: large sweet onions.
A large, popular onion that can be rewarding, but still needs an early enough start to build size.
Tradeoff: Needs an early enough start to build size.
GDD comparisons are a planning shortcut, not a guarantee. Soil, watering, sowing depth, pests, transplant quality, and harvest goals still affect the final result.
Varieties that didn’t make the cut
These varieties are not the main picks for Homer because they either run past the normal season or leave too little margin before frost.
ailsa craigLate
Needs1400 GDD
Homer gives866 GDD
Gap
534 GDD short
866 GDD available before frost534 more GDD needed
May 10September 29
Runs past season
Why not a main pick?
Local season fit:
ailsa craig usually needs about 534 more GDD than Homer provides before frost.
Best for: large exhibition onions.
A large onion that is more exposed in shorter seasons because it benefits from a longer finishing run.
Tradeoff: More exposed in shorter seasons.
pattersonMid-season
Needs1300 GDD
Homer gives866 GDD
Gap
434 GDD short
866 GDD available before frost434 more GDD needed
May 10September 29
Runs past season
Why not a main pick?
Local season fit:
patterson usually needs about 434 more GDD than Homer provides before frost.
Best for: long-keeping onions.
A solid keeping onion that wants enough runway to size up well before the season closes.
Tradeoff: Needs enough runway before the season closes.
redwingMid-season
Needs1300 GDD
Homer gives866 GDD
Gap
434 GDD short
866 GDD available before frost434 more GDD needed
May 10September 29
Runs past season
Why not a main pick?
Local season fit:
redwing usually needs about 434 more GDD than Homer provides before frost.
Best for: red storage onions.
A strong red onion that makes sense where the season is supportive enough for good bulb sizing.
Tradeoff: Needs a supportive season for good bulb sizing.
copraEarly
Needs1200 GDD
Homer gives866 GDD
Gap
334 GDD short
866 GDD available before frost334 more GDD needed
May 10September 29
Runs past season
Why not a main pick?
Local season fit:
copra usually needs about 334 more GDD than Homer provides before frost.
Best for: dependable storage onions.
A practical storage onion with good all-around usefulness when started early.
Tradeoff: Still needs enough season to size up.
Variety class
Typical days to maturity
Typical GDD need
Local fit
Very early
90–95
1100
Poor fit
Early
95–105
1200
Poor fit
Mid-season
105–115
1300
Poor fit
Late
115–120
1400
Poor fit
Main risk: In this location, the season is often too short for the crop to finish well before conditions turn against it.
How Frost Affects Planting Dates for Onions in Homer
Homer usually has about 142 frost-free days, with a typical last spring frost around May 10 and a typical first fall frost around September 29.
Typical last spring frostMay 10
Typical first fall frostSeptember 29
Typical frost-free days142
Minimum safe temperature28°F /
-2
°C
Onions are generally
lightly frost tolerant
and temperatures below about 28°F (
-2
°C) can slow growth or damage plants.
Onions are usually tolerant enough of cool conditions that frost dates act more like planning markers than hard limits. In practice, timing and steady early growth matter more than avoiding every light frost.
The crop usually falls short here because the season runs out before it finishes well. Late planting, cool nights, and slower varieties make that problem much worse.
Onions are usually workable in Homer, but local site warmth still influences how much margin they finish before the usual fall frost around September 29. Local gardens do not all warm and cool at the same pace. 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 onions, the best local sites often help the crop get moving earlier and make timing a little more forgiving.
Protect onions with strong starts and steady moisture
The useful setup is about strong early growth, steady moisture, and getting the crop to a clean finish.
Soil and planting setup
For storage crops, the best gains usually come from strong early growth and a clean finish.
