Practical planning tools for short growing seasons.
Climate-based onion planting guide for Bathurst, New Brunswick
When to Plant Onions in Bathurst
In Bathurst, onions are usually a strong local fit. Most gardeners have some room to work with this crop rather than feeling close to the edge.
Typical Planting Window
Strong fit in this climate
Use the planting dates below for onions in Bathurst.
Start indoors
March 4
Typical planting windowApril 29 – May 13
MethodTransplant
Typical days to maturity95–110
Onions are usually started indoors around March 4 and planted outdoors during the normal local window of April 29 to May 13.
Most varieties need about 95–110 days to reach maturity once they are in the garden.
Onions usually perform well in Bathurst. The practical advantage is that gardeners have some flexibility in timing and variety choice.
This crop usually has enough season to finish well here, which means the stronger results come from managing for uniformity, finish, and holding quality.
Best local strategy:
Use the normal transplant window and prioritize healthy early growth, spacing, and even moisture.
Can Onions Mature in Bathurst?
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)2089
Typical crop GDD target1300
Heat margin+789
From the usual planting window, Bathurst typically provides about 2089 growing degree days for onions. With a typical crop target of 1300, that leaves a heat margin of +789. 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
2153
+853
Comfortable
May 15
2127
+827
Comfortable
Jun 1
2000
+700
Comfortable
Jun 15
1823
+523
Comfortable
Jul 1
1555
+255
Comfortable
How Different Onion Varieties Affect Results
In Bathurst, most onion varieties are usually realistic choices. Gardeners can often choose across the maturity range without giving up much day-to-day reliability.
Varieties that often fit well here include:
Walla Walla
— large and popular, but still best when started early enough to build size
Copra
— a dependable storage onion with good all-around practicality
Redwing
— a strong red storage type where the season is reasonably supportive
Patterson
— a solid keeping onion that wants enough runway to size up well
Ailsa Craig
— more exposed in shorter seasons because it benefits from a longer finishing run
Best Onion Varieties for Bathurst
Mid-season onion varieties are usually the strongest all-around match in Bathurst. The local season can support onions, so the main choice is usually about bulb size, sweetness, color, and keeping quality.
May 20
local season starts
September 26
frost pressure returns
Less heat used2089 GDD available
Hover or tap the dots to see which recommended varieties use that much local heat.
For Bathurst, start with Redwing and Patterson for onions when you want red storage onions or long-keeping onions.
Choose Walla Walla when you want large sweet onions.
Look at Ailsa Craig and Copra when you specifically want large exhibition onions or dependable storage onions.
Compare each variety’s heat need and maturity timing against the local frost-free window before choosing what to grow.
Recommended starting point
RedwingMid-season
1300 GDD needed2089 available before frost
May 20September 26
Comfortable fit
Why this fit?
Local season fit:
Redwing leaves about 789 GDD cushion against the normal Bathurst crop heat estimate.
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.
PattersonMid-season
1300 GDD needed2089 available before frost
May 20September 26
Comfortable fit
Why this fit?
Local season fit:
Patterson leaves about 789 GDD cushion against the normal Bathurst crop heat estimate.
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.
Fastest / most cushion
Walla WallaVery early
1100 GDD needed2089 available before frost
May 20September 26
Comfortable fit
Why this fit?
Local season fit:
Walla Walla leaves about 989 GDD cushion against the normal Bathurst 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.
Also realistic
Ailsa CraigLate
1400 GDD needed2089 available before frost
May 20September 26
Comfortable fit
Why this fit?
Local season fit:
Ailsa Craig leaves about 689 GDD cushion against the normal Bathurst crop heat estimate.
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.
CopraEarly
1200 GDD needed2089 available before frost
May 20September 26
Comfortable fit
Why this fit?
Local season fit:
Copra leaves about 889 GDD cushion against the normal Bathurst crop heat estimate.
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.
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
90–95
1100
Good fit
Early
95–105
1200
Good fit
Mid-season
105–115
1300
Good fit
Late
115–120
1400
Good fit
Main risk: The usual setback here is giving away seasonal margin through late planting, slow early growth, or slower variety choice than the crop really needs.
How Frost Affects Planting Dates for Onions in Bathurst
Bathurst usually has about 129 frost-free days, with a typical last spring frost around May 20 and a typical first fall frost around September 26.
Typical last spring frostMay 20
Typical first fall frostSeptember 26
Typical frost-free days129
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.
Problems here usually come from giving up part of the season through late planting, weak early growth, or slower variety choice than the crop really needs.
In Bathurst, onions already have plenty of seasonal room when planted around April 29. In practical terms, the best spots are usually south-facing walls, sheltered gardens, raised beds, and sunnier urban lots. Cooler spots like low spots, exposed sites, and shadier yards are more likely to stay cooler and be less forgiving. For onions, warmer local sites usually help the crop get established earlier and grow a little more steadily.
Set up onions for sizing, watering, and storage
The biggest gains usually come from better planting setup, steady moisture, good sizing, and clean harvest handling rather than season extension.
Soil and planting setup
For storage crops, the best gains usually come from strong early growth and a clean finish.