Practical planning tools for short growing seasons.
Climate-based watermelon planting guide for Red Lake, Ontario
When to Plant Watermelons in Red Lake
Watermelons are a more demanding choice in Red Lake, usually favoring only the quickest and most climate-appropriate approaches.
Typical Planting Window
Risky in this climate
Use the planting dates below for watermelons in Red Lake.
Optional indoor start
May 4
Typical planting windowJune 3 – June 13
MethodDirect sow or transplant
Typical days to maturity80–100
Watermelons can usually be started indoors around May 4 or sown directly during the normal local planting window of June 3 to June 13.
Most varieties need about 80–100 days to reach maturity.
Watermelons are challenging in Red Lake. Gardeners who succeed usually stack the odds with the fastest varieties, the best timing, and the warmest sites they have.
Within Ontario, Red Lake usually reaches planting time for watermelons a little later than many comparable locations.
Best local strategy:
Treat this as a higher-risk crop and rely on earliness, warmth, and protection wherever possible.
Can Watermelons Mature in Red Lake?
Growing degree days measure how much useful warmth typically accumulates during the season. For watermelons, this helps estimate whether local heat accumulation is usually enough for the crop to reach maturity on time.
Available GDD (base 50)1129
Typical crop GDD target1350
Heat margin-221
From the usual planting window, Red Lake typically provides about 1129 growing degree days for watermelons. With a typical crop target of 1350, that leaves a heat margin of -221. 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
1176
-174
Usually short
Jun 1
1140
-210
Usually short
Jun 15
1035
-315
Usually short
Jul 1
857
-493
Usually short
How Different Watermelon Varieties Affect Results
In Red Lake, very early watermelon varieties are usually the safest choice because they leave the least room for the season to turn against you. Slower classes are much less forgiving here.
Varieties that often fit well here include:
Sugar Baby
— the classic small short-season watermelon and one of the safest starting points where season length is limited
Blacktail Mountain
— a practical early watermelon that is often chosen specifically for cooler or shorter climates
Best Watermelon Varieties for Red Lake
Very early watermelon varieties are usually the strongest all-around match in Red Lake. Local season length still matters, especially when slower varieties need more time to size up or finish cleanly.
May 25
local season starts
September 27
frost pressure returns
Less heat used1129 GDD available
Hover or tap the dots to see which recommended varieties use that much local heat.
For Red Lake, start with Sugar Baby and Blacktail Mountain for watermelons when you want small short-season watermelons or cooler-climate watermelon success.
Compare each variety’s heat need and maturity timing against the local frost-free window before choosing what to grow.
Recommended starting point
Sugar BabyVery early
1100 GDD needed1129 available before frost
May 25September 27
Tight fit
Why this fit?
Local season fit:
Sugar Baby leaves about 29 GDD cushion against the normal Red Lake crop heat estimate.
Best for: small short-season watermelons.
The classic small short-season watermelon and one of the safest starting points where season length is limited.
Tradeoff: Smaller and less ambitious than larger classic watermelon types.
Blacktail MountainVery early
1100 GDD needed1129 available before frost
May 25September 27
Tight fit
Why this fit?
Local season fit:
Blacktail Mountain leaves about 29 GDD cushion against the normal Red Lake crop heat estimate.
Best for: cooler-climate watermelon success.
A practical early watermelon that is often chosen specifically for cooler or shorter climates.
Tradeoff: Chosen more for practicality than for maximum fruit 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 Red Lake because they either run past the normal season or leave too little margin before frost.
crimson sweetMid-season
Needs1400 GDD
Red Lake gives1129 GDD
Gap
271 GDD short
1129 GDD available before frost271 more GDD needed
May 25September 27
Runs past season
Why not a main pick?
Local season fit:
crimson sweet usually needs about 271 more GDD than Red Lake provides before frost.
Best for: classic full-size watermelons.
A classic watermelon that usually needs a warmer and steadier season than the quickest small-fruited types.
Tradeoff: Needs a warmer and steadier season than the quickest early types.
moon and starsMid-season
Needs1400 GDD
Red Lake gives1129 GDD
Gap
271 GDD short
1129 GDD available before frost271 more GDD needed
May 25September 27
Runs past season
Why not a main pick?
Local season fit:
moon and stars usually needs about 271 more GDD than Red Lake provides before frost.
Best for: specialty heirloom watermelons.
A specialty heirloom watermelon that is appealing for character and appearance, but more exposed in shorter seasons.
Tradeoff: Chosen for character and appearance more than the safest finish.
bush sugar babyEarly
Needs1250 GDD
Red Lake gives1129 GDD
Gap
121 GDD short
1129 GDD available before frost121 more GDD needed
May 25September 27
Runs past season
Why not a main pick?
Local season fit:
bush sugar baby usually needs about 121 more GDD than Red Lake provides before frost.
Best for: compact early watermelon plants.
A compact early type that is useful when gardeners want a smaller plant without giving up short-season focus.
Tradeoff: More about manageability and fit than maximum vine size or yield.
golden midgetEarly
Needs1250 GDD
Red Lake gives1129 GDD
Gap
121 GDD short
1129 GDD available before frost121 more GDD needed
May 25September 27
Runs past season
Why not a main pick?
Local season fit:
golden midget usually needs about 121 more GDD than Red Lake provides before frost.
Best for: small early watermelon fruit.
A smaller early watermelon that makes sense where fruit size needs to stay realistic.
Tradeoff: More about early finish than big classic watermelon scale.
Variety class
Typical days to maturity
Typical GDD need
Local fit
Very early
75–80
1100
Tight
Early
80–90
1250
Poor fit
Mid-season
90–100
1400
Poor fit
Main risk: The main issue here is usually simple season length: the crop often runs out of time before finishing properly.
How Frost Affects Planting Dates for Watermelons in Red Lake
Red Lake usually has about 125 frost-free days, with a typical last spring frost around May 25 and a typical first fall frost around September 27.
Season extension can improve the odds here, but it works best when paired with the fastest-maturing watermelon varieties rather than slower classes.
Typical last spring frostMay 25
Typical first fall frostSeptember 27
Typical frost-free days125
Minimum safe temperature32°F /
0
°C
Watermelons are generally
frost-tender
and temperatures below about 32°F (
0
°C) can slow growth or damage plants.
Watermelons are much more exposed to frost risk, so the frost dates matter as real planting boundaries rather than rough planning markers.
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.
Watermelons are closer to the limits of the local season in Red Lake before fall frost around September 27, so microclimate plays a bigger role here than it does for easier crops. Local gardens do not all warm and cool at the same pace. 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 watermelons, warmer local sites usually help the crop get established earlier and grow a little more steadily.
Give watermelons a warmer start with protection
If you try watermelons, focus on the supplies that create a warmer start and reduce early-season setbacks.
Start earlier indoors
Long-season crops lose too much time when they start slowly.