When to Plant Melons in St. John's

Can Melons Mature in St. John's?

Growing degree days measure how much useful warmth typically accumulates during the season. For melons, this helps estimate whether local heat accumulation is usually enough for the crop to reach maturity on time.

From the usual planting window, St. John's typically provides about 1066 growing degree days for melons. With a typical crop target of 1200, that leaves a heat margin of -134. That narrow heat margin means small delays or slower varieties can quickly reduce the odds of timely maturity.

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.

How Different Melon Varieties Affect Results

In St. John's, very early and early melon 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:

• Minnesota Midget — one of the best-known short-season muskmelons where getting any ripe melon is the first priority
• Sweet Granite — an early melon that makes sense when the season is too tight for larger standard muskmelons

Main risk: Delays in planting or slower melon varieties can quickly push maturity past fall frost.

How Frost Affects Planting Dates for Melons in St. John's

St. John's usually has about 143 frost-free days, with a typical last spring frost around May 28 and a typical first fall frost around October 18.

Season extension can improve the odds here, but it works best when paired with the fastest-maturing melon varieties rather than slower classes.

Melons are generally frost-tender and temperatures below about 32°F ( 0 °C) can slow growth or damage plants.

Melons are much more exposed to frost risk, so the frost dates matter as real planting boundaries rather than rough planning markers.

The most common problem is running short on season. Late planting, slower varieties, and cooler exposed sites can turn a possible crop into a disappointing one.

In St. John's, the season is usually supportive for melons, though warmer sites still help with how comfortably they finish before fall frost around October 18. 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 melons, warmer local sites usually help the crop get established earlier and grow a little more steadily.