Chaparral Green Thumbs May 2026

Should We Plant in May… or Hold Off a Little Longer?

by Jolene Ottosen
for the Chaparral Green Thumbs

By the time May
rolls around, most Calgary gardeners are more than ready to get planting. The
sun feels warmer, garden centres are open, and the May long weekend looms like
a finish line. For years, that weekend has been treated as the “safe” time to
plant the garden—as long as there isn’t snow on it.

But if you’ve
gardened here long enough, you know the truth: May can still be tricky.
Some plants should already be in the ground by now, others are just right, and
a few really shouldn’t be planted yet—even on the May long weekend. Some years,
May long is perfect. Other years, it’s too soon, with frost, cold soil, or even
snow still in the forecast.

Rather than
planting everything at once, it helps to think about:

·       Are you
planting seeds or seedlings?

·       What
vegetables are you growing?

·       How
much protection or attention are you willing to give them?

When I was growing
up on the farm, the whole garden went in as seeds on one day. It was watered
well early on and then mostly left to fend for itself. That approach still
works for many vegetables. But some crops benefit from being started earlier
indoors or planted as transplants once conditions are right.

The following
chart is one I’ve shared before, and it remains a solid general reference for
vegetable planting in the Calgary area.

Calgary Vegetable
Seeding and Planting Chart

Adapted from
Calgary Garden Coach (2009), adjusted for current conditions.

Direct Seeding in
May

By May, many
cool-season crops are happy to be direct seeded, provided the soil isn’t
waterlogged or frozen. Root crops, greens, peas, and potatoes all do well if
planted early to mid-May.

If you’re planting
later than ideal or want quicker results, soaking seeds for 12 to 24 hours can
help speed germination. Larger seeds benefit the most, while tiny seeds can be
soaked on damp paper towel or planted using a squeeze bottle method. Just
remember—better germination often means more thinning later.

Transplanting
Seedlings

May is prime
transplanting time—but timing and protection still matter.

Seedlings that
have been grown indoors or in greenhouses need time to adjust to wind, sun, and
Calgary’s temperature swings. Hardening off is still essential, even in mid‑May.

A few reminders:

·        
Let plants dry slightly between waterings
before planting out.

·        
Start them outdoors in shade, gradually
increasing sun over 7 to 14 days.

·        
Bring them in at night if temperatures
dip.

·        
Plant on a cloudy day or late in the
afternoon.

·        
Be ready to cover if frost threatens—row
cover, buckets, cloches, or even old towels work well.

Even around May
long weekend, tomatoes, squash, cucumbers, and peppers often need protection.
Some years, planting them out that early leads to setbacks instead of a head
start.

So, Is May the
Right Time to Plant?

Yes—but not all at
once.

Early May is ideal
for hardy, cool-weather crops. Mid to late May works well for transplants that
have been hardened off. May long weekend is a guideline, not a guarantee. Some
years it’s perfect; other years it’s still too soon for tender plants without
protection. The best approach is to plant based on what each crop needs—not the
date on the calendar. If you’re willing to cover and babysit, you can push
things earlier. If not, patience often pays off. As long as you enjoy the
process—and the harvest—you’re doing it right.

If you are
interested in joining us in the garden next season, we would love to hear from
you! Please email us at [email protected].

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