Heather’s Gardening Service

Written by Heather Morren

This year, the end of winter felt a little different. Instead of two to three months of unrelenting cold, early February brought us sun, warm weather, and unexpected thawing followed by another huge dump of snow (on top of the ice). Nevertheless, according to the calendar, there are only 19 more days until it is officially spring. I’ll believe it when I see it.

With all these positive changes, you might already be thinking about all of the wonderful things you want to plant in your vegetable garden this year. But, be wary. Spring in Edmonton always has a few tricks up its sleeve.

When to Plant

Historically, the weather in Edmonton tends to stay on the cool side until mid to late May. The average last frost date in Edmonton is around May 15–20, but frosts have been recorded into early June. We have been known to get cold spells that dip below zero and result in snow all the way up to the May Long Weekend. 

Edmonton falls within Zone 3b–4a, which means our growing season is shorter than many other parts of Canada and timing matters for your delicate seedlings.

It is recommended to wait at least until the last spring frost before sowing your seeds, otherwise you risk the soil being too cold for the seeds to germinate. 

Can’t Wait that Long?

“May Long Weekend?” you cry, “That’s almost 3 months away!” I know! I know! It sounds like forever when you’re itching to get planting but there are some things you can do in the meantime. If you have a nice sunny spot in your home, you can start to sow your seeds inside. Many vegetables like herbs, tomatoes, lettuce and peppers can be planted indoors.

Planting kits can be purchased at any local garden centers or even at a Dollar Store. All you need is:

• Seeds
• Soil
• A planting tray or small container
• Labels
• Water
• Light (see Pro Tip below)
• A tray cover helps to keep the plants nice and toasty, as well.

Pro Tip:

Spring sunlight through a window is often not strong enough. Grow lights positioned 2–3 inches above your seedlings for 14–16 hours per day will prevent tall, “leggy” plants.

Seeds, soil, containers and labels ready for planting

What Should I Plant?

Fortunately for gardeners in Edmonton and area, the weather in zone 3/4 is great for growing almost any vegetable. 

Some of the most reliable vegetables for Edmonton gardens:

• Lettuce
• Carrots
• Pea
• Bean
• Onions
• Potatoes
• Beets 
• Kale

Warm-season crops like tomatoes, peppers, cucumbers, and squash grow beautifully here but only if started indoors or planted once the soil has warmed.

Herbs, such as, parsley, cilantro, oregano, basil, dill, rosemary, and thyme also grow well outdoors. See my April 2025 blog article Creating a Thriving Herb Garden for more information.

You may also wish to try your hand at some more challenging crops including pumpkins, watermelon, squash, celery, corn, eggplant, and cauliflower. Just be mindful of their longer maturity dates (90–100+ days).

What you decide to grow really depends on what you and your family and friends want to eat!

When Should I Plant My Seeds?

You may be surprised to learn that Edmonton’s growing season is actually one of the longest in the Canadian Prairies. On average, it ranges from mid May until mid September. That gives us roughly 110–135 frost-free days.

But there is a lot of variability. 

Some plants mature quickly:

• Spinach and lettuce need about 40-45 days 

Others need more time:

• Carrots, peas, beans and cucumbers, need approximately 55-65 days
• Pumpkins, brussel sprouts and some types of squash, take about 90-100 days 

Because our frost-free window can be unpredictable, planning backward from the average last frost date is one of the best strategies for success.

Edmonton Seed Starting Quick Guide

Here’s a simplified timeline for beginners:

Vegetable	Start Indoors	Direct Sow	Transplant Outside
Peppers	Early March	—	After May Long
Tomatoes	Late March	—	After May Long
Broccoli	Early April	—	Mid–Late May
Lettuce	April (optional)	Early May	Mid May
Carrots	—	Early–Mid May	—
Beans	—	Late May	—

For a detailed planting calendar, resources like Old Farmer’s Almanac Planting Calendar and provincial guides from Alberta Agriculture and Forestry can provide crop-specific recommendations.

Common Beginner Mistakes 

Even experienced gardeners get caught by Prairie weather. Here are a few pitfalls to avoid:

• Planting warm crops too early
• Skipping the hardening-off (see note) process
• Starting seeds indoors too soon (leading to weak, leggy plants)
• Overwatering seedlings
• Forgetting about strong wind exposure

Note:

Hardening off means gradually exposing indoor seedlings to outdoor conditions over 7–10 days, which dramatically improves transplant success.

Tomatoes, bell peppers and jalapenos hardening off in my mini greenhouse on my deck.

No Room? Not Enough Sun? Now What?

If you don’t have the space, sun or time, to start your plants indoors, you can still start preparing for the gardening season in early spring:

• Start tidying up by getting rid of old dead growth 
• Add nutrients to the soil, such as tilling in compost
• Decide on the plants you want to grow and where you’d like to plant them. 
• Research what kinds of sunlight, moisture and support your plants will need
• Take time to make sure you have quality seeds and equipment on hand

Raised beds and dark soil warm up faster in spring, which can help extend your season slightly. See my December 2024 blog article Container Gardening for Small Spaces for more tips and tricks. 

Gardening in Edmonton requires patience — but the reward is worth it. With grocery prices continuing to rise and more families looking to grow their own food, starting your vegetable garden is both practical and empowering.

With thoughtful planning and a little protection from those unpredictable spring frosts, your backyard can be bursting with fresh vegetables by mid-summer.

What are you planning to grow this year?

Happy Planting! 

Photos in this article were taken by Heather Morren. Information was sourced from a wide variety of online resources. Please ask, should you wish to see a full list.