Growing Snapdragons from Seed in Canada: A Complete Guide

Growing Snapdragons from Seed in Canada: A Complete Guide

Customer photo credit: Amber, Camber ON

Snapdragons (Antirrhinum majus) are one of the best flowers to grow from seed in Canada. Unlike many popular annual flowers, snapdragons actually prefer cooler weather, tolerate light frosts once established, and can produce beautiful flowers from late spring through fall.

They're also one of our favourite flowers for bouquets. Tall varieties produce long, elegant stems covered with colourful blooms, while shorter varieties are wonderful additions to flower beds and containers.

The secret to successfully growing snapdragons from seed in Canada is timing. Snapdragons are relatively slow growing and perform best when they have plenty of time to establish before hot summer weather arrives.

There is also another consideration that many gardeners don't know about: snapdragon varieties are often classified as Group I, II, III or IV. Choosing the right group for your growing season can make a noticeable difference in how well your plants perform.

What Do Snapdragon Groups I, II, III and IV Mean?

If you've shopped for professional or cut-flower snapdragon seeds, you may have noticed varieties labelled Group I, Group II, Group III or Group IV.

These numbers don't indicate quality or plant height.

Instead, snapdragon groups describe the growing conditions—particularly temperature, day length and light levels—in which a variety performs best.

As the group number increases, varieties are generally better adapted to progressively longer days, higher light levels and warmer growing conditions.

Group I Snapdragons – Cool Season

Group I snapdragons are adapted to cool temperatures, shorter days and relatively low light levels.

They are commonly used for winter greenhouse production and very early spring crops. In Canada, Group I varieties can also be useful for very early spring or late-season production, especially when grown under protection.

Circle Farms varieties include:

Best for: Greenhouses, very early spring and late fall.

Group II Snapdragons – Cool to Moderate Season

Group II snapdragons grow well as days become longer and light levels increase, while temperatures remain relatively cool.

That makes Group II varieties an excellent choice for Canadian spring gardens.

Start them early indoors and transplant them outside while temperatures are still cool. This gives plants plenty of time to establish and begin producing flowers before the hottest part of summer.

Circle Farms Group II varieties include:

Best for: Spring through early summer in much of Canada.

Group III Snapdragons – Moderate to Warm Season

Group III varieties are adapted to longer days, brighter light and warmer temperatures than Groups I and II.

This can make them particularly useful in Canada because our northern latitude gives us remarkably long summer days.

Group III snapdragons are excellent candidates for late spring and summer flowering. Depending on your climate, established plants may also produce another flush of blooms when temperatures cool toward fall.

Circle Farms varieties that fall into the Group III growing window include:

Best for: Late spring and summer flowering.

Group IV Snapdragons – Warm Season

Group IV snapdragons are bred for the longest days, highest light levels and warmest growing conditions.

They are generally used for summer production.

Keep in mind that even Group IV snapdragons are still snapdragons. They are fundamentally cool-season flowers, so prolonged periods of extreme heat can reduce flower quality and slow production.

Circle Farms varieties suited to the Group IV/main-season growing window include:

Best for: Summer flowering and warmer Canadian growing regions.

Which Snapdragon Group Is Best for Canada?

For many Canadian gardeners, Groups II and III are particularly useful.

Gardeners in colder areas of Alberta, Saskatchewan, Manitoba and other regions with short growing seasons can start Group II varieties indoors for early flowers and follow them with Group III varieties as summer approaches.

In warmer regions, such as southern Ontario and coastal British Columbia, gardeners can experiment with Groups II, III and IV to extend the flowering season.

You can also succession plant different groups.

Think of the snapdragon groups as a seasonal relay race: one group performs best during cooler spring conditions and another takes over as the days become longer and warmer.

For Canadian gardeners who simply want a dependable place to begin, Group II and II–III varieties are an excellent choice.

When to Start Snapdragon Seeds in Canada

For most Canadian gardens, start snapdragon seeds indoors approximately 8–10 weeks before your average last frost date.

Gardeners who want particularly early flowers can start them even earlier, provided they have good grow lights and enough space to keep the seedlings healthy indoors.

This is one crop you don't want to start too late.

Snapdragons thrive in cool spring conditions. Starting early allows plants to develop good roots and then take advantage of those cool temperatures once transplanted outside.

Unlike heat-loving annuals such as zinnias, snapdragons don't need to wait for hot summer weather before going into the garden.

Once properly hardened off, established snapdragon seedlings can tolerate chilly conditions and light frost.

How to Start Snapdragon Seeds Indoors

Snapdragon seeds are extremely small, so don't be alarmed when you open the packet. You haven't been shortchanged—they really are that tiny!

Before starting your snapdragons, we recommend a brief cold stratification period. This involves placing the seeds in the fridge for 7 - 10 days. As an extra step, and for best germination success, we recommend placing the seeds in a moist paper towel and storing in a ziplock bag or container inside the fridge for 7 - 10 days. 

Remove the paper towel from the fridge and allow to dry on the counter. Then fill trays or containers with a fine-quality seed-starting mix and moisten the mix before planting.

Sprinkle the seeds over the surface and gently press them into the growing medium.

Do not bury snapdragon seeds deeply. They should be surface sown or covered only very lightly because light helps with germination.

Keep the seed-starting mixture consistently moist but never soggy. Bottom watering is particularly helpful because pouring water over the surface can dislodge the tiny seeds.

Snapdragons generally germinate in approximately 7–14 days at around 21–24°C (70–75°F).

Once germination occurs, good light becomes extremely important.

Do Snapdragon Seeds Need Cold Stratification?

Technically, snapdragon seeds do not absolutely require cold stratification to germinate. However, at Circle Farms, we strongly recommend cold stratifying snapdragon seeds before planting.

Cold stratification exposes seeds to a period of cold conditions before sowing. While snapdragons may germinate without this treatment, we have found that cold stratification can help improve germination success and encourage more consistent, uniform germination.

For this reason, we recommend cold stratification as a standard step when starting our snapdragon seeds. Because germination can be less predictable when this step is skipped, we cannot guarantee successful germination if the seeds have not been cold stratified before sowing.

Fortunately, snapdragons don't require a complicated or lengthy stratification process. A short period in the refrigerator is all that's needed.

How to Cold Stratify Snapdragon Seeds

There are two easy methods you can use to cold stratify snapdragon seeds.

Method 1: Refrigerate the Dry Seeds

This is the easiest method and the one we recommend for most gardeners.

Place the seed packet or dry seeds inside a sealed container or bag and put them in the refrigerator for approximately 1–2 weeks before planting.

After the chilling period, remove the seeds and sow them normally on the surface of your moistened seed-starting mix.

Do not freeze the seeds. The refrigerator provides the cool temperatures needed for this treatment without exposing the seeds to freezing conditions.

Method 2: Moist Cold Stratification

Snapdragon seeds can also be cold stratified using a moist medium.

Place the seeds on a slightly damp paper towel inside a sealed container or plastic bag. Refrigerate them for approximately 1–2 weeks.

The paper towel should be lightly damp, not soaking wet. Excess moisture can encourage mould or cause other problems.

After the chilling period, carefully transfer the seeds onto the surface of your seed-starting mix.

Because snapdragon seeds are extremely small, they can be difficult to remove from a damp paper towel. For this reason, we generally recommend the dry refrigeration method—it is much simpler and makes those tiny seeds considerably easier to handle.

Whichever method you choose, plan ahead and build the cold-stratification period into your seed-starting schedule. It's a small extra step that we strongly recommend for the best chance of successful, even germination.

Growing Snapdragon Seedlings

Once your seedlings emerge, give them plenty of light.

A sunny window may not provide enough light during a Canadian winter or early spring. Grow lights generally produce stronger, stockier seedlings.

Snapdragons also don't need tropical temperatures once they've germinated. Cooler growing conditions help encourage compact, sturdy growth.

Good airflow is equally important.

Avoid constantly saturated growing medium and overcrowded seedlings. Both can contribute to damping off and other fungal problems.

Once seedlings develop true leaves and are large enough to handle, they can be transplanted into larger cells or small pots if necessary.

Should You Pinch Snapdragons?

Pinching encourages snapdragons to branch.

Once plants are established, removing the central growing tip encourages several side shoots to develop. Instead of producing one primary flower stem, the plant can produce multiple flowering stems.

For home gardeners and cutting gardens, this can substantially increase the number of flowers available for bouquets.

There is a trade-off.

Pinching generally delays flowering somewhat, and the resulting stems may not be quite as large as the first central stem of an unpinched plant.

If you want the earliest possible flowers, consider leaving some plants unpinched and pinching others.

You'll get early flowers from the unpinched plants followed by a larger number of stems from the pinched plants.

Transplanting Snapdragons Outside

One of the great advantages of growing snapdragons in Canada is that you don't have to wait for summer temperatures before planting them outdoors.

Begin hardening seedlings off gradually by exposing them to outdoor conditions for increasing amounts of time.

Once hardened off, snapdragons can be planted outside while temperatures are still cool.

Choose a location with full sun to partial shade and fertile, well-drained soil.

Garden plants are commonly spaced approximately 15–30 cm (6–12 inches) apart, depending on the variety and desired effect.

Cut-flower growers often plant snapdragons closer together. The competition encourages taller, straighter stems with less branching.

Tall varieties may also require support. Flower netting stretched horizontally above the plants is particularly useful.

Growing Snapdragons for Cut Flowers

If your goal is bouquets, choose tall varieties specifically bred for cut-flower production.

Snapdragons make exceptional cut flowers because their tall spikes add vertical interest to arrangements and contrast beautifully with rounder flowers such as zinnias, dahlias and asters.

Harvest snapdragons when the bottom few flowers on the spike have opened but the flowers toward the top remain in bud.

Regular harvesting encourages plants to continue producing additional stems.

For the straightest stems, provide support netting before plants become tall enough to flop over.

Keeping Snapdragons Blooming All Summer

Snapdragons naturally perform best during cooler weather.

Plants may flower heavily in late spring and early summer before slowing during periods of intense summer heat.

Don't necessarily pull them out.

Keep the plants watered and continue deadheading or harvesting the flowers. When cooler late-summer and fall temperatures arrive, plants will often begin producing beautiful flowers again.

This ability to thrive during Canada's cool spring and fall weather is one of the reasons snapdragons are such a worthwhile addition to a cutting garden.


Troubleshooting Snapdragon Problems

Snapdragon Seeds Aren't Germinating

The seeds may have been buried too deeply, allowed to dry out or kept excessively wet.

Surface sow the seeds, maintain consistent moisture and provide appropriate light.

If you did not cold stratify your seeds before planting, this may also contribute to poor or uneven germination. At Circle Farms, we strongly recommend cold stratifying snapdragon seeds for 1–2 weeks before sowing.

Snapdragon Seedlings Are Tall and Floppy

Insufficient light is usually the culprit.

Move seedlings closer to your grow lights or increase the amount of light they receive.

Growing seedlings at cooler temperatures after germination can also encourage sturdier plants.

Seedlings Suddenly Collapse

This is often damping off, a fungal problem that commonly affects young seedlings.

Improve airflow, avoid overcrowding and don't keep the growing medium constantly saturated.

Bottom watering can also help keep the stems and foliage dry.

Snapdragon Leaves Are Turning Yellow

Yellow leaves can be caused by several things, including excessive watering, nutrient deficiencies or poor drainage.

Check moisture levels first.

Once plants are actively growing, a light application of balanced fertilizer may help if your seed-starting medium contains very little nutrition.

Snapdragon Plants Are Short With Small Flowers

The variety may be growing outside its ideal seasonal conditions.

A cool-season Group I or II snapdragon grown during hot summer weather may not produce the same tall, strong stems that it would during spring.

For summer production, look for Group III, III–IV or IV varieties.

Snapdragons Stop Flowering in Summer

Heat is often responsible.

Continue watering, harvesting and deadheading the plants. Once cooler temperatures return, healthy plants may begin flowering heavily again.

The Best Snapdragon Varieties for Canadian Gardens

There isn't one perfect snapdragon for every Canadian garden. Instead, choose varieties according to when you want them to flower.

For early-season production, look for Group I, I–II and II varieties.

For spring into early summer, Group II and II–III varieties are excellent choices.

For warmer and longer summer days, consider Group III and IV varieties.

You can also grow varieties that aren't commonly marketed by group. Popular garden and cut-flower series such as Madame Butterfly, Chantilly and Rocket provide different flower forms, colours and growth habits.

Growing several types is one of the easiest ways to discover which perform best in your particular Canadian climate.

Final Tips for Growing Snapdragons from Seed in Canada

If there's one secret to growing beautiful snapdragons in Canada, it's this: don't treat them like heat-loving summer annuals.

Start your seeds early.

Give the seedlings plenty of light.

Cold stratify your seeds before sowing.

Get the plants outside while spring temperatures are still cool.

And when possible, choose a snapdragon group suited to the season in which you want it to flower.

For many Canadian gardeners, Group II and Group III snapdragons are an excellent place to start. More experienced growers can combine several groups to extend their harvest from cool spring weather through summer and into fall.

Snapdragons take a little patience when they're tiny seedlings, but they're well worth the wait. Their tall, colourful flowers are beautiful in the garden, irresistible to pollinators and wonderful for bouquets.

And unlike many flowers we grow in Canada, snapdragons don't merely tolerate our chilly spring weather—they actually rather like it.

Shop Snapdragon Seeds in Canada

Looking for varieties to grow in your own garden?

Circle Farms carries a selection of snapdragon seeds for Canadian gardeners, including varieties suitable for cut flowers, bouquets, flower beds and containers.

Explore our Snapdragon Seed collection to compare colours, flower forms and growing groups and find the right varieties for your garden.

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