How to Cold Stratify Snapdragon Seeds
Snapdragons are excellent cool-weather perennials with the most enchanting flower spikes. They are great for the cutting garden or any sunny spot in the yard. Gardening expert Melissa Strauss discusses cold stratifying as it relates to these wonderful plants.
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A few years back, I started growing snapdragons in my cutting garden, and I’ve never looked back. These cool weather blooming perennials are one of the more prolific producers in my yard. Not to mention, they are stunning in floral arrangements.
If you’ve never grown these plants, I highly recommend it. They are easy to care for, and the bumblebees adore them. I occasionally find those fuzzy little pollinators asleep inside a snapdragon blossom. My kids also love them for their whimsical snapping jaws.
Snapdragons are easy to grow from seeds, but they may require cold stratification— also known as cold exposure—in certain climates. They germinate quickly and transplant easily. They come in a wide array of colors, some tall and elegant, others will stay shrubby and close to the ground.
They are perennial in Zones 7-10, sometimes as far north as Zone 5, but you can grow them as annuals in cooler regions. If you can keep them cool through the summer, you’ll have a second blooming period in the fall. Let’s talk about cold stratification and whether it’s an important factor in your snapdragon’s seed success.
What is Cold Stratification?
If you’ve been growing flowers from seeds for very long, you probably know the answer to this question. If not, it’s an important factor in the successful germination of many plants. Warm climate plants typically don’t require it, but it’s necessary for many cool climate plants, for good reason.
Plants typically drop their seeds in the fall. If you leave some flowers intact and allow them to dry out, many plants are excellent for self-seeding. For plants that are native to cold climates, it’s important that they don’t germinate until the spring. Otherwise, cold temperatures would kill off the young plants before they have a chance to bloom and go to seed.
As a result, many of the seeds that come from these plants have a hard outer shell that has to break down in order to allow water in. Water is what initiates the germination process, so keeping it out keeps them dormant. These plants have adapted to the weather in a way that ensures their survival.
As the winter weather cools and warms, freezing and thawing, the hard outer shell begins to break down. By the time spring comes around, it’s possible for water to get in, and they sprout at a time when they will survive. This is a good argument for fall planting, but that’s not always convenient, and in some cases, the seeds don’t take well to direct sowing.
Is it Necessary for Snapdragons?
The answer is yes and no. Cold stratification is a necessity for some seeds. Those with thick, hard casings are particularly hard to germinate without this process. But what about snapdragons?
Snapdragon seeds are very tiny. They are similar to poppy seeds but slightly smaller. That means that their outer shell can’t be all that thick. When it comes to these flowering perennials, cold stratification is likely to increase your germination rate. Neglecting to do it won’t stop some seeds, though.
In my experience, cold stratification is not expressly necessary for snapdragons. I start my seeds in the fall and put them in the ground before the first frost. I am in Zone 9, and while we get some cold fronts that can include a hard freeze or two, my snapdragons make it through with flying colors.
This makes cold stratification optional for this particular plant. If you have the time and inclination, it may increase your germination rate. However, you’re almost certainly going to have plenty that sprout without it.
How to Do It
There are two ways to carry out this process, and they both have benefits, but for this plant, one is certainly more effective than the other. Let’s take a look.
Naturally
To allow nature to do its own stratifying saves a lot of time and effort. If you are growing seeds that don’t mind direct sowing in the garden, this works quite well. There are plenty of plants that follow this rule.
Some examples of plants that work well this way are: sweet peas, as they prefer no root disturbance, so direct sowing is best. Many bulbs are great for fall planting. They need that dose of cold weather as well. Many native plants will also perform well under these circumstances.
When it comes to snapdragons, it’s not exactly ideal. The reason is that they take a long time to grow and set down roots. They need light to germinate, so they need exposure rather than having soil to hold them in place. Add in the time of cold exposure and dormancy, and you’re unlikely to see many of them stay in place all winter.
For this reason, it is more effective to start them indoors in a controlled environment. While controlled stratification will improve germination, you’ll have more success starting unstratified seeds indoors than those directly sown in the fall.
Alternately, if your soil is workable in early spring, several weeks ahead of your last frost date, you can plant them outdoors at this time to expose them to some cold. However, the same issue is true at this time, too. The tiny seeds are hard to keep in place long enough for them to germinate and firmly take root.
Artificially
That brings us to the most effective practice when it comes to the preparation and germination of snapdragons. You can artificially stratify snapdragons in your home, improving your chances of a high rate of success.
There are two types of artificial stratification, they are dry and moist. Snapdragons prefer moist cold stratification. The refrigerator is cold enough to accomplish this task. You’ll also need a watertight container or sealable bag and a couple of paper towels or substrate.
Moisten the paper towels or the growing medium, and sprinkle your seeds on top. If you’re using a paper towel, fold it over top of them so they’re surrounded by moisture on all sides. Fold it as many times as necessary to fit in your container or bag. Place your moist towel or growing media in the container and seal it up.
This plant doesn’t require a long period of cold. A few days to a week or two is plenty long enough. When you take them out, surface sow them or spread your substrate on a moist, high-quality starting mix and expose them to light.
Try to be patient about waiting for them to germinate. It typically takes one to two weeks for these to sprout. It can take longer if the soil is too cold. They germinate best at a temperature of 70-75°F (12-24°C). If you keep your home cooler than this, consider investing in a heating mat. These warm the soil and speed germination.
Popular Varieties
Whether you choose to cold stratify or not, here are some of my favorite snapdragon seed varieties for the cutting garden and beyond!
‘Orange Wonder ’
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common name ‘Orange Wonder ’ |
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botanical name Antirrhinum majus ‘Orange Wonder’ |
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sun requirements Full sun to partial shade |
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height 30”-36” |
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hardiness zones 5-11 |
This tall variety is perfect for cut arrangements. At up to three feet tall, they are also great mid-ground plants for your beds. Their stems are substantial and hold upright nicely. Some with thinner stems can tend to bend over when all the flowers bloom. ‘Orange Wonder’ has gorgeous apricot and orange flowers with a sweet pink glow at the bases.
‘Night and Day’
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common name ‘Night and Day’ |
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botanical name Antirrhinum majus ‘Night and Day’ |
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sun requirements Full sun to partial shade |
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height 18” |
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hardiness zones 5-11 |
‘Night and Day’ is a dramatic variety that I am growing for the first time this year. The fluffy blooms are brilliant scarlet, with a pure white throat. The combination is high-contrast and eye-catching. In cool weather, the stems and foliage of this variety turn deep purple. This is a true statement-maker. They are medium height, and still nice as cut flowers.
‘Madame Butterfly Bronze’
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common name ‘Madame Butterfly Bronze’ |
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botanical name Antirrhinum majus ‘Madame Butterfly Bronze’ |
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sun requirements Full sun to partial shade |
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height 31”-40” |
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hardiness zones 4-9 |
If you’ve never seen a double snapdragon, ‘Madame Butterfly Bronze’ is sure to elicit admiration. This extra-tall variety can grow nearly four feet tall and has strong stems. It’s another great choice for the cutting bed. This All-American Selections winner has a similar color to ‘Orange Wonder’ but with darker, bronzed undertones instead of pink. It’s spectacular.
‘Twinny Peach™’
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common name ‘Twinny Peach™’ |
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botanical name Antirrhinum majus ‘Twinny Peach™’ |
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sun requirements Full sun to partial shade |
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height 12” |
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hardiness zones 4-9 |
Another double-flowered variety, ‘Twinny Peach’ has a soft, delicate appearance with heavily ruffled petals. The blooms open peach initially, but as they age, they turn yellow. Because they bloom from bottom to top, this creates a stunning ombre effect with colors reminiscent of a sunset. This is a compact variety, growing only one foot tall. It makes a glorious border, but it is less suitable as a cut flower.
