Here’s a gardener’s nightmare… you purchase your beautiful flower seeds for the growing season. In the spring, you plant those seeds in the ground. And then you wait for the first little sprouts to pop up. You wait. And you wait. And you wait some more. Eventually, you realize nothing is going to grow.

Why did your brand new seeds fail? Maybe the seeds needed a period of cold in order to sprout. We call this chilling time stratification. It’s basically a process to simulate the natural cycle of seeds in the wild.

What is Seed Stratification…

Many seeds need a time of cooling or dormancy in order to grow. This time of cooling is nature’s way of protecting the seeds from sprouting too early. If the plant drops its seeds in autumn, the seeds will need to survive the cold temperatures until the weather has warmed up enough to allow the plant to grow. But if the seeds sprout immediately, then winter temperatures could kill the baby plants. Many seeds have this built-in mechanism to prevent early germination until the temperatures are warm enough for the plant to survive.

When you purchase seeds, they haven’t gone through the chilling cycle they need in order to germinate. If you plant those seeds without stratifying them, they might not germinate at all or will do so at a lower rate.

It’s best to stratify your seeds to prepare them to break dormancy and grow. With stratification, you’re basically treating your seeds to a cycle of cold in order to prepare them for germinating in the spring.

How to Stratify Your Seeds…

There are several ways to treat your seeds to a winter environment. If you’re already growing the plant in your garden, the easiest technique is to let some seeds drop in the fall and allow them to go through the cold cycle naturally. Once the seeds germinate and grow for a few weeks, you can transplant the baby seedlings to wherever you want them.

When using purchased seeds, you have a few options. Start by checking the back of your seed packet to see if the seed needs this time of cold and note the length of the cold period. Not all seeds need to be stratified. For those that do, they usually need between 4-6 weeks of cold temperatures. Some could use more or less, depending on the plant.

Choose one of the following methods to cold stratify your seeds. Which technique you use will depend on when you purchase your seeds, how much room you have in your refrigerator, and how much time and effort you want to put into this process.

Dry Method

Place the whole seed packet in the coldest part of your refrigerator and just leave it for 4-6 weeks. Be sure that it’s in a place where the seeds will stay dry. Consider putting the packets into a ziplock baggie or a food storage container for safe keeping in your refrigerator.

Pros: This is the simplest method of treating your seeds. It doesn’t take a lot of effort to chill your seeds and you don’t need a lot of space.

Cons: Some seeds benefit from moisture to help soften their outer hull. So by using this method, you might not get as many seeds to germinate.

Wet Method

Some seeds will benefit from moist stratification. To do this, spread your seeds onto one side of a paper towel and then cover the seeds by folding over the towel. Using a spray bottle, moisten the towel with purified water and place in a storage bag. You want the towel moist but not dripping wet. Place the seeds in the refrigerator. Be sure to leave the bag open to allow for air circulation and to help prevent against mold. Periodically check that your paper towel is still moist.

Pros: This wet method helps to speed up the germination process by softening the outer seed hull.

Cons: This process takes up more space in your refrigerator, especially if you have a lot of seeds that need to be stratified. Too much moisture could also cause your seeds to mold if you’re not careful.

Outdoor Method

The third method is to plant your seeds outdoors in late autumn or early winter. Then allow the seeds to go through this period of cold naturally. Plant your seeds in a tray or container and set them in an area that is cold but protected from creatures such as squirrels and rodents. This takes some advanced planning. It works well if you purchase your flower seeds early, but not so well if you wait until late winter to order seeds.

Place these outdoor containers in an area where the temperature does not fluctuate. If you have a warm spell, heat on the container might encourage early sprouting and then a drop in temperature could kill the seedlings. Store these containers in an area that does not get direct sunlight, to help minimize this problem.

Pros: You can do this in the earliest winter months and then forget about the seeds until they germinate.

Cons: The planted seeds need to be exposed to not only the cold but moisture as well. You should occasionally check the containers for moisture and add some as needed. Stratifying outdoors can lead to some losses if critters dig up your seeds.

Seeds That Benefit From Stratification…

Here’s a list of some of the most common seeds that need stratification. While not a complete list, it includes many of the flowers and herbs you might be growing.

Flowers

• Aster
• Bachelor Button
• Bee Balm
• Bells of Ireland
• Black-Eyed Susan
• Columbine
• Coneflower
• Delphinium
• Foxglove
• Heliopsis
• Hollyhocks
• Larkspur
• Lobelia
• Lupine
• Milkweed
• Pansy
• Poppy
• Pincushion Flower
• Primrose
• Violet
• Yarrow

Herbs

• Anise Hyssop
• Catmint
• Chamomile
• Chives
• Hyssop
• Lavender
• Marshmellow
• Mint
• Oregano
• Parsley
• Rosemary
• Sage
• Thyme

Vegetables

• Artichoke
• Asparagus

READ: How to Organize Your Seeds

Other Pre-Treatment Methods for Seeds

There are some seeds that might need a different treatment. These seeds have a hard outer shell that can be difficult to break through. In the natural environment, these hard-shelled seeds are often exposed to moisture and wildlife that can break through or soften the outer hull.

To mimic this natural experience, these seeds might need scarification. This is the practice of scaring the outer seed coating so the germinating plant can break through the hull. The easiest way to do this is to use a nail file or sandpaper to rough up the outside of the seeds. Another option is to soak these seeds for 12-24 hours to soften the hull before planting.

Here are a few plant seeds that benefit from scarification…

• Beans
• Columbine
• Corn
• Garden Peas
• Lupine
• Morning Glory
• Nasturtiums
• Sweet Peas
• Winter Squash

As a new gardener, it took me a few years to figure out why my poppy seeds would never germinate. Once I realized these seeds needed a period of cold, I was able to grow this flower abundantly.

With just a little planning and a time of seed stratification, you can make sure that your new seeds will germinate. You won’t end up with a packet of seeds that refuse to grow. Instead, you can look forward to your most amazing garden ever.