Stratifying Seeds Naturally Outside in Fall
Many Tree Seeds, along with some perennial flowers and herbs, require something called stratification. Nature is amazing and these seeds come equipped with a temperature-based internal clock which tells the seed when to wake up and start growing. It’s stratification that gets this clock ticking!
Stratification breaks a seed’s dormancy and stimulates a seed’s germination process; encouraging it to sprout at the proper time of year. Some seeds require cold stratification & some require both warm & cold stratification. In nature, these processes happen naturally with the turning of the seasons.
Some popular seeds that can be easily planted outside in the Fall include lavender, milkweed, coneflowers, maples and many nut trees.
Flowers & Herbs
Many herbaceous plants can be planted right in your garden. So simple! Prepare the site as you would in Spring and plant the seeds to the appropriate depth. Keep your seedlings weeded and thin them for proper spacing in Springtime. Pay attention to any special requirements listed on the seed packets and otherwise, you’re ready to plant!
Trees & Shrubs
These larger and longer lived plants can also be planted in their permanent location, but please consider their eventual size. If you know where you want to plant them, follow the seed’s specific growing instructions, and plant a few seeds in your chosen location; thinning to the strongest plant.
Planting in a Nursery Bed
Nursery Beds are space efficient and great if you’re planting a large quantity of seeds. Think of a nursery bed as a small veggie garden. Plant your tree seeds in rows and thin plants to a spacing of 4-6 inches the following year. Young plants can remain in a nursery bed for 1-2 years.
Take specific soil & sunlight requirements into account when setting up your nursery bed.
Planting in Pots
If you love planting seeds but don’t always know where you’re going to plant them long term, this is the most flexible option!
Fill your pots (minimum 1 gallon) with garden soil and plant your seeds at the recommended depth. Dig a trench deep enough to accommodate the pots and bury them up to the rim. This will insulate them over the Winter and regulate moisture over the Summer, just as if they were planted directly in the ground. Young plants can remain in these pots for 1-2 years.
Timing
For seeds that require cold stratification, planting is best done in late Fall; after the first frost but before the ground completely freezes. This timing allows seeds to experience the cold conditions they need to break dormancy over the Winter. Seeds that require both warm and cold Stratification, should be planted outdoors in mid-late Summer according to their required number of warm stratification days.
Adding Mulch to Maintain Moisture
After planting, apply a thin layer of organic mulch, such as straw or shredded leaves. This layer acts as a blanket; helping to protect the seeds from harsh Winter temperatures and heavy rains.
*Some seeds require light for germination. For these you can forego mulching, or ideally, mulch and then uncover the seeds in the Spring.
Protection from Pests
To deter birds, rodents, and other animals from digging up and running off with your seeds, cover the planted area with hardware cloth. It is important to remove the hardware cloth as your plants get bigger or they will grow through it and get stuck.
What to Expect in Spring
Germination
As the weather warms, seeds that were planted in the Fall will start sprouting! If mulched, gently pull the mulch back from the stems of emerging plants. Some plants like hickory and sugar maple, will produce leaves early on. Others, like pawpaw, spend their first few months developing roots underground and won’t send up stems and leaves until later on in the Summer.
Watering
It is important to keep the soil consistently moist to support the seedlings' growth. Soil should be damp but well-drained to ensure healthy young plants. If growing in pots, you’ll need to pay extra attention to this and water accordingly.
Working with Nature’s natural rhythms is the best and easiest way to garden and now you can use these principles for starting your seeds this Fall. Have fun!