What Does It Mean To Cold Stratify A Seed?

by | Last updated on January 24, 2024

, , , ,

Cold stratification is

the process of subjecting seeds to both cold and moist conditions

. Seeds of many trees, shrubs and perennials require these conditions before germination will ensue.

How do you cold stratify seeds?

  1. Place a 1/4 cup of sand (or more) in a mixing bowl. …
  2. Add your desired seed amount to the sand. …
  3. Place sand/seed mixture in a ziploc bag and seal.
  4. Label the variety and date clearly on the bag.
  5. Place in the refrigerator for 1 month before planting.

How cold does it have to be to stratify seeds?

Dry stratification is a seed pre-treatment in which the seed is subjected to cold temperatures of

32 ̊F or lower

, for a period of a month or longer. This simple treatment of keeping the seeds in cold, dry storage helps increase germination rates by immitating a natural winter dormant period.

Why do seeds need cold stratification?

You can tell seeds that need a cold period before germinating because they

have hard bony coats that are impervious to water

. Having such a tough shell ensures that germination occurs only when conditions are right. … So time and temperature are the keys necessary to unlock germination for many seeds.

How do you cold stratify seeds indoors?

  1. Step 1: Wet a paper towel and lay on a flat surface. …
  2. Step 2: Sprinkle 10-20 milkweed seeds on the paper towel. …
  3. Step 3: Fold the paper towel into quarters.
  4. ​Step 4: Place the paper towel into the bag, seal, and label. …
  5. Step 5: Place in the refrigerator for 30-60 days. …
  6. Step 1: Place seeds in trays.

What is the best way to stratify seeds?

The most dependable way to stratify seeds is in

a moist medium, wrapped in plastic in the refrigerator

. Larger seeds tend to do well in a bit of moistened peat or sand, placed into a plastic bag. Smaller seeds can be distributed onto moist paper towels. The trick is to keep them moist, but not sopping wet.

Can I stratify seeds in the freezer?

Improper freezing can kill some seeds, but other seeds may be less fussy. In fact, many wildflower, tree and shrub seeds actually require a

cold period

, or stratification, before they will germinate. … This period of stratification can easily be simulated in a freezer.

Do seeds need light to germinate?

Some seeds don’t need light to break through their seed casings and sprout.

Most seeds germinate best with controlled amounts of UV generation

, but there are seeds that germinate in the absence of light. Furthermore, there are plants that get enough just light in highly shady areas of a garden or even in darkness.

Do all seeds need cold stratification?

So, when is cold stratification of seeds necessary?

Cold treatment for seeds is necessary for plants or trees that require time in the ground over winter in order to germinate

. … Check the seeds after 10 days to see if they are sprouting, as some seeds may require a longer period of cold and wet conditions.

What happens if seeds freeze?


Freezing seeds does not harm them

, and can greatly extend their lifespan if done properly. All seed banks freeze their seeds intended for long term storage! Humidity is a greater concern with freezing, as a blast of warm humid air on frozen seeds can damage them.

Do forget me not seeds need cold stratification?

Growing Forget-Me-Not From Seed

Seed Treatment:

None required

, though cold stratification is recommended for spring-sown seeds. … As always when growing forget-me-not from seed, be sure to keep your seeds moist while they’re germinating, and until your seedlings are established.

What must be done before sowing the seeds in the seed box?


Fertilized garden soil or commercially available potting mixes also work

. Once the boxes are filled, water them thoroughly and let the excess water drain out. When you plant the seeds, the soil should be moist but not soaking wet. When ready, plant the seeds according to the instructions on the seed packet.

How do you speed up cold stratification?


Freezing and thawing

: Freezing and thawing of the seeds seems to speed up the stratification process compared to storing them at a constant refrigerator temperature.

Can seeds germinate in the refrigerator?

Refrigeration usually works well, but you

must make sure the seeds are moist

! *Warm stratification means to place seeds in contact with warm, moist soil (usually to simulate the end of summer and usually followed by cold stratification).

James Park
Author
James Park
Dr. James Park is a medical doctor and health expert with a focus on disease prevention and wellness. He has written several publications on nutrition and fitness, and has been featured in various health magazines. Dr. Park's evidence-based approach to health will help you make informed decisions about your well-being.