Stratification uses temperature to break dormancy, while scarification uses mechanical, chemical, or thermal means to break down a hard seed coat that is impervious to water. Stratification is the process in which a seed is exposed to moist, cold, or warm conditions in order to break dormancy.
Scarification of seed is the process of scratching the seed coat to allow moisture to enter the seed itself. If a seed requires scarification, gently scratch the seed with a sandpaper block prior to planting outdoors, or prior to moist stratification. Many members of the pea family (legumes) benefit from scarification.
What are the Similarities Between Stratification and Scarification? Stratification and scarification are two types of mechanisms that help to overcome seed dormancy. Both methods stimulate seed germination.
Seed coat (external dormancy) results from a seed's hard seed coat that is impervious to water and gases. The seed will not germinate until the seed coat is altered physically. Any process of breaking, scratching, or mechanically altering the seed coat to make it permeable to water and gases is known as scarification.
Scarification methods such as heat, freeze-thaw, mechanical and acid scarification are useful tools to soften hard seeds, improve germination and enhance seedling establishment.
Stratification uses temperature to break dormancy, while scarification uses mechanical, chemical, or thermal means to break down a hard seed coat that is impervious to water. Stratification is the process in which a seed is exposed to moist, cold, or warm conditions in order to break dormancy.
If you're going to stratify seeds, be sure you can keep the seeds in the refrigerator for however long they need to chill. Soak seeds in water for 12 to 24 hours. Remove the seeds from the water and lay them on a soft cloth. Mix a medium of equal parts of sand and peat moss.
There are six methods of stratification: cold water soaking, refrigeration, fall sowing, winter solstice sowing, outdoor treatment, and snow planting. Time to stratify seeds varies by species, though in most cases storing damp seeds at 39 to 40°F (4 to 5°C) for two to three months is sufficient.
Stratification occurs naturally when seeds are sown outdoors through the cold winter. It is a survival mechanism so the seed does not prematurely germinate. Many plants require a period of cold temperatures to break their dormancy cycle with woody plants and herbaceous perennials being some of the more common species.
Stratification is accomplished by placing seeds in moist planting medium in a cold environment for a period of time (two weeks to three months). Seeds require moisture, cold and oxygen. In general, this period of time allows an undeveloped embryo to mature.
The seeds of most annual garden flowers and vegetables require no stratification. However, many trees, shrubs, perennials, and wildflowers will only germinate after their seeds are stratified.
Sociologists have distinguished between two systems of stratification: closed and open.
For the most successful (and quickest) germination of these seeds, you can scarify and soak the seeds before planting. Seed Scarification: nicking, breaking, softening, or otherwise weakening of the seed coating meant to speed up germination.
COLD STRATIFY SEEDS: PLANTING
The time you need to keep your seeds in the refrigerator depends on the variety, but 4-5 weeks should be a sufficient amount of time for most seed varieties. Once there's no more chance of frost in your area, take your seeds out of the fridge and spread seed on bare soil as normal.
Mold also seems to be less of a issue at temperatures close to, but not below freezing. Another tip is to not start stratification too early, if the seeds require 30 days of cold stratification, plan to stratify for 30 days, because if you stratify for 60 days that's a extra 30 days where they might get moldy.
Cold Dry Stratification
To dry stratify seeds: Place seeds or seed packages in a ziplock bag or fridge-friendly container. Store the container in the fridge or freezer for 30-60 days, or as required by your seeds.
Stratification is the process of giving your seeds a period of 'cold' to prepare them for better germination. If you dont stratify seeds, they can still germinate but the rate is often much lower and they can actually take 2 or 3 times longer to germinate.
Mix your seeds into the medium. A ratio of about one part seed to three parts sand (medium) is a good guide. Place into a labeled, dated Ziploc bag. Place the bag into the refrigerator–in the back or at the bottom where it's coldest, but not in the freezer!
Warm stratification means keeping the seed/sand mix at about room temperature, 60-70°F or 15-21°C; cold means keeping the mix at about 40°F (5°C) – a domestic fridge is ideal for small quantities.
Freezing and thawing of the seeds seems to speed up the stratification process compared to storing them at a constant refrigerator temperature.
Perennial Seeds That Do Not Require Cold Stratification
Other easier to grow perennials not requiring cold stratification are coneflower (Echinacea purpurea), spotted bee balm (Monarda punctata) and wild bergamot (Monarda fistulosa). I tried these last year and all grew well. The coneflower was the most gratifying.
They observed that plants that had acetic acid added to the soil during drought conditions had a higher chance of survival at 14 days. Another study showed that adding vinegar (acetic acid) to the soil of plants under drought conditions helped the plants survive longer when compared to water or other organic acids (8).
What is Cold Stratification? Cold stratification is putting seeds into a dormancy state with temperatures below 40° Fahrenheit for a specific period of time in order to improve the germination rate (the number of seeds that will sprout).