To achieve germination with seeds having double dormancy, the seeds must first be scarified and then stratified for the appropriate length of time. If the treatments are administered in reverse order, the seeds will not germinate.
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.
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.
Seed stratification is the process of exposing the seed to moisture and cold so that the hard seed covering will soften and allow the seed to successfully germinate. Seed scarification is the process of mechanically altering the outer seed coat to allow for water uptake and improve seed germination.
Stratification is a general term that refers to a range of processes used to simulate natural conditions (typically temperature and moisture) that seeds require before germination can occur. Scarification refers to various techniques used to break physical dormancy (explained below).
Refrigeration. Depending on the seed species, you may need to refrigerate seeds for as short a time as 10-days, or as long as one to three months. 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.
Examples of annual seeds needing scarification include sweet pea and nasturtium. Many cold hardy perennials like delphinium and columbine also have tough coats. This group often needs both scarification, to soften the seed coat, and stratification (a chill period) over time to trigger germination.
Place peat moss/seed mixture in a ziploc bag and seal. Label the variety and date clearly on the bag. Place in the refrigerator for 1 month before planting. If seedlings start to sprout in the bag in the refrigerator, remove immediately and either plant in the ground or in pots until it's time to plant outdoors.
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!
Seed should be planted ½–1.0 in. deep, and should be scarified to break the chemical and physical barriers to germination. Seed scarification is the process of altering the seed coat to allow quicker water absorption and improve rates of germination.
Scarification is a pretreatment of seeds that aims to break seed dormancy and accelerate the occurrence of uniform seed germination. Scarification is a way to provide a permeable condition of seeds through puncturing, burning, breaking, filing, and scratching with knives, needles, sandpaper, and other tools [1].
When considering both aerating and scarifying, it's better to scarify first, then aerate- but leave a few days in between the two exercises to allow your lawn to recover before you put it through all that work again.
Spring: Raking & Light Scarifying
Spring generally means sometime in April just as things warm up thereby increasing the growth and recovery rate but before the heat and dryness of summer slows things down. Autumn would generally be late August or September as the rains start but before the cold sets in.
That being said, there are certain times of the year that are more suitable than others. Late spring and early autumn are considered to be the two best times to scarify your lawn, capitalising on both the weather and the conditions of the ground.
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.
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. Because this is a potential issue, it's best to check on stratifying seeds every couple weeks.
*Cold stratification means to place the seeds in contact with moist cool soil, simulating winter. Refrigeration usually works well, but you must make sure the seeds are moist!
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.
This method of planting has been done by humans for generations and works very well. Cold dry stratification can be accomplished by placing seed in a sealed container in a refrigerator for a period of time.
You want to scarify the opposite end, so you don't damage the eye. Run the end of the seed back and forth along the file a few times, just enough to rub through the outer coat. Follow up by soaking them for a few hours, if you like.
We recommend using 100-150 grit sandpaper. For the clipper method, make sure the seed is big enough for you to hold and cut safely. You only need to nick the shell enough to see a little bit of the inside. Very little shell needs to be removed for scarification to work.
The most common type of scarification is mechanical scarification. In mechanical scarification, the testa is physically opened to allow moisture and air in. Seed coats may be filed with a metal file, rubbed with sandpaper, nicked with a knife, cracked gently with a hammer, or weakened or opened in any other way.