Seed Stratification - What Is It and How To Do It At Home
Growing plants from seeds is a great way to get lots of new plants for relatively cheap. Even brown thumbs know the basic principle of tossing a seed in the ground and watering it. But some seeds just need a little extra kick to help them along and knowing about this process can help you save time and money on wasted seeds. In their natural environment, plants will undergo specific conditions as part of their normal lives.
When these conditions are extreme, their seeds can evolve to the point where they wait for these extreme conditions to pass and be ready to germinate when the good times come rolling through. This could be a freezing cold winter, a sweltering hot summer, or a regular forest fire season. This exposure process is called stratification and means the exposure of a seed to a specific condition that breaks the seed’s dormancy and allows germination to occur. Some seeds need a warm, moist stratification process, and some need a cold dry one. Sometimes seeds need a mix of both warm and cold treatments or even wet and then dry. It’s important then that you research what process your specific seeds need before you start trying to germinate them.
Stratify Me.
There are two main types of stratification that seeds can require before they’ll germinate – Dry and Moist. Dry stratification is a process where seeds are exposed to cold, dry temperatures of <0˚C for at least a month and are intended to imitate a cold winter.
You can do this at home by placing your seeds in an airtight container and placing them in a fridge or freezer.
Moist stratification exposures seed to cold and damp conditions to simulate a cold wet winter. As the seeds are removed from these conditions the warming Spring weather is simulated, and seeds are ready to germinate.
You can do this by placing your seeds in an airtight container with some moist sand, sawdust, peat moss or coco-coir and keep in the fridge for a month. Don’t use the freezer for moist stratification though, as the water will freeze, and this can damage your seeds.
All This Aggravation Ain't Stratificationing Me.
While most seeds just need a wet or dry stratification, there are exceptions. Lots of seeds need various combinations, or different types of stratification before they can germinate.
Some seeds will need to undergo a double dormancy period before they’ll germinate. This is because the seed needs to undergo a process to break down the outer seed coating first, and then be exposed to a cold period to remove the internal dormancy of a cold winter.
In these cases, seeds will need to undergo a cold period for a month or so, then undergo an extended warm period, followed by another cold period. You can help double dormancy seeds along by roughing up the outer layer of the seed via scarification after the first cold period.
Some seeds may even need one of their cold periods to be moist and the other dry. Each seed can be different, so researching plants with double dormancy is a great idea before you buy any seeds.
Hot stuff Comin’ through!
Some plant species have evolved to germinate in winter, or only after wildfires have passed through. To ensure this, their seeds require exposure to high temperatures to break down their outer coating before they can germinate. You can use warm water and scarification on seeds to mimic hot summers or wildfires, and then germinate your seeds normally.
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