Seed Stratification vs. Scarification: Techniques for Successful Planting

There is not much more frustrating than planting seeds and not having any germinate (sprout). There are several reasons this may happen.

• The seeds may have needed stratification

• The seeds may have benefited from scarification

• The seeds may be too old

• The seeds may have been stored incorrectly (Find out how to properly store seeds here)

  
  

My hope is that by helping you better understand seed stratification and scarification needs you will no longer deal with seeds not germinating!

What is Seed Stratification?

Seed stratification refers to exposing seeds to a period of cold temperatures - most often just below freezing. This cold period mimics winter in nature and when seeds are warmed after being stratified this indicates to the seeds that it is spring and that it is safe to sprout.

This stratification is the reason some seeds fall to the ground during summer months but do not sprout until the next spring.

The time needed for stratification generally varies from two weeks to one month.

Seed Stratification List

Generally, you can expect that any perennial that grows naturally in a cold climate with benefit from cold stratification. There are also a number of annuals that benefit from cold stratification. Here is a list of seeds to cold stratify.

Flower & Herb Seeds to Cold Stratify:

• Chamomile

• Columbine

• Delphinium (Larkspur)

• Echinacea

• Globeflower

• Hollyhock

• Lavender

• Lobelia

• Lupine

• Rudbeckia

• Scabiosa

• Sunflower

• Sweet Pea

• Viola

Vegetable Seeds to Cold Stratify

• Artichoke

• Asparagus

Although most vegetable seeds don't say that stratification is required, I do recommend at least a 3-week period of fridge temperatures for any seeds that you kept over the winter.

Note that most berry seeds require cold stratification.

If you are purchasing seeds from a reputable company they should have been stratified before being shipped. When storing seeds purchased from the previous year you won't want to miss performing this step yourself!

You can't see the seeds, but I AM planting some.

How to Cold Stratify Seeds

I find it easiest to cold-stratify ALL of my seeds. This way I don't miss any. Also, although all seeds don't require stratification it can help improve germination rates.

Cold stratify your seed box/bin by placing it in a dark, dry location in a shed or maybe an unused holiday trailer over the winter. Dry is key here.

Tip: Throw some silica packets in with your seeds to absorb any moisture.

This is where I store my seeds (when there is room in the beer fridge).

Every time seeds warm up from fridge temperature to room temperature there is some moisture build-up. Avoid taking your seeds in and out of the fridge any more often than you need to.

Winter sowing seeds is a great way to allow for natural stratification. You can find out more about winter sowing here.

What is Seed Scarification?

Seed scarification is the process a seed goes through that causes nicks and scratches on the hard outer shell of the seed. In nature this can happen as the wind blows the seed across land or when animals ingest seeds and they travel through the gastrointestinal system of the animal.

How to Scarify Seeds

Seed scarification can be done by:

• Lightly rubbing seeds between a folded piece of sandpaper

• Running a file over seeds

• Filling a bag or jar with dry, rough sand and shaking vigorously.

Sandpaper ban be used to scarify seeds.

What Seeds Require Scarification

Many hard-shelled seeds benefit from scarification. Read your seed package carefully to see if comments suggest scarifying seeds. Sometimes this may be done for you by the company you purchased your seeds from.

Seeds that benefit from scarification include:

• Asparagus

• Columbine

• Morning Glory

• Nasturtium

• Strawberry

• Sweet Peas

Beautiful nasturtium seeds collected form my garden.

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