In the gardening world, germination refers to the process by which seeds are brought out of their dormant state to begin development.  Water, oxygen, soil temperature, and sometimes light are required for the process. 

When planting seeds, you can do everything right, and yet some seeds simply will not germinate. Even in nature, not all seeds produced by a plant are guaranteed to grow. Thankfully, there is a way to know what your chances are that a particular variety of seeds will germinate if given the proper conditions.  It’s called the seed germination rate. A germination rate of 75%, for example, means that 75 out of 100 seeds will likely germinate if sown in a favorable environment.  

Seed Germination Rates

Some plant varieties have a higher germination rate than others.  So how do you know if the germination rate for a batch of seeds is low or if it is normal for that variety?  In 1940, the United States Congress enacted the Federal Seed Act, which requires seeds sold in interstate commerce to have a minimum germination rate per plant variety. The law created an industry standard to protect consumers from purchasing unviable seeds. For example, by law, cauliflower seeds must have a minimum germination rate of 75%, while Swiss chard seeds are required to have a minimum rate of 65%.  Cucumbers must have a minimum 80% rate compared to a 50% rate for okra and chives. Seed companies will often provide additional seeds in each packet in order to comply with these standards.  You can find out the minimum germination rate for almost 50 varieties of seeds by consulting the chart below.  This information can be helpful in choosing a seed company to purchase from.  For instance, if you plant seeds from a company, but the germination rate falls below the minimum standard, even though you planted them in favorable conditions, you may need to consider purchasing from a different company.

How to Test for Viability  

Seeds deteriorate over time.  Thus, the age of the seeds can affect the germination rate as well.  If you are going to use seeds that are over one year old, it can be helpful to test their viability so that you will know how many seeds to sow in order to get the number of plants needed to produce the desired harvest.  Here’s how to conduct a simple viability test.

What you will need:

• paper towels or coffee filters
• plastic bag with zip closure
• water and a spray bottle
• seeds you want to test
• pen to label the bag

Directions:

1. Moisten a paper towel or large coffee filter so that it is saturated but not dripping wet. 
2. Select a random sampling of at least ten seeds from the packet you want to test.
3. Place the seeds on one half of the damp paper towel and fold the other half on top of the seeds.
4. Place the damp paper towel with the seeds inside a plastic bag, folding it again if necessary so it will fit. Label the plastic bag with the date and seed type if testing more than one kind of seed.  Close the bag and place it in a warm, dark place. 
5. Every few days, check the paper towel to see if any seeds have germinated. Count only the ones that have healthy looking root and shoots.  Also, remoisten the paper towel as needed with a spray bottle to keep it evenly moist.
6. After about 10 to 14 days (more or less depending on what kind of seeds they are) note how many seeds have germinated. Divide the number of seeds that germinated by the total number of seeds you tested.  Then multiply the sum by 100 to get the germination rate.  For example, if you started with 20 seeds and 15 seeds germinated, the equation would be 15 ÷ 20 = .75; .75 x 100 = 75.  Thus, the rate would be 75%. 
7. If it took longer than expected for the seeds to germinate and the germination rate was less than 50%, it is a good idea to purchase new seeds.

You will need to factor in additional time to your seed-starting schedule in order to allow for the test.  For example, if you want to plant seeds on February 15, you will need to start testing seeds on February 1st (or earlier) in order for the test to be completed by seed sowing time.

Some seeds, especially those with a hard, thick, or rough seed coat, may require scarifying, which is the process of softening or scratching or abrading seeds to increase their permeability.  You can learn more about this easy process to increase and possibly speed up germinations rates in this helpful article.

With just a little bit of planning, you can sow seeds this season with confidence because you will know they are viable and likely to produce a harvest. 

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