Ideal soil temperatures for seed starting

Saturday, April 14, 2018

Adding some bottom heat can greatly increase the germination rate of many vegetables, particularly the heat loving veggies, in the spring.  In the summer, you may need to start seeds indoors or in a shady area.

Summer veggies like tomatoes, eggplant, peppers, cucumbers, squash, and beans love a little extra heat.  Tomatoes, eggplant and peppers need temps at least 60 F to germinate in a timely manner.  If you try and start the summer lovers in cold soil, many times the seed will rot before it sprouts.

A good rule of thumb is at least 70 F soil temps for starting summer veggies indoors.  You can buy a simple, cheap heat mat at any big box store.  For a list of germination rates by temperature and crop, this is a good link http://tomclothier.hort.net/page11.html

For cold crops, hotter is not better.  Lettuce will not germinate if the soil is above 80 F.  This is the reason you may need to start lettuce indoors during the dog days of summer unless you have a cool, shady spot to start the seeds.

Seeds sprouting in an Aerogarden

If you want to go high tech, I found that using an Aerogarden with the seed starting insert gave an almost 100% germination rate.  Here is a link to their web page:  http://www.aerogarden.com
Look for the "Garden Starter System" accessory for the seed starting insert.

It can be tempting to start all your seeds as soon as you get them.  If you are starting them outdoors, be sure they are sown when the temps are right for the type of crop.  If growing indoors, you can modify the conditions to what suits the type of veggie you are sprouting.

For more on seed starting tips, see Indoor seed starting tips