If you’ve opened a half a dozen vegetable seed packages, you’ll realize how much their sizes can vary. These different sizes are going to affect how you plant them.
Big runner bean seeds are easy to sow individually at the proper spacing for them to grow. Tiny carrot seeds, however, are not so easy and have to be sown in a line – and then be thinned out as they grow to allow for the proper spacing.
The size of the seeds also affects how deep you should sow them. Seeds contain “food” reserves that keep them nourished from the point of germination until they break through the soil into the light. Larger seeds contain more food and can last longer than small seeds.
If you plant smaller seeds too deep, they can run out of food before they have a chance to break through the soil and reach sunlight.