Seeds Series: Crops to Seed Directly in the Soil

  • Difficulty Rating: Beginner


Cucumber seeds ready to sow

Soil temperatures should be warming, the danger of frosty nights should be past, and sunlight should be more abundant, which means it’s time to begin sowing crops directly into the earth.

By now, most of the seeds you started indoors in winter have grown into young plants that are now hardening off or are growing steadily in their final garden bed destination.

Soil temperature can make or break your seed’s chance of germination success. And, the temperature at which each seed will break forth and grow varies. Cool season crops may grow just fine when soils are as low as 50 degrees, but warm season growers need the temperatures to be well above 60 to have any chance at success.  If you did not pick up a soil thermometer when you started seeding indoors, then now is the time to get one. Once you have it, pop it into your garden bed and let it rest for 30 minutes or more to gauge your soil’s true warmth. (Or just read what the manufacturer recommends for your chosen brand as functionality may vary.)

Rich garden soil in Big Grip Trowel


Got cold soil? Go ahead and direct seed cool lovers like beets, carrots, spinach, cilantro, lettuce, chard, and mesculin mixes. Although some of these may be crops you grew indoors from seed earlier, they are also ideal for direct seeding and rapid harvesting via thinning, which I’ll cover in next month’s article. Plus, even if soil temperatures continue to warm, these seeds will turn into tasty plants quickly.


Two-tone Scarlet Runner Bean Flowers


If your soil temperature registers in the 60+ range, you should be in good shape to seed crops like Scarlet Runner Beans, cucumber, peppers and melons. But, be sure to double-check the seed packet recommended temperatures just to be sure. Some, like eggplant and watermelon, may need the soil to be in the 70-degree range for any chance of success.

If you garden in a cool season environment like I do, employing season extenders to help warm the soil and the crops themselves can make all the difference. If your soil just cannot get warm enough for optimal direct seeding, building a greenhouse environment over the ground can help warm up the soil fast. Creating a hoop house, building a cold frame, adding a cloche, or even just floating a bit of horticultural fleece over the ground can bump temperatures over the too-chilly mark.

Keep in mind that plants in the squash group like cucumbers, melons, pumpkins, and zucchini do best when planted where they will grow for the duration of their short lives. Their rooting system does not do well when disrupted during transplanting, and it prefers warm, loose, easy-to-travel soil, so creating raised mounds into which you sow your seeds is a great approach. Plus, by mounding up a little flat-topped mountain for them, you create a space that should offer lots of warm, surface soil for their delicate, heat-loving roots to explore.


Last time in this series: Taking Your Transplants to their Final Destination

Next time in this series: Thinning Your Direct-Seeded Crops