Vegetables are commonly divided into two groups – those that like cool weather and those that enjoy hot, summer temperatures. Salad greens, kales and cabbages are typical cool weather crops whereas tomatoes, basil and beans prefer warm soils and mild temperatures.
In mild areas, the first group can be sown directly into the vegetable garden in fall to germinate after a short winter. Cool weather vegetables can also be successfully winter sown in containers in the south as well as in colder northern areas. Furthermore you do not need expensive equipment and additional lighting to produce healthy seedlings. Some great cool weather seeds to try are Broccoli Raab or Dwarf Blue Curled Vates Kale.
Select a suitable container for your potting mix such as an empty gallon milk container or clam shell container from the supermarket. For milk jugs and other solid containers, cut three quarters of the way around the jug, about one third from the base, so that you have a hinge on the jug. Make a few drainage holes in the base and some vent holes in the lid of the containers before filling the lower half with potting mix. Moisten the mix and sow your seeds on top.
Seal the container with duct tape or other waterproof tape then place the container outside and leave it until the weather turns milder. You will see the seeds germinating when spring temperatures arrive.
Cool weather seeds can also be sown directly onto the ground where they are to grow. If you choose this method, sow the seeds thickly so that you account for animals eating some of the seeds, or seeds being dislodged by rain or snowmelt.
When warmer weather arrives you will need to check the seedlings regularly and lift the lid to avoid the container getting too warm inside. Extra water will also be needed as the weather settles. When the seedlings have at least two sets of true leaves, and the soil has lost the winter chill, transplant your cool weather seedlings into the ground.
Winter sown vegetables will germinate when the conditions are perfect, and the protection of the container will allow them to grow faster than direct sown seeds. Plus you get the bonus of having full light for all your seedlings rather than jostling seed trays around on a windowsill.