Recently, I posted an article called Tips for Starting Seeds for Your Garden. The post was about starting seeds and the importance of distinguishing between warm versus cool season plants or seed. It further explained how and when to sow seeds for warm season plants. This is the second part of the post: a focus on cool season plants.
Starting Seeds in Ground or Containers
In my zone 7 Northern Virginia garden, there are many vegetable and herbs that I can start growing outside in early spring. This means I don’t have to start them indoors under lights. Not only do these particular plants prefer cool temperatures, a light frost should not harm them. I tend to start most of my cool season plants by seed in containers on my deck. Container soil is warmer than ground soil. Also, it is easier to check on them by walking on a wooden deck than to have to trample through wet, soggy soil in cold weather. By summer, most of these types of plants have bolted (i.e., flowered and gone to seed so leaves are bitter). After pulling and discarding into the compost pile, I re-stock my containers with warm season annuals such as different types of basils and bush beans.
When to Sow Seeds in Early Spring
Using davesgarden.com and my zip code, I calculated my average last frost date to be April 30. March and April are still cool and there is a possibility of a frost or even snow. From the list of cool season plants or seeds I want to grow, I calculate which I can start at what number of weeks before April 30 and which would benefit from containers on the deck or directly into the soil. If a seed packet does not provide this information, try asking your local extension agent, online seed catalogs, or read a printed seed catalog or a gardening book. A few online seed catalogs that provide quality descriptions for this are Burpee, Johnny’s Selected Seeds, Botanical Interest, Southern Exposure Seed Exchange, and Renee’s Garden.
Sowing Often for Continuous Harvest
For some cool season crops, sowing every couple of weeks ensures a continuous harvest until summer. For example, our family likes to eat lettuce and spinach so if I start sowing in early spring and again every other week, I will be able to continue to pick leaves for a family of four up until summer. By summer, the weather will be too hot to germinate spinach and lettuce easily.
Check if the seed package recommends growing in soil or if they can be grown in a container. If you only need a little arugula, grow in a shallow container. If you only need one borage plant, grow in a larger container (it is a larger plant). Chervil is so ephemeral it is best to grow in a medium container so you can access and harvest as much as possible. For plants that tend to flower and drop seed, I find it helpful to have a patch set aside. I have parsley, cilantro, and calendula patches in the backyard so I sow the seeds directly in those patches. Of the plants below, peas are the only ones that need vertical structure. They should be planted next to a trellis and “trained” to wrap around it. I grow sugar snap peas in the ground next to a wire trellis but there are some variety of peas that can be grown in containers with stakes. Here are common cool season plants that can be grown by seed:
- Asian greens
- Chinese cabbage
- Pak choi
- Sweet peas
My Cool Season Seed Plan
Just before March 15
Burpee and Botanical Interests Sugar Snap Peas: Soak overnight in water and then plant seed in small plastic pots with soil. When 2 inches tall, transplant outside in ground against trellis. No need for indoor lights.
- Southern Exposure Seed Exchange calendula ‘Resina,’ sow directly in calendula patch in ground
- Lake Valley Seed Chervil, sow directly in medium size container on deck
- Charles Hart Seed Company Chinese Cabbage, sow directly into soil
- Renee’s Garden Heirloom Russian Kale ‘Wild Garden Frills’, sow directly into ground and in medium size container, can repeat again in few weeks.
- Lake Valley Seed ‘Cherry Belle’ Radish, sow in small containers, can repeat in a few weeks in other containers
- Renee’s Garden Italian Large Leaf parsley, sow directly into parsley patch in ground
- Lake Valley Seed Japanese Mustard ‘Mizuna’, sow directly in ground and a medium sized container
- Lettuce: all start in medium containers and in ground (more success in containers because of birds and animals), repeat every two weeks in different containers, areas in ground
- Spinach: all start in medium containers and in ground (more success in containers because of birds and animals), repeat every two weeks in different containers, areas in ground
- American Meadows Scarlet Nantes carrot, sow in large deep container on deck and in ground
- Renee’s Garden Slo-Bolt Cilantro, sow directly into cilantro patch in ground
- Repeat lettuce, seed, radishes, and kale
- Start borage in large decorative container
- Start arugula in medium container