If you’re itching to get your hands in the soil and get a jump start on your spring/summer garden but know that it is too early to do so outside, then now is your prime opportunity to start your favorite spring/summer annual flowers and vegetable seeds indoors. The first warm days of March often tease us into thinking it is time to plant our tomatoes and basil. While you may have spring fever, the outdoor soil temperatures are not warm enough yet to start your spring/summer annuals and vegetables. So why wait? Let’s get you set up to start seeds indoors to extend the growing season while frost is still possible.
It is best to start your spring/summer annual and vegetable seeds indoors about 4 to 8 weeks before the last spring frost depending on the plants you are starting from seed. In Napa Valley, the last spring frost generally happens around mid-late April.
Recipe for successful seed starting:
Viable seed – unexpired seed that has been stored in a cool, dry place. Follow seed package directions for seed planting depth and spacing. We sell Renee’s Garden and Cornucopia seeds; both are GMO free!
Growing medium – a soilless mix like EB Stone Organics Seed Starter Mix.
Growing Containers – shallow seed starting trays with individual cells for planting and drainage holes. Plastic, fiber or CowPots work well. Use individual 3”- 4” pots for crops that do not like to have their roots disturbed like corn, cucumbers, melons and squash.
Heat source for soil – seed starting mats are your best bet to warm your soil up to the appropriate temperature for germination. Ideal soil temperature does vary for different plants. Once seeds have germinated and plants are established, seed mats may not be necessary.
About 2-3 weeks after you have started your seeds and they’ve reached the first true leaf stage (second set of “leaves”) you will need to provide:
Supplemental lighting – Choose a full-spectrum plant grow light hung 3-6” from the tops of the plants. Vegetables need about 14 hours of light per day. This will help to keep the plants from stretching in their attempt to reach for light.
Nutrients – We recommend using G&B Organics All Purpose Liquid Fertilizer. Do not use fertilizer prior to the emergence of the first true set of leaves as it may negatively impact water uptake and root growth.
Potting up – Once your seedlings have formed 4 sets of true leaves, move them from the small seed starting trays into larger 3”- 4” containers filled with potting soil such as EB Stone Organics Edna’s Best Potting Soil. Be very careful not to damage the roots when transplanting into a larger container. Remember from the left that some plants are better started in larger containers and only transplanted once it is time to plant them in the garden to minimize root disturbance.
Hardening-off and planting outdoors – The date you set your plants out or transplant them in your garden depends on the plant. Some plants such as peppers and pumpkins require warmer outdoor and soil temperatures. Consult a gardening resource, such as us, if you have any questions here. In general, for spring/summer crops you can transplant 1-2 weeks after the last spring frost. Before you transplant your seedings into your garden, you will need to gradually acclimate them to outdoor conditions. The best way to do this is by placing your plants in a shaded, covered area for a few hours during the day and them bring them indoors at night. Gradually increase the amount of sunlight and time they spend outside. This will take about a week to do and then they will be ready to transplant into your garden.
Spring/summer annuals and perennials to start by seed indoors: Bachelor’s Button, coleus, columbine, Delphinium, Echinacea, Gaillardia, larkspur, marigold, milkweed, Sweet William, sunflowers, zinnias, etc. Continue to plant cool-season flowering plants in the garden from starts. Pansies, violas, primrose, ranunculus, poppies, etc.
Spring/summer vegetables/herbs to start by seed indoors: Basil, cucumber, eggplant, melons, peppers, pumpkins, squash, tomatoes, etc. You can start beans and corn indoors, but they are best direct sowed into the garden in late April or early May.
Continue to plant cool-season crops directly in the garden from starts. Beets, carrots, collards, mache, kale, leeks, lettuce, onions, peas, swiss chard, etc.
By ALI WHITE
Garden Center Manager