Seed Starting Calendar Guide
Olympia has a pretty mild climate, with wet winters and cool, dry summers. Our USDA hardiness zone is generally 8b, meaning we can grow a variety of plants, but our growing season tends to be a bit shorter compared to warmer regions. Frosts can still occur in early spring and late fall, so timing is key when starting seeds indoors or directly outdoors. To read all about what you can do in your garden when March comes, read this blog.
In general, Olympia's growing season begins in early spring, but the specific timing can vary depending on whether you're growing flowers, vegetables, or herbs. Our average last frost date falls around April 15th (but keep an eye on the weather forecast to be safe!), while the first frost date is typically in mid-October. Keep this in mind as you plan out your planting schedule!
Starting Seeds Indoors: Best Times for Flowers and Vegetables
Many gardeners like to start seeds indoors to get a jump on the growing season (or maybe we just can’t wait!) Starting seeds indoors can give plants a strong, healthy start, especially for those with a longer growing cycle or a need for a longer frost-free period.
But Be Careful: Starting plants TOO early, without a place to transplant, can become chaotic… their roots need room, so you either need to “pot up” to a larger container, or plant them out. Decide what’s right for you!
Getting Started Growing Indoors
You’ll need:
an area of your house that won’t be disturbed by children, animals, spouses, etc. Maybe the closet? Maybe the guest room? Maybe under your bed?? (LOL please send pics if you do end up growing plants under your bed, because that mental image is hilarious…)
grow lights, and there are SO many options. You can find some that clip-on like this, or hang like this, or free-standing like this… you get the idea!
starter soil with no big chunks (you can sift through a screen if needed)
Starter Trays, or soil blocker - I LOVE MY SOIL BLOCKER. It takes some practice getting the soil just right (another blog/video on that coming soon!) but once you get the hang of it, you never have to use starter pots again! If you are using starter pots, I highly recommend asking neighbors for old starter trays or pots! Everyone seems to have old ones lying around.
Vegetables
For vegetables, starting seeds indoors allows them to grow strong before being transplanted outside. Here are some key vegetables and the best times to start them indoors:
Tomatoes: Start indoors 6–8 weeks before the last frost date (late February to early March).
Peppers: Start indoors 8–10 weeks before the last frost date (early February to early March).
Broccoli, Cabbage, and Cauliflower: Start indoors 6–8 weeks before the last frost date (mid-February to early March).
Lettuce, Kale, and Spinach: Start indoors 4–6 weeks before the last frost date (early to mid-March).
Squash (Summer and Winter): I typically will presprout the seeds and direct sow them at the very end of May
Once your indoor seedlings have grown large enough and the outdoor temperatures are consistently above 50°F (about 2–3 weeks after the last frost), you can begin hardening* them off and transplanting them into your garden.
(*more info below about hardening off plants)
Flowers
Many flowers can be started indoors, especially those with longer growing seasons or that require a longer warm period. Here are some of the flowers I like to start indoors EARLY (like, January!) to give them enough time to grow:
Lavender (and other perennials!)
Lisianthus (I don’t grow from seed, but they require a very long time! Start ASAP!
Eucalyptus
Summer Flowers like zinnias and sunflowers can be direct-seeded once the last frost has passed, but many others benefit from a head start indoors.
Direct Seeding Outdoors
While starting seeds indoors is common, some crops and flowers do better when directly sown into the garden, particularly those that don't mind the cooler temperatures or those with shorter growing seasons. In Olympia, this is a good option for vegetables and flowers that can tolerate early planting or cool conditions.
Vegetables:
Peas: Direct seed outdoors as early as late February, as they thrive in cooler temperatures.
Radishes: Direct seed outdoors in mid March.
Carrots, Beets, and Turnips: Direct seed outdoors in mid March.
Spinach and Arugula: Direct seed outdoors in early April.
These crops can withstand a bit of frost, and they often perform best when planted directly outdoors, especially when the soil is still cool and moist.
Flowers:
Sweet Peas: Direct seed outdoors any time from October - March, or start indoors in February/March (I like to start indoors, you can read about my Sweet Pea tips here
Poppies, Bachelor Buttons, Nigella, Calendula, Larkspur: Direct seed outdoors any time from October - February.
These hardy annuals love the cool weather and will do well when direct-seeded into your garden in early spring.
Hardening Off and Planting Outdoors
Once your seedlings are ready for the outdoors (typically after 6–8 weeks indoors), they need to be acclimated to the harsher outdoor conditions. This process, known as “hardening off,” involves gradually exposing your plants to outdoor temperatures, sunlight, and wind over a period of about 7–10 days. This helps reduce transplant shock and ensures your plants adjust smoothly to their new environment.
Start by placing your seedlings in a sheltered spot outdoors for a few hours each day, gradually increasing the time they spend outside. After a week or so, they’ll be ready to be planted in your garden beds.
I also found this helpful guide with several plant varieties and their planting time!
I tend to “push the limits” when it comes to the suggestions on the seed packets. If a crop is considered “cold tolerant,” they can be planted out pretty much any time! Just avoid severe frosts (or protect as well as possible) and you should be fine!
Let me know how it goes!
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