You’ve decided: This is your year. Your year to harvest armfuls of homegrown produce or flowers from your yard. To make salsa in summer, potato leek soup in fall and collard greens for New Year’s Day.
But there’s a lot to learn about vegetable and flower farming in Seattle’s unique climate, so we’re here with simple tips to set you up for a great growing season.
What do you eat?
The first decision is what to grow. To select how to spend your time, water and precious sunlit garden space, start with what you and your family love to eat. This will make you more attentive to your new plants and justify your time and effort.
Sometimes it’s a numbers game — it may be more efficient, for example, to buy a head of cauliflower than to weed and water a large plant all season long. Maybe that space would be better given to successive harvests of lettuce or peas, or to a super-productive cherry tomato plant.
“Most of us living in urban spaces are usually growing in a smaller area,” says Marni Sorin, community education manager for Seattle-based Tilth Alliance. “Start with what you like. What do you want to put in your salad or your dinner?”
How much do you need?
It’s easy to get carried away with visions of a bountiful garden and buy way too many seeds or plant starts. Starting small as you get to know your growing conditions — perhaps with one raised bed or a handful of pots — will save you money and heartbreak.
“Some beginner-friendly things to try are tender leafy greens like lettuce or arugula that are very forgiving,” Sorin says. “Also, peas are a great choice — you can put up a trellis support, or you can seed heavily and eat the pea shoots. They’re delicious. Even in a container you can build your self-confidence and success in gardening.”
Also, think about your motivation: Are you gardening as a hobby with some edible benefits, or with the aim of making a winter’s worth of tomato sauce?
“How much food are you hoping to get from your garden?” Sorin advises asking yourself. “Some are doing it as an activity with their children, and some are supplementing what they’re buying from the store.”
Where to grow?
Now that you’ve thought about which crops you want to eat, see if they will actually grow here, when they grow and how they grow. Okra, eggplant and sweet potato, for example, require more heat than our summers typically supply, but — with the right conditions — corn, tomatoes, pumpkin and even some melons are possibilities.
One of those conditions is ample light. Those heat lovers need at least six hours of direct, full sun, preferably with warmer south- or west-facing exposures, to fruit. If you have less sun than that — perhaps you only have an east-facing space or your south-facing bed is shaded by trees — consider crops that like cooler temperatures, such as lettuces, spinach, brassicas such as kale, and greens such as bok choy or arugula.
Another key condition is soil temperature; each crop has a preference. Plants can be stunted, drown or freeze in soils that are too cold for them. That’s why Seattleites typically transplant tomato starts in May when soil temperatures trend over 50 degrees. Washington State University keeps track of soil temperatures by date across the state, and Tilth Alliance’s planting calendar breaks down when to plant dozens of crops by month, including those with multiple sowings.
A bed against a sunny, heat-reflecting wall can help protect tender plants from cold nights and prime the soil for earlier growing. If you have a prepared bed, cover it with black plastic for around three weeks to preheat the soil a bit. Raised beds and pots are warmer and drier than level ground, but smaller pots will need frequent watering this summer.
What to plant now outdoors
Seed packets usually tell you when to sow; for example, four to six weeks before the last frost date in your area. That date is a moving target, based on climatic averages, but Seattle is usually frost-free by mid-April.
Peas, lettuce, spinach, brassicas and greens can be sown in March and April in an area protected from the coldest winds. Cover the seeds and seedlings with row fabric if the forecast calls for a dip in temperatures.
Sorin also recommends sowing carrots, beets, cilantro and fennel, as well as seed potatoes in March and April. You want to wait to sow your seeds until the ground is easily crumbled and loose, not muddy, she says.
Also, she adds, watch the weather: “You don’t want to plant the seed potatoes in the ground and then it rains for two weeks. You want to pick a dry time.”
Follow the spacing requirements for each plant to allow for growth and air flow. Overseeding works for microgreens or cut-and-come-again lettuces that you harvest early. But plants grown to full-term suffer from the competition.
Space-saving measures include adding vertical trellises for vining crops like peas, beans and cucumbers, and using “square-foot” gardening in which plants are arranged in 1-foot squares to maximum density. Find those spacing requirements in WSU’s “Home Vegetable Gardening in Washington” e-booklet.
As for flowers, many cutting-garden favorites love cooler temperatures. Fragrant sweet peas, annual poppies, edible calendula and otherworldly nigella will thrive if sown in the soil now. Sorin also suggests alyssum, forget-me-nots and bachelor’s buttons. Wait until late April to sow sunflowers outside.
What to plant now inside
Even Seattle’s sunniest south-facing windowsill may not provide enough light to get some seeds to germinate. Most plants will grow best indoors under supplemental grow lights. There are now many options for these lights, including fluorescent and LED varieties, compact lamps, under-shelf strips and shop lights.
Seeds can be sown in kits that include seed-starting mix and plastic covers, or you can make DIY planters from newspaper or egg cartons. If you’re growing without lights, time your plants so that they can move outside as fast as possible.
Let’s take, for example, the nation’s most popular veggie to grow: the tomato. Since tomato seedlings shouldn’t be planted outside until mid-May, and they need six to eight weeks to grow from seed to seedling, you want to count back six to eight weeks from about May 15. That means you should plant your tomato seeds inside between March 20 and April 3. They will need a heat mat until they germinate and, preferably, a grow light.
Or just go to the nursery in May and avoid all that coddling. “Seed-starting is really fun and rewarding and can give you a better relationship with your garden,” Sorin says. “But there’s no shame in buying starts.”
She notes, though, that some crops will do better if you grow them from a seed versus a start, including beans, peas and root crops such as potatoes, beets and carrots.
On the other hand, while cold-loving peas and leeks can be sown outside, Colin McCrate, co-founder of Seattle Urban Farm Company, prefers to start them inside to stymie slugs. Slugs love to snack on tender new leaves, but those leaves are gone when transplants are set out in April. He says he sees “a higher rate of success” this way.
For instant gratification, McCrate says, you can’t beat lettuce grown from seed. “Romaine or butterhead lettuce are the fastest, most reliable things to do as a transplant — very satisfying” he says. “Those can be started in March and put out in April, because within two weeks of seeding they are ready to go out.”
Summer flower garden stars to start indoors now include cosmos, marigolds, scabiosa, stock and phlox.