Gardeners, start your engines. While there is gardening joy to be had every day of the year in some form, you can’t put a price on the day the soil temperatures hit 60 degrees, signaling the gardening season is OPEN in Seattle.
What does this mean? The caution tape is off the garden beds. For all the plants that like it a little warmer, you have permission to set out or sow them now. You can plant your tomatoes and squash, basil, zinnias, sunflowers, and dahlias.
Tender Plants Strategies
I will offer one caveat: if plants are being sold under cover in a greenhouse, even open-air, they may benefit from being exposed to the outside world gradually.
This is called “hardening off”, and it applies whenever a plant needs to go from inside to out – for seedlings started under grow lights, houseplants coming out for the summer to get infusion of sunlight, and for nursery plants that haven’t been outside yet. The only way to know is to ask the staff if they’ve been hardened off. If they are outside, they may have just arrived from a truck or greenhouse. If I bought a plant in a greenhouse, and it’s going to be cold at night, that baby is coming indoors to my unheated but sunny porch until I can plant it.
As a result, I had two sets of tomatoes that came from different conditions I hardened off separately. One garden clerk told me “I never bother with that. They may stall for a few weeks, but I just let them figure it out.” While I applaud the devil-may-care attitude, for tomatoes specifically, it’s not worth the risk to stall them in Seattle’s short season. Side note: tomatoes also grow best when air temperatures are reliably over 50 degrees, which I hope has happened by the time you read this. You can add a few degrees by planting up against a sunny wall, red plastic mulch, surrounding with “Wall of Water” protectors, milk jugs filled with water, or large stones/bricks warmed by the sun.
Some plants are fine out it in a slight chill, like sweet peas, nasturtium, calendula, poppies, garden peas, and lettuce. I winter-sowed my sweet peas and they have been in the ground for about a month already.
Once you check soil temperatures, either with your own soil thermometer or looking on weather sites, you can sow or plant a cutting garden, fresh herbs, dahlia tubers – and of course potted perennials, trees and shrubs hardy to your USDA zone – in Seattle’s case, zone 9a now.
What I’m planting
I just planted several winter-sowed native pollinator plant seedlings, from California poppy (Eschscholzia californica) to several species of baby blue-eyes (Nemophila). Well, there are about 20-odd tomatoes waiting for their moment to be planted. In addition, I’ve got a host of Floret Farm specialty zinnias and cosmos seeds to sow and about 10 dahlias to plant (thank you, Puget Sound Dahlia Association sale). I purchased a fun new ‘Lettuce’ basil with wide wavy leaves that will be a fun accent in the veggie bed. Like tomatoes, basil really wants to wait until the air is nice and toasty to thrive. Another basil I love is ‘African’ which has dark purple leaves, a taste more Thai anise than Italian, and flowers that don’t need deadheading. It’s pretty cold-hardy, too.
I am also replacing parsley, arugula, and pineapple sage.
Pineapple sage and lemon verbena are two specialty herbs I adore. The first has fuzzy leaves, sometimes leaning golden, that taste like pineapple – a friend told me he likes to put it on fruit salad, especially with strawberries.
At summer’s end, it sends up dramatic red salvia flowers that look wonderful. Lemon verbena would be worth having just for the aromatherapy. In a low moment, one rub of those leaves transports you to a new citrusy reality. Both of these used to benefit from some protection in winter here, and always perfect drainage, but perhaps in our new zone 9a lifestyle, who knows?
That’s not counting the specialty annuals and perennials that followed me home while shopping for tomatoes, parsley and pineapple sage. Like a kangaroo paw (Anigozanthos) which is hardy to zone 9. Even though Seattle may be Zone 9, the weather doesn’t always follow the rules, but I’m not ready to break up with zone-surfing yet.