The Fall Equinox in My Seattle Kitchen Garden

What the equinox is, why I celebrate it, and the garden jobs that belong to this week.

Evening sun through the big tree over my beds. From here we lose a few minutes of light every day until March.

The fall equinox in Seattle arrives this Tuesday, September 22, at 5:05 in the afternoon. For a moment day and night are almost exactly the same length, and then the nights start winning. They keep winning until March.

For me this is a day I celebrate. It is a kind of pagan holiday in my house, a harvest festival and a moment to stop and look at what the garden gave us this year before everything slows down. I spend the day in the garden, start decorating the house for fall, and think back on how the summer went. Mostly I just breathe and enjoy a quiet, calm moment before the fall work starts. You don't need to celebrate anything to use the fall equinox in Seattle as a garden date, though. It is one of the most practical dates of the year, and here is why.

What the fall equinox actually is

The earth is tilted, and that tilt gives us seasons. Twice a year the sun sits directly over the equator, and everyone on the planet gets roughly twelve hours of day and twelve hours of night. The word comes from Latin and means equal night. In March that moment starts spring. In September it starts astronomical fall.

The date moves a little from year to year, usually the 22nd or the 23rd. This year the exact moment is 5:05 p.m. Pacific time on Tuesday, which is already early Wednesday morning in London, so you will see both dates online. Weather forecasters use a different fall that always starts September 1, because whole calendar months are easier to compare. Both are correct. The garden follows the sun.

People have marked this day for a very long time, because for most of human history it was the working end of the harvest. Many modern pagans call it Mabon. In Germany, where I grew up, the harvest festival is Erntedankfest, a couple of weeks later on the first Sunday in October. Different names, same idea: bring the food in, say thank you, and get ready for winter.

Why the fall equinox in Seattle matters for your garden

Plants grow on light. From the equinox on we lose a few minutes of daylight every day, and at our latitude that adds up fast. By early November our days are shorter than ten hours, and most vegetables almost stop growing until February.

Here's the thing. The kale and leeks you want to eat in January need to be close to full size by the end of October. After that your garden works more like a refrigerator than a factory. So the equinox is not the end of the season. It is the last deadline of it.

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Bring in the harvest

Pick the last warm season crops now: tomatoes, peppers, cucumbers, beans and squash. The nights are getting cool, and those plants have mostly stopped ripening new fruit anyway. Basil goes first. It starts to suffer as soon as nights drop below 50°F, and after a few of those it turns black fast. Tomatoes with even a little color will finish ripening on the kitchen counter. Fully green ones are better in a chutney.

This is also the week to save seed from your favorite plants. Beans and peas are the easiest, because you just let a few pods dry on the plant and shell them. For tomatoes, scoop the seeds into a jar with a little water, let them sit for a few days until they get a smelly film on top, then rinse and dry them on a plate. Only save seed from open pollinated varieties. If the packet said F1, the seeds won't grow into the same plant. Squash is tricky too, because varieties in the same family cross with each other easily, so skip it unless you only grew one kind.

Then fill the pantry. Freeze, dry or can what you can't eat this week. Herbs like oregano, thyme and sage dry beautifully in small bunches hanging in a dry room.

The tomatillos tell you they are done by filling out the husk and splitting a few of them open. That is the only ripeness signal you get, so pick them now and stop waiting for a color change.

Plant for winter, and what can wait

A lot of equinox lists tell you to plant garlic now. Not in Seattle. Our soil is still warm in September, and garlic planted this early grows too much leaf before winter. Plant it from mid October to mid November. Use this week to buy your seed garlic, because the good varieties sell out, and get the bed ready with compost.

It is too late to start kale or chard from seed for a winter harvest here. If you have transplants, they can still go in this week and will give you a small harvest now and a bigger one in spring. From seed, spinach, mâche, arugula and loose leaf lettuce still work. They grow slowly through the fall, sit quietly through winter, and take off again in February. A row cover makes a big difference for all of them.

Any bed that is coming empty should get a cover crop. Crimson clover and fava are my favorites, and cereal rye still works into October. I wrote more about cover crops in Seattle last week.

Fall is also a good time to divide perennial herbs. Chives, oregano and thyme that have grown into big clumps can be dug up, split into pieces, and replanted. Give the extra pieces to a neighbor who doesn't grow food yet. That is the best kind of harvest gift.

Clean up, but not too much

Pull the spent summer plants, but cut them off at the soil line and leave the roots in the ground. The roots hold the soil together through our winter rain and feed the soil life as they break down.

Pick up fallen fruit and remove anything diseased, like tomato leaves with blight or squash leaves covered in powdery mildew. Those go in the city yard waste bin, not your home compost, because a backyard pile rarely gets hot enough to kill disease. Healthy plant material goes on the compost pile.

Don't leave your soil bare. In October, fallen leaves make a free mulch for beds and around perennial herbs and berries. A few inches is enough, and keep it off the stems. This is also the time for slow amendments, not fertilizer. I explained why in When to fertilize vegetables in Seattle, and when to stop.

Cleared, fed, and covered. Straw for now, fallen leaves in October. Bare soil in a Seattle winter just washes away.

Your fall equinox checklist

• Pick the last basil, tomatoes and peppers

• Save seed from one favorite open pollinated plant

• Buy seed garlic and prepare the bed with compost

• Sow spinach, mâche or arugula

• Sow a cover crop in every empty bed

• Divide crowded chives, oregano and thyme

• Cut spent plants at the soil line and leave the roots

• Find your row cover and cloches before the first cold night

Whatever you call this day, give yourself a quiet moment in the garden this week. Think about what worked this summer and what didn't, write it down while you still remember, and then just breathe. The fall jobs will still be there tomorrow.

Our first frost usually doesn't come until November, but it never sends a warning. My Seattle Fall Garden Guide has frost dates for Seattle, Portland and the Willamette Valley, plus a full section on protecting what is still growing and extending your harvest into winter.

Get the Seattle Fall Garden Guide

And if you would rather see a fall garden in person, Walk My Garden With Me is on Saturday, October 10, from 1 pm to 2:30 pm here in Phinney Ridge. It is free, small on purpose, and there is no pitch at the end.

Happy fall equinox. Let me know if you need help with your garden. I am here for you.

Jackie