In the Pacific Northwest, we’ve just crossed that magical June 1 threshold into the warm season. (Yay!) In theory, June 1 provides an indicator as to when we can begin planting out our sensitive warm-season crops, like peppers, eggplants, beans, basil, corn, cucumbers, squash, and tomatoes, because, heck, summer is just around the corner. In the midst of this torrential downpour, summer couldn’t feel further away, but I know it’s coming. Anytime now. Please.
So we’ve officially entered the “warm season.” But what does that mean?
Cool versus warm season crops
Vegetable crops are either cool season or warm season. Cool season crops thrive in the cool and damp of spring and/or fall, while warm season crops thrive in the heat of summer. You can find a list of common cool and warm season edibles at the end of this post.
Now’s the time to sow or plant out all those sensitive warm-season crops mentioned above. It’s their time to shine.
But that doesn’t mean you have to immediately stop planting cool-season crops like beets, lettuce, and carrots.
Bolting, and how to avoid it
The major hurdle to growing cool-season crops in the summer is the risk of bolting. Bolting is a term to describe what happens when the plant decides its work here is done and it’s high time to start making some babies. It sends out a talk stalk of flowers and stops producing the leaves or root that we want from it. When that happens, the plant is generally past its best-before date. It may not be inedible, but often it will taste bitter, or tough. So obviously, we want to prevent our plants from bolting, which can be hard to do during summer heat waves.
Many cool-season crops are prone to bolting. Lettuces and other salad greens are particular susceptible; arugula and spinach are almost guaranteed to bolt in summer. Beets and radishes are also prone.
The best way to prevent bolting is to make regular sowings, and harvest regularly. That’s because bolting is often triggered by a sudden change in temperature (technically, it’s caused by lengthening daylight hours, but in my experience, temperature fluctuation is the biggest culprit). We can get around that by succession sowing (for example, planting a short row of lettuce, then planting another two or three weeks later) and harvesting regularly. That way, we’re growing in a shorter time period and there’s less chance of the plants being effected by a sudden temperature swing.
Another way to prevent bolting is to provide afternoon shade, or plant in the shade of larger plants. I like to sow lettuce seeds at the same time I transplant my tomatoes, for example, because by the time the tomatoes are large enough to shade the lettuce, the lettuce will appreciate the shade.
You can plant a lot of cool-season crops again in late-July so that they’ll germinate and start to mature once the summer heat has started to wane. This will be your fall and winter crop. I won’t go into a lot of detail about this since this is called “Welcome to the Warm Season,” not, “Winter Gardening 101,” but suffice to say, almost all cool-season crops can be planted in late summer for either harvesting in fall or throughout the winter, or to overwinter and mature the next spring.
One last thing. Before you transplant out your peppers, squash, and other heat-lovers, help them transition into your garden by protecting them with something at night until they get comfortable outside. If they’re small enough, cover them with a glass jar or plastic jug with the bottom cut off, or use a cardboard box if the plant is bigger. Remove it in the morning. Or you can just keep them in their pots for a week or so, and bring the pots indoors at night. Ease them into the garden during the day, putting the pots outside for an hour at a time (in the shade, to start). Each day, leave them outside a little longer, until they’re spending all day outside. Then bite the bullet and plant them. This little exercise will help reduce “transplant shock.”
Should I direct seed or transplant this vegetable?
- DS=Direct seed
- T= Transplant
- DS/T=Direct seed or transplant
Cool Season Crops
Asian greens (DS)
Broad beans (DS)
Brussels sprouts (T)
Chinese cabbage (T)
Swiss chard (DS)
Warm Season Crops
Soy beans (DS)