Q: In late May, I purchased what appeared to be six healthy arugula plants from a garden center. It was my first attempt with this herb. About a week ago, the plants began to flower. Now there are hardly any leaves to harvest, and all the plants have gone to seed. What did I do wrong?
A: Chalk it up to hot weather. Arugula is a cool-season green, and when the temperatures start to heat up to more than 75 degrees, the plants stop producing the edible leaves and go into seed-production mode ("bolting to seed" in gardening lingo).
In our climate, arugula is best planted in early spring (late March to early April at the latest) or in early fall (late September). It's easy to start by direct-seeding it shallowly right into your garden beds. It's also cheaper that way, and your seed pack may last two or three seasons.
If the weather keeps heating up like it's been doing, this is a green that's going to be harder and harder for us to grow for long before it bolts. We may need to move the early-season planting times up even more and the fall planting time back.
For those who have never tried arugula, the small leaves have a bitter and somewhat pungent flavor. They're usually used to add a little kick in a greens mix.