Southern California gardeners wait anxiously for summer because of the amount of produce they can grow, but some plants with a reputation for being summer-friendly are better suited to this region’s cooler winters.
Experts say now is a great time to plant many annual herb plants and it’s also the time to perform some much-needed maintenance on perennial herbs.
“This is a really unique time, sort of a small window of time to get some fun herbs that you typically wouldn’t be able to get growing in hotter times of the year,” said Aaron Fox, associate professor of urban and community agriculture at Cal Poly Pomona’s Huntley College of Agriculture.
Annual herbs
Fox said he frequently hears from gardeners that their cilantro bolted – meaning it went to seed – soon after being planted in summer gardens and that’s because they don’t realize how delicate the herb is. Similarly, Fox said that herbs such as dill, tarragon, chervil and mint are more likely to thrive in cooler weather.
He said that, unlike Mediterranean-adapted herbs such as rosemary and oregano that can withstand poor soil and limited water, these winter herbs need nutrient-rich soil and regular watering. Ideally, Southern California should receive a lot of rain this winter to keep them happy.
“But if not, they’re not drought-adapted, so they need a little more TLC,” Fox said. He recommends sticking your finger into the soil, which should feel moist but not wet. If the soil is dry, it’s time to give the herbs some supplemental water.
Fox also recommends planting herb plants rather than trying to germinate herbs from seed. The same cool weather that will keep the herbs from bolting also makes it less likely that seeds will germinate if planted outdoors.
Gardeners should also expect that because it’s cooler out, these plants will establish themselves and grow more slowly than they would during the summer, Fox said.
Johnny Wilson, one of the farmers at the Ecology Center – a 28-acre organic farm and education center in San Juan Capistrano – recommends providing the herbs with a balanced organic fertilizer at least once a month.
Wilson said it’s important to watch the plants to make sure they don’t get too large, as this can be a precursor to bolting.
“If they’re getting too big, even if you’re not going to harvest them, you still want to cut them back, to keep that tender growth coming,” Wilson said.
Perennial Maintenance
Wilson said wintertime is a good time to cut back some of those Mediterranean herbs that grow in Southern California year-round. That includes things such as the aforementioned rosemary and oregano, but also sage, lavender and lemon verbena. He said gardeners should look to trim the “three Ds,” which he said stands for dead, diseased or disoriented wood and branches.
Wilson also recommends working some organic compost into the soil around some of these Mediterranean herbs, but with a caveat: Because these plants don’t like super-rich soil, gardeners should add in the compost sparingly.
He recommends talking about a handful of compost and working it into the soil around each plant before adding some mulch around the plants.
Following these steps will help to ensure a flush of new growth on the plants come spring, according to Wilson.
Looking ahead
The cool weather won’t last forever and as temperatures climb, gardeners will have to make adjustments to keep their annual herb plants viable.
Wilson recommends increasing watering as the weather dries up to make sure the soil is moist and suggests putting in more compost around April or May.
Fox said that gardeners can mitigate some of the sun and heat of the summer by planting their herbs in a spot that will have more shade come summer. He suggests planting them under something like a deciduous tree or grapevine. He said that as these things start leafing out they may provide the herbs with some shade.
There’s only so much you can do in the long-term though, according to Fox.
“You can shade them, you can maybe water them a little more, but at some point, I would say, you’re going to have to let them go,” he said. “And that’s fine. I think it makes them special; it makes them have a distinctive season.”
Summer doesn’t mean an end to all annual herbs. Some herbs are still best suited to that season.
Fox says to wait until the summer to grow basil.
He said it is possible to grow basil in the winter, especially if it’s already been established, but basil just generally tends to look sad and perform worse when it’s cool.
“Also, that basil flavor just works so much better with other things like tomatoes, so I say give your basil a break and try some different things, like tarragon,” Fox said.
