Great tips to grow herbs in containers

Here are tips from Cox and Creasy for filling window boxes or patio pots with herbs.

Grouping: Combine plants that need the same amount of water and fertilizer, Creasy says. Plant drought-tolerant Mediterranean herbs such as oregano, rosemary, thyme and marjoram in one container, and herbs that need more water and fertilizer (say, parsley, basil, cilantro, chervil) in another.

Size things up: “Genovese basil can grow to 2 1/2 feet tall. You put that in a window box, it’s not going to look very good,” Cox says. “If you’re going to put herbs that tend to grow tall in a window box, keep pinching them back.”

Shopping savvy: Buy healthy plants in good-size pots, Cox says; avoid the leggy ones. Too much top and too little pot means the herb has been watered with liquid fertilizer, he says, “so (it) hasn’t needed to grow a lot of root system and put its energy into growing a large top.” The plant won’t have the root strength to sustain itself.

Container choices: Use containers that have good drainage (holes on the bottom are a must, for starters). Cox puts a plastic tray in the bottom of a window box with drainage holes, then layers in some stone or gravel.

“When you water, the water isn’t just running through and putting soil onto the deck or patio.” Also, “don’t set a pot with a drainage hole directly on a deck. The water can stain.”

Paint the exterior and interior of wooden containers; if you don’t, they will eventually rot after a few years, Cox says. Or line your pot with plastic and pierce it for drainage.

Clay, such as terra cotta, won’t rot, Cox notes, but remember that its substantial weight can make it difficult to move. If you’re putting terra cotta pots in a window box, you’ll need to provide a sturdy frame to connect the window box to the house.

Soil matters: Choose a good-quality, fast-draining soil, Creasy advises. It needs to be lightweight in a window box, but that’s also practical for containers you’ll be moving around a patio. She recommends that the soil have a water-holding medium; these may be pricier, but they are more practical in the long run.

Room to grow: Don’t cram herbs in too tightly, Cox says.

“Give them a little elbowroom because that really translates into root room and a healthier plant,” he says.

Sun and nutrients: Most herbs require full sun, although several (mints, for example) can handle some shade. Pay attention to their growing needs, especially if they will be in one place (like a window box) for the entire season.

Creasy recommends using a good-quality, organic slow-release fertilizer. Because the soil in containers dries out quickly, plants may need daily watering, especially when it’s hot.

Snip away: One of the biggest benefits of growing herbs is that they love to be used — so don’t be afraid to snip them. Herbs in containers especially benefit from constant harvesting, Cox writes, which also keeps plants under control in their restricted space.