In from the cold

The sweet scents of the spring and summer garden have been replaced by the earthy smell of fall foliage and moist dirt. Soon that too will be gone, replaced by the tangy odor of frozen ground and fresh snow. Winter is a long season. If you have spent any time here during that season, you know how the smell of fresh green anything can perk up a blah day. People go to great lengths to find fragrant flowers or plants just to sniff them. Like the guy I saw at Costco last winter just smelling the roses. When it comes down to those long, cold, late January and February days, though, nothing beats a few pots of fragrant herbs to perk up our senses and remind us that winter will end, and we can survive until it does. This is even truer when the herbs are included in a hearty stew or winter salad. The biggest challenges to growing an indoor herb garden are providing enough bright light, humidity and nutrients. Many herbs need much more light than you’d think, to produce abundant leaves and develop their maximum flavor or aroma. Sunny, south-facing window sills are best for herbs, but those spots are also best for other indoor plants. Even the south-facing window may not be good enough: Our winter sun is so low in the sky that its intensity is only about half what it is at the height of summer. On top of that, it is only up about eight to

ten hours a day; half what it is in the summer. So if you throw in more than a few gray cloudy days, it’s not difficult to understand why many indoor plants get really cranky and pout by not growing and turning yellow.

“It helps to have supplemental light in the winter even if it’s just grow spots or four-foot fluorescent grow lights,” says Patricia Mattson, owner of the Herb Garden in the Spokane Valley. A bank of two or more lights hung side-by-side and fitted with high quality cool white tubes or grow lights are all that is needed to augment the available natural winter light.

The light fixtures should be hung so they can be raised or lowered to stay within a few inches of the tops of the plants. A timer should be added and set to provide about 15 hours of light a day. “Anything to help them keep producing leaves and growing,” says Mattson.

Warm but not too hot

Temperature is important to good vigorous growth as well. Herbs like the sages, thymes and oreganos need 60 to 70 degrees during the day and the high 50s at night. Others, like rosemary and basil, need close to 70 during the day and nothing below the high 50s at night. These temperatures are well within normal house temperatures, but remember to make sure plants are placed out of drafts from opening doors, heat vents and registers.

Some plants like rosemary are prone to mildew if they don’t have good circulation, so allow air to circulate around plants freely. You can also group herbs together, in their pots, on a bed of gravel created on a tray or cookie sheet, then keep the gravel full of water to raise the humidity around the plants.

It’s not too late

If you have herb plants in your garden you’d like to bring in, there is still time to dig and pot them up. Choose smaller plants over larger ones because it’s easier to dig enough roots and the plant will adapt more quickly. Use pots that are one to two inches bigger than your plant and deep enough to allow for root development. If the pot is too small, the plant will not have room to grow, and it will be difficult to keep it watered. If the pot is too large, many herbs actually go into a shock that is hard to break them out of. Fill the pots with a quality rich potting mix that holds water but drains easily. “Do a diluted fertilizer every couple of weeks,” advises Mattson.

Herbaceous herbs like chives, thymes and oreganos and other non-woody plants can be divided with a sharp shovel. Be sure to dig out a large enough piece of root and fill the hole it came out of. Chives should be allowed to stay outdoors until the first frost kills the top growth. Cut the dead sprigs back, and bring the plant indoors where new growth will sprout soon.

While most herbs are fairly immune to bug and disease problems, check the plants carefully for bugs and signs of disease. “Swish the plants through some soapy water or an insecticidal soap mixture before you bring them in,” says Mattson.

Plants being brought in from outdoors need to transition to the warmer house temperature and lower light levels gradually. Once you have your plants dug and repotted, put them somewhere that is a little warmer and shadier than outdoors. A good place might be a garage or a very cool spare room under grow lights for a week or two before they are moved to their final spot. This is also a good time to watch for bugs that you missed on the initial inspection.

One popular herb that needs some special attention is rosemary. While there are a few cultivars (Madeline Hill for one) that are supposedly hardy to minus 15 degrees, most of the ones found on the market here are not. Some of them can’t even survive temperatures below 20 degrees.

Rosemary benefits from being kept in a pot year-round. The pot can be sunk into the garden during the summer and very easily pulled out and transitioned into the house. Mattson’s experience is that rosemary likes it a little warmer than most herbs. She lets it get a little on the dry side but not completely dry before she waters and then not sopping wet. She finds, “a good location and half-way ignores them.”

There is one last reason for creating an indoor herb garden. It just might be all we need to keep our sanity until spring comes again.