A handful of basil from the summer garden is long gone by mid-November, yet the stuffing pan, the soup pot and the Sunday roast still want something green and fresh. University of Illinois Extension has a ready answer for the cold months: a short list of herbs that keep growing on an indoor sill.
The Illinois Extension release, dated Oct. 23, 2023 and written by horticulture educator Christopher Enroth, names basil, chives, oregano, thyme, winter savory, rosemary, parsley, sage and mint as the 9 herbs that do well indoors. Enroth ties success to two limits, light and humidity, so the rest of this list follows the light, the pots and dry air first, then the herbs one by one.
Six to Eight Hours of Bright Light Sets the Schedule
Illinois Extension says herbs need about 6 to 8 hours of bright light a day, and a south-facing window works well. Winter sun is weaker and shorter, so lamps have to run longer. The release puts the ratio at roughly 2 hours of supplemental light for every 1 hour of natural light, adding up to 12 to 16 hours a day on an automatic timer.
Other extension offices land in the same range. Iowa State Extension says grow lights belong 6 to 12 inches from the leaves. Penn State Extension, in a guide updated Nov. 1, 2024, describes 14 to 16 hours under two 40-watt cool white fluorescent bulbs. Illinois also advises rotating pots every few days so plants grow evenly instead of leaning toward the glass.
Counter space gets scarce in holiday week, and craftingyourhome.com has a list of 8 things that do not belong on a kitchen counter for anyone clearing room near the window.
Pots, Feeding and Dry Winter Air
Illinois calls for containers with drainage holes and good-quality potting mix, never garden soil. Iowa State recommends clay or terracotta because it is porous and dries faster, and warns that oversized pots stay wet too long.
Feeding is a split. Illinois and Penn State both say to use a water-soluble fertilizer every 2 weeks and no more often, because extra can harm flavor and aroma. Iowa State advises half or quarter strength and skipping winter altogether.
Temperature has a ceiling and a floor. Illinois says to keep rooms at 70 degrees F or below and away from heat sources, while Penn State gives 65 to 70 degrees F by day and 55 to 60 degrees F at night. Heating dries indoor air, so Illinois suggests grouping plants, running a humidifier nearby or growing herbs in an enclosure. Frenz Hub’s 9 Best Humidifier for Plants guide covers that last option, and anyone leaving town for the holiday can pair a watering check with craftingyourhome.com’s 8 things never to do before leaving home for Thanksgiving.
One herb that is not on the Illinois list deserves a note in homes with animals. Penn State says tarragon is toxic to dogs and cats and should be avoided in households with pets, and Frenz Hub keeps a list of 8 cat-safe plants for that kitchen.
Basil, Chives and Parsley Cover the Soft-Leaf Side
Basil is the one most likely to sulk. Wikipedia describes it as native to tropical regions from Central Africa to Southeast Asia and sensitive to cold. Penn State says basil cannot tolerate temperatures below 50 degrees F, so it should stay off a chilly ledge, and its potting mix should never dry out completely.
Chives are easier. They belong to the same genus as onions and garlic, and Wikipedia notes that the hollow leaves give a mild onion flavor to omelettes, potatoes and soups. Penn State lists chives among the herbs that tolerate lower light, in the range of 2 to 6 hours of direct sun. Snipped over eggs or potatoes, they pair with the small shortcuts in Frenz Hub’s roundup of 20 clever kitchen tricks for home cooks.
Parsley rounds out the group. According to Wikipedia, flat-leaf (Italian) parsley is easier to grow, and chefs often prefer it for stronger flavor, while curly parsley is mostly a garnish, though the page notes that preference is disputed.
Rosemary, Thyme, Sage and Oregano Want Sun and Dry Spells
These four come from Mediterranean ground, and they behave that way in a pot. Penn State says rosemary and thyme prefer direct sun, and that rosemary, thyme, sage and oregano should dry slightly between waterings.
Extension offices do not agree on how easy the group is. Illinois lists all four as herbs that do well indoors. Iowa State puts thyme and oregano among the easiest indoor herbs but calls rosemary and sage harder, citing higher light needs and pests such as spider mites.
The payoff is in the kitchen. Wikipedia says sage and onion stuffing is a traditional side for roast turkey at Thanksgiving, and thyme is a key ingredient in bouquet garni. Rosemary stays evergreen and flavors stews, stuffing and roasted meats, according to its Wikipedia entry. Dried oregano, Wikipedia adds, is more intense than fresh.
Mint and Winter Savory Finish the List, Plus a 3-to-1 Swap
Mint needs its own pot. Wikipedia describes mints as fast-growing perennials that spread by runners and says tubs keep them contained. Iowa State gives the same advice in general terms: grow each herb species in a separate container. Mint leaves flavor teas, syrups, sauces and jelly.
Winter savory is the least familiar of the 9. Wikipedia says it is strong when uncooked, loses much of its flavor with long cooking and pairs well with beans and lighter meats such as chicken or turkey. Outdoors it is hardy to USDA Zone 4.
Fresh herbs can stand in for dried ones. Illinois says to harvest herbs as needed and notes that indoor herbs usually grow more slowly than outdoor ones in summer. Its substitution rule is 1 tablespoon of fresh herbs for 1 teaspoon of dried. For a steady winter supply, the release suggests drying herbs in summer or growing more of them indoors once the weather turns cold.
Iowa State adds a pruning rule: perennials such as chives, mint, oregano and thyme should lose only the top third of growth at a time.
This article was produced with AI assistance and edited for accuracy against the sources linked above.
Image: Peachyeung316 – CC BY-SA 4.0/Wikimedia Commons
