Moving herbs indoors

In a mild winter areas, perennial herbs, that naturally overwinter outdoors, such as rosemary, lavender, oregano, and thyme, can be harvested as you need them all winter long.

The fresh herb picking season can be extended by months by bringing the plants in when frost threatens. This technique works best for perennial and biennial herbs, such as chives, mint, oregano, thyme, parsley, and rosemary.

Annual herbs, such as basil, tend to tire after a few weeks indoors. Annual herbs are best started from seed indoors under grow lights and grown as new plants for a winter harvest.

Pots of basil moved inside prior to first frost

Teapot of thyme
Large twig basket filled with different mints.
If left to overwinter in the garde, mint can become invasive,
bo relegating it to pots has become our standard practice.
Fairy surrounded by basil & parsley

Some tips for bringing herbs indoors successfully:

  • Select the healthiest herb plants.. Small to medium-sized plants will survive better because the digging and transplanting process will destroy many roots.
  • Don’t bother bringing in tough perennial culinary herbs whose dried leaves have good flavor — sage, oregano and thyme — unless you think you can’t get along without the fresh leaves.
  • Check plants for any signs of insect activity and spray with an organic insecticidal soap, before moving them indoors.
  • Water plants well and dig up herb plants in the garden on a cool, cloudy day. 
  • Select a container large enough to accommodate a plant’s root ball, allowing room for growth. 
  • Leave some garden soil on the plant’s root ball.  Potted plants need a faster-draining medium than straight garden soil. But don’t like to stress the roots by removing all the soil.
  • Mix up a porous potting medium of peat moss, coarse vermiculite, perlite and compost to fill the space in the pots not occupied by the roots and the soil clinging to them. Set the root ball on top of the soil; fill in around it with the potting mix. 
  • Place these newly transplanted herb plants in a shady spot to adjust to the transplanting for 1 to 2 weeks. Keep them protected from winds and cold temperatures.  
  • Before a frost, bring the herb plants indoors and place them in a sunny, south-facing window.  Help plants acclimate to life indoors and thrive during winter by placing them in a window that receives at least six hours of sun daily. 
  • Pinch off the tips of stems periodically to stimulate lush growth.
  • Check for any insects that have hitched a ride indoors on your plants. Flush the soil with water and rinse off the foliage, using a blast of water from the garden hose to chase away any pests
  • Water sparingly, when the soil feels dry,  and don’t fertilize. 
  • Provide both humidity (by placing plants on a tray of damp pebbles) and good air circulation (you may need a fan).  Or mist the air around plants once a week to boost the humidity level.
  • Keep herbs above 55°F at night and 65°F to 70°F during the day.
  • Most herbs will grow slowly, or not at all, indoors in winter. Harvest what you need, but leave some leaves for the plant to survive. Plants rebound come late winter when the stronger light levels and longer days return.  When new growth appears, start fertilizing the plants occasionally with a diluted solution of soluble fertilizer.
  • Come spring, if you’ve been successful overwintering some of your herbs, once all danger of frost has passed, move your perennial herb plants back outside. Repot them into pots with fresh potting soil, or transplant them into the garden. They will bounce back and start putting on new growth 
Some tips for specific herbs:
  • Lemongrass, ginger, bay, rosemary, scented geranium, and lemon verbena, for example, require protection from cold weather to survive. Also bring in lavender, tricolor sage, pineapple sage, and heliotrope.
  • Parsley, a  biennial herb, will survive the winter only to send up a flower stalk in spring and then die. Pick all the parsley you want and compost the plant when you’re done.
  • Rosemary has special needs to survive. It likes cool temperatures (50- to 60-degree F), high humidity, and barely moist soil in winter. Water the pot just enough to keep the soil from drying out. Constantly wet soil damages rosemary’s roots. Instead, mist frequently around the plant to help raise the humidity level and also help deter red spider mites, which are the bane of rosemary grown indoors.
  • Pineapple sage that is too tall and broad for  your sunny window, can be saved by taking cuttings. Strip lower leaves from the stem, both to prevent belowground rot and to encourage rooting. Clip large leaves to reduce the surface area from which moisture is lost. Make a hole in the rooting medium (equal parts peat moss, coarse vermiculite, perlite and compost) with a pencil or chopstick, then stick the stem into the hole so that it doesn’t quite touch the bottom of the pot. equal parts peat moss, coarse vermiculite, perlite and compost. Firm the soil around the stem. To minimize moisture loss, set a stiff plastic freezer bag loosely over the pot to form a tent. Place the pot near the window but out of direct sunlight. Condensation inside the bag is a sign of too much sun and/or insufficient circulation. An alternative to this tent method is hand-misting the cutting several times a day. By the end of two weeks, pineapple sage cuttings will have formed roots. (Other herbs may take four weeks or longer.) Visible top growth indicates that roots have formed. Even though the new roots will now take up moisture on their own, remove the tent or discontinue misting gradually over a few days so as not to shock the plant. 
  • Try using a light to supplement waing sunlight. Few windowsills, no matter how sunny, provide enough light for your herbs. And in cold-winter climates, the sill can be quite chilly. 
  • If you can’t use a light, try chives, winter savory, mint, bay, lemon balm, thyme, and rosemary—they’re better at tolerating indirect light.