Answer: One of the most popular herbs to grow indoors is rosemary. To keep your plant thriving, put your rosemary plant in your sunniest window and allow it to dry out between waterings until it almost wilts. Don't water or mist the plant when the weather is overcast. Without sun, the plant can't use the water and could drown. If the plant is suffocating from too much water, the leaves or leaf tips will turn brown and fall off -- let the pot dry out.
Rosemary is happiest when grown in a soilless mix, which is a composition of vermiculite, perlite and coarse peat. In the wild, it can tolerate a wide range of pH and moisture conditions, but it must have excellent drainage. This can be best accomplished when the plant is grown in a clay pot year-round. Clay permits faster evaporation of water, thus aiding in quick drainage. Year-round container growth also eliminates the need to transplant the rosemary into ordinary garden soil for the summer. During the active growing season, place the container in full sun, water only when the growing medium is dry and fertilize with a dilute 20-20-20 solution every two weeks. Rosemary benefits from frequent snipping or pruning, whether grown as a topiary or simply as a small herb.
To acclimate rosemary to indoor conditions in the fall, place the pot in partial shade for one week beginning September 1. Bring the pot indoors to a full sun location before you turn on indoor heat. Most problems with rosemary develop over the winter months. Low light or high temperatures produce leggy, woody growth. Fungal problems arise when the plant is overwatered, overcrowded or grown with little air circulation. Some gardeners change the growing medium to a cactus mix over the winter or spread an inch or two of pea gravel or sand over the top of the soil to encourage rapid evaporation.
I'd repot the plant to eliminate the insects in the soil, then place the plant in the sunniest spot available and wait for it to recover. Good luck with your plant!
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