Growing Rosemary Indoors | Common Problems

If you brought your potted rosemary plant inside before hard frost, it’s most likely installed next to a sunny window. It’s worth keeping rosemary over the winter because every year they will grow larger and more robust during the summer months. And every time you pick a fresh sprig of rosemary, the fragrance will instantly transport you back to the growing season. Growing rosemary indoors for a few months is certainly possible, but there are a few common problems to watch out for. Read on to learn more, and you’ll soon have the pleasure of adding fresh rosemary to your cooking all winter long.

GROWING ROSEMARY INDOORS | COMMON PROBLEMS

POWDERY MILDEW

Rosemary can be prone to a fungal condition called powdery mildew indoors. Sometimes it’s hard to see when the fungus first appears since rosemary is a pale green to begin with. Look at the plant closely once a week to see if there is a light gray, powdery growth on the leaves.

Powdery mildew often starts on the fresh, new growth that rosemary produces in the winter. This growth tends to be weak since light levels are lower indoors, and it’s often thin and scraggly. One way to help control powdery mildew when growing rosemary indoors is to cut this new, weaker growth off the plant as it appears. Use these sprigs in cooking. The plant will put out more new growth next summer when it’s back outdoors.

If the mildew appears on the older foliage, first take the plant to the kitchen sink and wash the plant with hard stream of water from the spray attachment. After the plant is dry, spray with one of the organic fungicides available at your local garden center. Note that although neem is labeled as a fungicide, most gardeners have not had good luck with it for mildew control. There are other organic fungicides that are more effective and will still allow you to eat the herb.

DRYING OUT

The main reason that rosemary plants die over the winter is that they dry out. This plant is quite drought tolerant when planted in the ground because of its large deep root system. But in a container that congestion of roots fills the pot and makes it difficult to keep the plant well hydrated.

When growing rosemary indoors, place the pot in a fairly deep saucer so that you can water the plant thoroughly without being afraid that the excess will overflow onto the floor. After watering, let the pot sit in the saucer full of water for an hour or so, and then remove the excess water with a towel or a turkey baster. Rosemary growing in a warm house by a sunny window might need watering every three or four days. Check your plant by feeling the soil, learning the difference in weight between the dry pot and a well watered one, and watch for wilting on the top growth.

LACK OF LIGHT

Some varieties of rosemary are especially sensitive to short hours of daylight. Nights are long at this time of year and there is even less light indoors. When growing rosemary indoors, keep your plant in the sunniest place you have. If the plant starts dropping leaves, consider supplementing the natural light with a full-spectrum plant light.

If you have lost rosemary plants in the past due to lack of light, look for the variety called ‘Salem’ next spring. This cultivar of Rosmarinus officinalis is less sensitive to short days, and so it’s easier to keep indoors over the winter.

Have you ever tried growing rosemary indoors?