Rosemary is an evergreen shrub with narrow, pointed leaves. It has been in use since the time of the Ancient Greeks. Rosemary is an excellent seasoning for lamb, pork, and chicken, and you can use it to make flavored olive oil. One affordable way to have a regular supply of rosemary is to cultivate it yourself. Rosemary is relatively easy to grow, even if your soil is not of the highest quality.
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How to grow rosemary
Grow rosemary using one of these methods: from seeds, from stem cuttings, or from purchased seedlings. For indoor planting, you can use a hydroponics system where the rosemary is grown in water with no soil, or you can plant the herb in containers.
Start seeds for indoor or outdoor planting indoors
For outdoor plants, do this 10 weeks before the last frost in your US Department of Agriculture hardiness zone. Sprout the seeds in a container mostly filled with soil formulated for starting seeds, also known as starting mixture. The seeds should germinate within two weeks.
Grow your rosemary from cuttings (AKA propagation)
Cut healthy sprigs without flowers on them. Ideally, these sprigs should be around six inches long and be a little woody. You should take cuttings when the weather is on the cooler side, though it can be done at any time in the growing season.
Remove the leaves from the bottom two inches of the sprig and cut the bottom at a 45-degree angle to maximize exposure to the soil. Dip the stem in growth hormone and plant in potting soil that drains well. It is best to keep the rosemary in a warm and humid location but even under ideal conditions, it may take as long as eight weeks before you start seeing signs of growth. Note also that it can take up to a year before you will be able to harvest sprigs.
How big of a pot do you need for rosemary?
The ideal container for growing rosemary should measure around 8 inches deep and 12 inches across.
How much sunlight does rosemary need?
Provide your rosemary plants with at least 6 hours of sunlight every day, whether you grow them from seeds, seedlings, or cuttings. Because of this plant’s need for sunlight, growing it indoors can be tricky. Lack of sunlight is one of the main reasons rosemary plants die and is likely to be one of the big obstacles to them thriving indoors.
Before moving a rosemary plant inside, get it used to limited sunlight by gradually moving it to shadier and shadier locations. Bringing it in from a sunny spot without getting it acclimatized is likely to kill it, since it needs to become more efficient at using light to create energy, which takes time.
How often should you water rosemary?
Water indoor or outdoor rosemary plants only when the soil’s surface is dry. Watering too much or too little kills rosemary plants even faster than keeping them in the shade.
Note on growing rosemary indoors
Keep indoor rosemary plants in locations with moving air. Rosemary plants need good air circulation around the leaves whether they are indoor or outdoor plants, but this is likely to be more of a problem for indoor plants. Poor air circulation often leads to plants developing powdery mildew, which can kill them.
Harvest rosemary by cutting sprigs from the plant, preferably during spring and summer, since it grows most actively in these seasons. Harvest in the morning before temperatures rise. Take cuttings from large plants regularly, as this can help them become even bushier. If you plan to dry the sprigs, wait until just before the plants start blooming, since this is when their oil content is greatest.