Rosemary is a beautiful evergreen herb that can grow as large as a hedge in warmer climate zones (8 and above). This herb is a member of the Labiatae, or mint, family and is known for its pine-needle-like leaves and distinct, fresh fragrance. In addition to being grown for its savory leaves, this plant also produces beautiful light blue flowers that make it a common addition to ornamental gardens. Although this plant’s woody stems and tough leaves allow it to temporarily survive in temperatures as low as 0°F, if you are located in USDA Zone 7 or lower, try growing this herb in a pot and move indoors in the winter for use all year round.
Tuscan Blue rosemary is an imposing variety, growing between 6–7′ if not pruned back. Tuscan Blue will reach these epic heights when grown outdoors in USDA Zones 8–10 but’ll likely only reach 1–4′ when grown in cooler regions. This vertical-tending plant sometimes likes to branch out in a more globular fashion, so leave plants about 1–3′ of space on all sides to allow enough room to thrive. Tuscan Blue is a popular variety in the kitchen thanks to its lovely fragrance and soft taste.
Seed Depth: 1/4–1/2″
Space Between Plants: 1–1.5′
Space Between Rows: 2–3′
Germination Soil Temperature: 60–70°F
Days for Germination: 14–25
Sow Indoors: 8 to 10 weeks before average last frost date. Sow multiple seeds in trays and/or pots as they tend to have a low germination rate. Transplant seedlings outdoors approximately 2 weeks after the average last frost date to an area that receives full sun.
Sow Outdoors: Not recommended.
Vegetative: Propagates nicely via stem cuttings. To grow from cuttings, take new growth, 4–5″ in height, from a parent plant. Remove the lower leaves and place directly into well-drained soil or soilless mix.
As this plant is native to the Mediterranean region, it can withstand short cold snaps but will die if left outdoors in temperatures under 30°F for longer than a few days. As such, if you live in USDA Zone 7 or lower, plants should be grown in pots that can be moved indoors or, at the very least, be heavily mulched in the fall for protection throughout the winter.
Natural: When starting indoors, rosemary prefers partial sun. Place in full sun when transplanting outdoors for at least 6 hours a day.
Artificial: Starts grow well under standard fluorescent bulbs. Place bulbs about 3″ from the top of your plants to avoid burning. If using bulbs with a higher intensity than fluorescent, place bulbs a minimum of 2′ above plant tops.
Soil: Prefers sandy and even slightly rocky soil that drains well. A pH of 6.0 to 8.5 will allow your plant to grow, but a range of 6.0 to 7.5 is best.
Soilless: Will grow well in most soilless mixes but prefers those that contain perlite, vermiculite, and/or coco peat.
Hydroponics: Can grow in a hydroponic system such as NFT. Be aware that rosemary grows slowly in hydroponic systems.
Aeroponics: Will thrive in an aeroponic system.
Water: Requires low to moderate levels of water. Soil can be relatively dry between waterings, but do not allow to dry out completely for more than a couple days at a time.
Nutrients: Sources differ on the level of fertilization that rosemary needs to prosper, with some suggesting not fertilizing at all and others recommending a weekly application of nitrogen. If you are experiencing stunted growth, try applying a small amount of nitrogen-rich fertilizer and increase or decrease applications based on results.
Foliar: A foliar spray of liquid seaweed can be beneficial but is not necessary.
Pruning: Trim main sprigs when young to encourage bushy growth, leading to higher overall yield. Remove any dead stems and make sure to give the plant a good trimming after flowering.
Mulching: Lightly mulch the base of the plant to lock in moisture during dry summers and retain heat in cold winters. If attempting to overwinter in Zones 7 or lower, apply straw or another organic material around the base of the plant to help it stay warm.
Companions: Grows well with broccoli, cabbage, beans, and sage. Avoid planting with basil, potatoes, and pumpkins.
Harvest: May be harvested approximately six to eight weeks after planting. As plants have the highest oil content just prior to flowering, this is a great time to harvest after your initial picking. Avoid trimming more than 1/3 of the plant at a time and cutting sprigs that have a “woody” appearance: this will damage the plant. Harvest sprigs by clipping with scissors.
Storage: Sprigs of rosemary can be kept in a plastic bag in the refrigerator for up to a couple weeks.
Fun Fact: The ancient Greeks believed that rosemary could help with retaining memories and would wear sprigs of the herb around their necks and in their clothes. Now, if only we could remember where we heard that…
Preserve: Sprigs of rosemary will dry exceptionally well. Simply hang upside down in bunches in a dry place until the leaves come off easily. Store in a container in a dry location. Rosemary may also be kept in oil. Simply remove sprigs from stem, chop, place in oil in a tray, and freeze.
Prepare: Add rosemary as an aromatic flavor to any soup or stew. This herb is also a great addition to roasting vegetables or potatoes.
Nutritional: This herb possesses a decent amount of the minerals calcium, magnesium, and potassium as well as vitamin(s) A and C.
Medicinal: Rosemary has been used since the time of the ancient Romans to ease ailments ranging from preventing miscarriages to treating a blocked urinary tract. Although most of these claims have not been verified, some current studies have indicated some truth to the assertion that it can assist in easing many stomach ailments such as indigestion and heartburn.
Warnings: While eating the plant in most quantities is safe, consuming the oil is not recommended.
Most folks associate rosemary with meat dishes like pork or braised beef, but this herb has so much more to offer! Take, for example, this Ginger and Rosemary Summertime Cocktail that’s fresh and delicious: the perfect thing to sip on on a hot summer’s day.