The Homeowners Column

The Homeowners Column

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How to keep rosemary happy in winter

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Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

As a UI horticulture educator (oh, these many years) I converse with many exasperated gardeners. From these lamentations certain plants emerge as a communal source of frustration. Yet, gardeners are a gritty group and when we fall in love with a plant we are not quick to cast it aside due to its dogged determination to die on our watch.

I developed a "dead but not forgotten" plant list. Plants that we gardeners really, really want to grow; however, for some cosmic reason we are tangled in a relationship whereby we buy them, they die, we yearn: then we buy again, they die again and we yearn again. Most gardeners give up buying after the third cycle, but the craving continues to plague us.

A few on my list of "dead but not forgotten" plants include: flowering dogwood, blueberries, azaleas and rosemary.

Rosemary is a tasty cooking herb. In the winter rosemary topiaries are popular decorations. Rosemary is fairly easy-going resident outdoors in the summer. The problem, however, is keeping lovely (but somewhat finicky) rosemary happy through the winter.

Rosemary, Rosmarinus officinalis, is a perennial evergreen shrub hardy to zone 7, so she is not winter hardy here. In her native Mediterranean home she can reach 6 feet tall. Containerized rosemary plants can reach a huggable size. Nothing will cheer you quicker on a dull dreary Illinois day than hugging old rosemary. She is the closest thing to catnip for people. One hug and the pungent fragrance of pine will fill the air and you will be compelled to roll on the floor in delight.

Rosemary is best grown in large containers instead of in the ground if the plan is to bring her indoors for the winter. However, most homes are too dry and too warm in the winter to suit rosemary. She likes it cool and moist.

In winter when she is fairly dormant, rosemary needs a cool brightly-lit spot indoors. She is happier if the thermostat is set to 63 to 65 degrees F or lower in a south or west exposure. A garage where the temperature doesn't drop below freezing works well if it includes the presence of plenty of natural or supplemental light.

Rosemary care instructions will often state "let dry between waterings." Good advice to a point since rosemary can suffer if soil remains waterlogged. Remove the foil wrapper with decorated plants and provide a good drainage tray.

In the winter, however, the tags should say, "don't let her dry out." Soil dries quickly in our heated homes. Rosemary is not forgiving if she gets too dry and some branches may die. As soon as the soil dries, it's time to water. I think she does best in a soilless mix and a clay pot.

Rosemary adds fragrance to the home as well as a pleasing flavor to cooking, but use the strong flavor sparingly as an accent. If you like the way the herb smells, you will probably also enjoy the taste. Unfortunately specific cultivars will be hard to find locally during the winter.

Popular cultivars include: 'Arp' (gray foliage, light blue flowers), 'Athens Blue Spire', 'Joyce DiBaggio' (sold as Golden Rain and new growth is streaked with yellow), 'Madalene Hill' (also sold as Hill Hardy). Two good culinary choices include: 'Rexford' and 'Shady Acres'. Some cultivars such as 'Arp' and 'Athens Blue Spire' are reportedly winter hardy here in Illinois. I have not found these to be reliably hardy.

An offering of rosemary signifies love and remembrance, which is not a bad sentiment during the holiday season. Once you understand rosemary's needs, she can be a long-lived companion.

Interested in herbs? University of Illinois Herb Day Saturday, Jan. 23, 2016 at the Wyndham Garden Hotel and Conference Center near Lincoln Avenue and I-74 in Urbana. Online registration For information, contact Linda Harvey (217-244-1693; lharvey@illinois.edu).

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