Hill Gardens of Maine - Rosemary - Keeping It Indoors Over Winter

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Rosemary - Growing It Indoors Over Winter
by Fred Davis, MG, Hill Gardens of Maine (To view other articles, click Archives)

Welcome through Fred's Garden Gate. Rosemary, a popular culinary and medicinal herb, is really quite tough. Originally from the Mediterranean, Rosemary likes conditions relatively dry, hot, bright and sheltered from the wind. In a natural habitat (where the soil doesn't freeze), roots extend quite a distance and are accustomed to free-range-foraging for oftentimes sparse nutrients; it does best in a gritty, moderate-humus, well-drained "open" soil....all of which conditions are rarely found in indoor containers.

Over-watering (which encourages soil insects and pathogens — root damage and "rot") is most often the cause of demise, along with accumulation of fertilizer salts in the soil and on the container. Probably the worse thing an indoor gardener can do is to allow containerized specimens to rest in a saucer or tray of water. I like to "flush" at least once a month just before fertilizing. The container is placed in the kitchen sink and water is poured in until it literally gushes from the drain holes. Naturally, the purpose is to dilute and flush out salts...not to blast all the soil away!

Best plan is brightest possible light, restriction of artificial nutrition, and maintaining the plant definitely on the dry side. An organic fertilizer equivalent to 5-5-5 (more or less) applied modestly at 3 to 4 week intervals should suffice. I prefer natural fertilizer; "fish emulsion" will do nicely at - or slightly less than - recommended dilution. A few pieces of charcoal (like that used in fish tank filters - but NOT bar-b-cue briquettes which contain flammable solvents) mixed into the soil helps. An ounce or two for a gallon-size pot should do. Just as effective are the small, partially-burned and blackened wood chunks from the fireplace or wood stove.

Plants should be re-potted in fresh soil once per year, removing and replacing any loose soil which can be gently shaken from the root mass.

Insects are rare, probably because essential herbal oils in the foliage are powerfully pungent.

One final suggestion...they're not too fond of very cold night-time temperatures. It's best not to allow the plants to fall below 50-degrees (F) overnight. Same holds true for most normally-outdoor plants kept indoors over winter. Heavy drapes drawn between plants and window...or a piece of insulation-board ("blue-board" is lightweight, effective and convenient) set in position just after sundown works well to offer protection from chill and drafts.

That's about the total story of Rosemary grown indoors. It can be tricky business...but certainly not outside the capabilities of thoughtful gardeners... and assuming the "rules" are adhered to.

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