Gardening From Alaska

...growing plants indoors
by Jeff Lowenfels
by Jeff Lowenfels


Jeff is the Past President of the Garden Writers of America, a columnist with the Anchorage Daily News, Host Alaska Gardens and Supporter of Plant a Row.

November 9, 2003

I won’t beat around the bush. There is really no way around lights if you want to grow plants indoors during the winter months in Alaska. Sure some plants will limp along and others like our outdoor pelargoniums, amaryllises, epiphyllums and cactuses might even thrive.

Still, who wants plants that merely limp along? The idea is to have healthy, vibrant plants in your home. And, in addition to healthy plants and plants that flower, lights allow you to grow vegetables, as well as other things, that we can’t grow in our cool, summer climate.

Your set up doesn’t have to get any more complicated than using a simple two or four bulb shop fixture with 40 watt, cool white, fluorescent bulbs with some kind of system that allows the height of the lights to be adjusted. Add to this a simple timer so you don’t have to turn the lights on and off and you are set. Total cost? Under 25 dollars.

Fluorescent systems don’t put out much heat which makes them idea for starting seeds and cuttings. They can be put within an inch of the soil or foliage. Plants will do best if they are kept within 6 to 12 inches of the lights.

If you want to improve on this simple system, which always means more money, you can get bulbs with what is known as a higher “Kelvin temperature.” Most florescent bulbs have a Kelvin temperature number on them or salespeople should be able to look that number up for you. You want to get bulbs in the range of 5,000 Kelvin output. Check with any of the Hydroponics supply stores, electrical stores and even the lighting departments of large box stores.

Next up the line is HID lighting or high intensity discharge lights. There are three or four different kinds and it is pretty easy to get mixed up. All you need to know is that for the money and efficiency, you can’t go or grow wrong using High Pressure Sodium (HPS) lamps. The bulbs cost about 20 dollars, which is affordable, and last two years or so. Fixtures for these continue to drop in price. Again, any of the hydroponics suppliers in town as well as electrical hardware stores will carry these bulbs and the necessary fixtures.

HPS lamps come in 250 watt, 360 watt, 400 watt and 1000-watt sizes. A 250-watt bulb, hung at six feet, will light an area about 20 square feet or an area the size of a card table. A 360 watt bulb at the same height will light an area 35 square feet while a 400 watt bulb will cover 40 square feet. If you want a bulb that you can hang higher, a 1000 watt bulb hung at 9 feet will light a 120 square feet area.

HPS lamps do require special ballasts that are usually located away from the bulb fixture. Each is rated for one wattage only and you should never mix bulbs with the wrong ballasts.

A close runner up for convenience and efficiency are metal halide (MH) lamp systems. However you have to be extremely careful when hanging metal halide lights. If they are angled at more than 15 degrees, they throw off dangerous UV rays. A 1000-watt system hung at 9 feet will light about 100 square feet while a 400-watt hung at 6 feet system will light 40 square feet. All in all, the HPS is a better deal and obviously safer.

Whatever you settle on, you will need a timer as well.

Any light system should be set so the lights are on between 13 and 15 hours most of the time. Shorten this to 11 hours if you are growing annuals that you want to force into flower. If you have more than one light set up you might consider having a short day area and a long day area.

There are all sorts of things to grow under lights. You can start almost anything from seed and it is always fun to try and grow some of those left over from this spring. What else are you going to do with them? Cactuses, begonias and other houseplants are also fun to grow from seed as are a whole host of herbs, lettuces, pepper and tomatoes. And, your choice of things to start next spring will be greater if you can start things under lights.

You don’t have to keep all your plants under these lights all the time, though it wouldn’t hurt them a bit if you did. However, when you have plants that are not doing well, both you and your indoor plants will be glad you put up lights.

Jeff’s Alaska Garden Calendar for the Week

Christmas and Thanksgiving cactuses: Set buds now. Withhold water and place in a cool room with natural day light. Water once buds form.

Driveways and paths: Mark yours now to keep traffic and snow plows off the lawn this winter.

Birdfeeders: It is still a bit too early. Bears are still roaming. One or two more weeks should do it. Clean yours, however. Buy seed now, but store indoors.


  • New Eden
  • Kids Garden
  • Plant a Row Grow a Row