Tweaking temperature gets indoor orchids to re-flower

GardeningOctober 17, 2012 

It must be winter. Emails are piling up. Time to answer a few here.

Let's start with orchids. Everyone loves them, but most are afraid of trying to grow them because they are so exotic-looking. It turns out that most are extremely easy to grow and induce to re-flower. The main trick to get re-flowering is to keep them in a place where the temperature drops 10 degrees at night. In the old days in Japan, people would move orchids up into the cooler hills at night and bring them down during the day. It must have been nice to be the Emperor.

Mere mortals can get the same impact by keeping or moving plants closer to a window at night. Or keep them in a room where you can adjust the thermostat to automatically drop at night. Of course, it does help to have some supplemental lights during the day, but you already have those, right?

Next, sprouts. A reader says hers get "rotty and slimy" and become inedible. The trick here is to change the water daily while growing. Another good idea is to let water used to grow sprouts sit for a few hours to let the chlorine off-gas. Too much chlorine is not good for plants.

How about testing soil? Is it too late? The answer is no if the soil has not become frozen. In fact, it is a great idea to test now. This way you can start fixing things early in the season before you plant. Ah, you say, your soil is frozen. Not down a few inches. Dig. One of the best labs is at www.kinseyag.com/SoilAnal.htm

How do you keep tomatoes going in the winter? This shouldn't be any trouble as they are perennials. Again, lights will help with flowering. You will need to be the pollinator. If your plants are leggy, then pinch them back. I was once told your plants need 27 leaves before they will produce flowers.

How do you know which plants will branch when pinched back? Plants with leaves arranged symmetrically, opposite each other rather than alternating up the stem will branch. Most of these plants have somewhat square stems.

Two groups of readers are concerned about whiteflies. First, those that had them in outdoor greenhouses. These folks do not need to worry. White flies need live plants. Two weeks of frozen weather in an outdoor greenhouse gets them all. Don't worry about eggs next spring as there won't be any.

As for those with white flies indoors, they are difficult to get rid of. There are biological controls, small wasps, but these only keep white flies in check. Some survive to feed the young wasps. Still, in check is better than increasing geometrically. AzaMax will work, but you will need several applications over a two-week period. Keep at it with this Neem-based product. Spray at night when they are all on the infested plants. And, naturally, it helps to toss these plants if you can handle the loss.

Poinsettias can sometimes be forced to produce flowers and their colorful bracts. Start ensuring your plant receives less than 10 hours of light. Darkness must be total. If necessary, put a box over yours every night. Even the light from a street lamp can ruin the process, so be careful.

Finally, should you fertilize houseplants in the winter? That depends. Does your plant know it is winter? If you use lights, as you should, then you probably need to feed your plants. I use the same organic stuff used outdoors. And, I mulch my house plants. If you have not used chemicals, one or two applications all winter should suffice.

Reach Jeff Lowenfels, co-author of "Teaming With Microbes: The Organic Gardener's Guide To The Soil Food Web," at www.teamingwithmicrobes.com/home or 10 a.m. to noon on Saturdays on KBYR 700 AM or www.kbyr.com.

Garden calendar HOUSEPLANT WATERING: TRY WATERING FROM THE BOTTOM BY PUTTING PLANTS ON SAUCERS AND FILLING UP ONCE A WEEK OR SO. LIGHTS: WHAT ARE YOU WAITING FOR? INSTALL SOME FOR YOUR PLANTS. Garden calendar HOUSEPLANT WATERING: TRY WATERING FROM THE BOTTOM BY PUTTING PLANTS ON SAUCERS AND FILLING UP ONCE A WEEK OR SO. LIGHTS: WHAT ARE YOU WAITING FOR? INSTALL SOME FOR YOUR PLANTS.

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