Hardening, aphids & quackgrass

Q: What on earth does it mean to "harden" a plant?

A: It is gardeners' slang for helping an indoor plant to adapt itself to outdoor weather. The same techniques are used for plants grown in a greenhouse or bought at a nursery.

The leaf surfaces of plants are delicate if they have always been warm, have never felt wind, have never seen bright sun. Amazingly, plants can toughen their leaves to adjust to weather, but they cannot do so instantly. It is as if the plant grows itself a jacket, and the process takes about a week.

If a house or greenhouse plant is put outdoors, it probably will survive. However, it will have a great shock, stop growing, recover itself and finally start growing again. Leaves may turn red; that is sunburn. Leaves may die; that is like sunburned, peeling skin.

Gardeners "harden" or "harden off" plants to get them used to outdoor weather gradually. The system that I like is to set the plants outdoors during the warm part of the day, in the shade and away from any wind. The plants come back into the house for the night. I carry them out and in for three days.

For the next three days I repeat the process, except that I set the plants where they will see morning sun and afternoon shade. They still move to a place where wind will not buffet them. They still are brought indoors every night.

For another day or three, until I find time to set the plants in the garden, I put them where they get sun all day but still no wind. I bring them indoors at night if I expect temperatures do drop below 40 degrees. By that time they are hardened to outdoor conditions. If I have timed it right, frosts are over and I will not have to cover the plants on some cold night.

Q: I have thousands of aphids. I have sprayed with everything I can think of, and they keep coming back. What can I do?

A: First of all, you can worry less about aphids. Gross as they are to look at, they do serious damage only to small plants, where they can literally cover all the leaves. It is true that aphids suck plant juices, but bigger plants will survive the attack. Except for seedlings, the first thing to do about aphids is to wait for two days. A great many creatures like to eat aphids. If you can stand being patient, birds and bugs may slurp up all your aphids.

If it seems necessary to spray aphids out of existence, use plain water from a hose. Once they are knocked off a plant, they are not smart enough to crawl back where they were. Furthermore, if they were eating when the water knocked them down, their mouths will be broken. They can eat no more.

The morning after you have given aphids a shower, you will say, "Oh, no! They are all back! That didn't work!"

Not so. Those are new aphids, which are born every day. Spray them with water also. You can put various chemicals into the water, but plain water works just as well. You may have to spray aphids for several days in a row, but no aphid outbreak lasts longer than two weeks. It just seems like forever.

If you see aphids later this summer, they will be on different plants. There are several kinds of aphids, all specialists that eat only one family of plants.

Q: How can I keep quackgrass out of my vegetable beds?

A: The only way I know is to keep a grass-free border around the beds. An inch or two of mulch on surrounding paths makes it easy to pull any grass that dares to come up in the path. Tilling the paths weekly also will keep quackgrass under control.

If quackgrass plants show up in the vegetables, simply cut them at ground level. Quackgrass roots and rhizomes extend many feet deep and wide. Cut plants will not regenerate any faster than dug ones.

Hackett welcomes reader questions related to gardening, pest management, plants, soils and anything in between. Submit questions to mhackett@centric.net, call 406-961-4614 or mail questions to 1384 Meridian Road, Victor, MT 59875.