Q: Is it too early to spray dandelions? They are beginning to bloom, and so far I am just picking off the flowers.
A: I control dandelions by doing what you are doing—removing the source of seeds for future plants. I know of no better way to get rid of dandelions. It is true that they are perennials, surviving winter by storing food in a taproot. However, dandelions are short-lived perennials. Each plant lives only a few years; new plants grow from seed, just as annual flowers do. Every time a flower is picked, the source of new plants shrinks.
I have been picking dandelion flowers for many years, and I do not expect ever to see the last one. There are too many dandelions in the neighborhood whose seeds never are picked. They will blow onto my lawn on the prevailing winds, and a few of them will germinate and grow into new plants.
If a single dandelion blooms in a wide area of lawn (yes, that really does happen after several years of picking flowers), I may not permit its leaves to grow, either. I cut the plant below the crown. If it was large and healthy, it may grow a new top one more time. Without leaves to feed it, the root soon starves. I never bother digging out the root; that would be a large amount of work for a small benefit.
I do not know a good reason for spraying dandelions with herbicide. If they grow so thickly that there is no room for grass, perhaps so. But if you choose to spray dandelions, remember that you will have no effect on seed production. By the time that herbicide kills a dandelion plant—after two weeks—the plant has made flower buds, opened flowers, ripened seeds, and dispersed them on the wind. To get rid of dandelions it is necessary to remove the flowers from sprayed plants as well as unsprayed.
Since dandelions ripen seeds quickly, I collect open flowers as I pick them; I do not leave them on the grass. Unopened buds I drop; they will wither before they produce ripe seeds. This is a point on which I experimented to be sure. An unopened bud may open where it lies on the grass. It may even produce its miniature parachutes. But the parachutes carry only an empty stem; no seed had time to develop.
Even with a big lawn, I have few dandelions to pick every spring, and less than a dozen which produce late summer flowers with the second flush of bloom. I suppose that I could decide that dandelions have attractive flowers and deserve to be among the broad-leaved plants which I allow in the lawn. Somehow, I do not think that I will ever manage to feel that way.
The name “dandelion” comes from the French dent-de-lion, which means lion’s teeth. Of course, it refers to the leaf shape. Probably dandelions arrived in this country on the Mayflower, brought here deliberately because they were used as medicinal plants. Although many of their uses have been superseded by other sources, there is still one widely practiced medicinal use. Next time you have a sting or an itchy insect bite, try rubbing it with the sap from a dandelion stem.
Another virtue of dandelions is that they are an excellent early food for bees, before many other flowers are available.
Young dandelion leaves are good in salads, never bitter as long as they are picked before the plant makes flowers. The leaves are high in vitamins. They contain more beta carotene than carrots, and more potassium than broccoli or spinach, plus some iron and copper. That does not mean that I find them an attractive lawn.
Q: When should I prune my forsythia? It has not bloomed well for the last two years.
A: A maxim of old English gardeners—and they have 700 years’ experience—is that the time to prune is when you have time to do the job.
The gardening manuals say that forsythia, lilacs, and other shrubs which bloom in spring should be pruned immediately after they flower. That may be ideal, but the difference is not great. Forsythia can be pruned in late winter, as is recommended for summer-blooming shrubs. The only reason for avoiding winter pruning is that some pruned branches might include flower buds, which of course would be pruned off with the branch.
The flower buds on forsythia form during the summer, live invisibly on the branches all winter, and open in the spring. Shrubs which bloom later in the year do not form flower buds until spring. When those shrubs are pruned in late winter, no flower buds are cut off because they have not yet formed.
Cutting off forsythia branches with buds is no big deal. Many people do so quite deliberately, cutting branches in February and arranging them in a vase so that they will bloom indoors. Obviously, the time when you pruned did not cause sparse flowering.
The responsibility for lack of bloom rests on Montana winter weather. After a mild winter, all the local forsythia burst into bloom. If there has been any time of sudden cold, or a prolonged spell of below zero nights, or cold weather without insulating snow, the forsythia buds can die. They can die before they are big enough to notice their existence. They can die with just one night of killing temperatures. This year’s buds probably died during last October’s cold snap.
I grew up in northern Ohio, where forsythia bloomed dependably, so dependably that the proliferation of yellow bushes every spring was uninteresting. The flowering of forsythia here is chancy. Unfortunately, the bushes do not have much to recommend them for the rest of the year. That is why I choose not to grow forsythia; other shrubs will flower dependably every year because they bloom later or because their flower buds will tolerate more cold.
Q: What is the highest temperature recommended for a greenhouse?
A: Aim to have a maximum of 90 degrees. With this cool spring, temperatures which are too high may seem laughable, but they will come. Many plants do not pollinate well when temperatures are above 90. A friend from Georgia was telling me just the other day how much easier it is to garden in Montana, where summers are not endlessly hot and humid. Summer ventilation of a greenhouse is crucial to success.
THE BIG PICTURE
Everyone is talking about the responsibility of gardeners these days. It seems that whatever one grows, however one cares for plants, someone will criticize it. Here is a simple answer from gardening guru Monty Don: “Garden as you would be done by. The planet is not a remote concept but is right here. The Earth is your back garden. So do the right thing. Everybody wins.”