Q: What is eating little holes in my potato leaves?
Q: My tomato leaves have little holes in them. What should I do?
Q: My radish leaves have little holes, but I don't see any bugs eating on them. What is going on?
A: Small holes in early summer, in the leaves of any vegetable, are the hallmark of flea beetles. These beetles are about the size of fleas and they hop like fleas, so they usually remain invisible to gardeners. Fortunately, their appetites match their physical size. Flea beetle holes are tiny. As leaves grow the holes in them also enlarge, but even by midsummer they will never be bigger than a quarter of an inch.
What should be done about flea beetles? Nothing. Their damage is minimal. The only time that flea beetles can eat a plant to death is when it is a seedling with tiny leaves, just emerging from the ground. Miniature seedlings may need to be grown under mesh until they are bigger than a flea beetle's appetite. Otherwise, gardeners can consider the holes just a cosmetic blemish.
Q: When I try to grow herbs from seed, usually I start them in small pots, in the house. They always begin growing just fine, but then something goes wrong. Some years it seems that half the herb plants have died off before they have been thinned enough to plant in the garden. Sometimes they live that long but die soon after transplanting. How can I grow healthy herb plants
A: The short answer is: don't thin them too much, too quickly. Several different herbs (as well as several perennial flowers) like to be left in small groups, their seedlings set out as a clump. With vegetables that would not be a good idea. Carrots or corn left in a clump would make crowded and dwarfed plants. Not so with many herbs.
Some herbs, including thyme and parsley, prefer to thin themselves. If a seedling clump seems too dense, cut off half the seedlings with scissors, but always leave four to six plants to figure out the survival of the fittest. Sometimes they will all survive and be fit.
Second, do not begin the thinning process too soon. Let plants grow their seed leaves and then four true leaves before removing any weaklings. Most herbs begin life in slow motion, and weeks may have passed before it is time to start thinning. The strongest and healthiest plants may not be visible immediately. They may not be the first seeds to germinate nor the fastest to gain height. When thinning, do so gradually. First remove the obvious failures; a week or two later, thin to a reasonable number.
Third, never, never thin by pulling out unwanted plants. Pulling may injure or kill all the remaining ones. Seedling roots are fragile, and some are very fragile. Thin only by cutting off unwanted plants, even if it means a trip back to the house to get a forgotten pair of scissors.
Q: If hollyhocks get rust and I cut off the infected leaves, is it all right to put them in the compost?
A: No. The compost would become a breeding ground for hollyhock rust. Any leaves which exhibit rust symptoms should be destroyed. I do not even cut off infected hollyhock leaves. If any leaves show tiny yellow, orange, or brown spots, I dig the whole plant immediately, so that I do not spread rust to other hollyhocks.
In past years I have stopped growing hollyhocks for about three years when rust appeared. When I tried again, with fresh seed, the rust was gone. But hollyhocks are so susceptible to rust that a new disease outbreak may appear after several years without rust.
Because each rust disease attacks only one kind of plant, the hollyhock rust can never travel to a rose, for example. Nor can a rose rust jump to a hollyhock. All rusts are what botanists refer to as "species specific."
Master gardener Molly Hackett, whose motto is “Never trust a gardener with clean fingernails,” welcomes your questions. Send them to 1384 Meridian Road, Victor, MT 59875; call 961-4614; or email email@example.com. Please include a garden-related subject line in emails. Hackett writes a twice-monthly Dirty Fingernails opinion piece for the Missoulian.