Q: Is it true that I can avoid insecticides by growing herbs? Will herbs repel insect pests?
A: Horticulturists have no easy answer to that question. Experiments in a laboratory show that the aroma (and flavor) of various herbs do have an effect on insects. The aroma molecules either attract or repel bugs. When the lab experiments were moved outdoors, though, the results were only confusing.
It is certain that most herbs, when they are in bloom, do a splendid job of attracting beneficial insects. Bringing in the good bugs may be more important than repelling bad ones.
Beneficial insects help the garden by pollinating plants. They also help by eating pest insects. It does not take too many years of gardening to know that there is no better way to solve the bad bug problem than to have beneficial insects take on the job. Natural pest elimination always beats insecticides hands down.
It is not at all clear how pest insects choose their plants for dinner. Studies have shown that the pests landed on any green area. They did not even prefer real to artificial plants. The only place that insects avoided was bare earth. Only after they landed did the insects seem to decide whether to stay. If it was not a plant that the pests normally ate, they soon flew away. If it was part of their usual diet, they stayed.
This all suggests that whether your plants are eaten may be partly a matter of luck. There certainly are no final answers, but it may be that herbs in the garden are really good at serving as a distraction. They may attract some insect pests, thus keeping them away from the plants they intended to eat. In that way herbs would be excellent pest protection.
We are not likely to see experiments that will clarify the answers to the question of herbs for pest control, since this kind of experiment is costly. Someone with deep pockets to underwrite the cost of an experiment will appear on the scene only if the experimental results will pay off. Who would make money by proving that herbs do or do not repel insects?
Q: I need a gardening project for January, besides looking at seed lists. Is there anything I can do outdoors that isn’t complicated by frozen ground?
A: How about spending some time on a fresh look at your garden and yard — this time from the inside looking out? For all the gardening season we look at plants from where we are gardening, or we consider the view from the street, the front path, the driveway.
However, for about half the year we see our landscape as we look out through a window. Surely that view is as important as the one seen from outside.
At this time of year, shapes matter more than bright colors. Are there leafless trees or tree branches that are particularly beautiful? If so, how can they become a focal point in the view from a window? Are there flowers or grasses which should be left standing until spring because of their shape? Are there broken stems to remove now? Is there an empty spot that is crying out for some garden ornament to catch the eye? When you look at all the views backwards, you may see a whole new world out there.
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Q: I do not want my gardening to add plastic to the waste stream, but how can I possibly accomplish that? All my potting soil comes in plastic bags, all the plants are in plastic pots, all the labels are plastic.
A: I have the same concern. Any move away from plastic in gardening will be a slow one. But if every gardener makes just one change, the results will add up. What change could you make? You could buy wooden stakes instead of plastic ones, or you could make your own stakes by cutting strips from used plastic food containers. You could reuse your existing plastic pots until they break. You could deliver used plastic pots to your favorite nursery for recycling. You could plant seeds in paper pots instead of plastic ones. I do that, and I get healthier seedlings by doing so.
It is always unsettling and sometimes annoying to have the botanical taxonomists announce that they are reclassifying a plant and changing its name. Unfortunately, we need to prepare ourselves for ever more of this sort of change. For a few hundred years, scientists have been grouping plants by the way they look: what shape are the leaves? do they grow in pairs? how many petals are on a flower?
The groups get divided by much finer details, of course, but they all depend on what can be seen — sometimes with a magnifying glass. Now botanists have the ability to identify plant DNA. So far this has meant that a few plants turn out to be more closely related to each other than would be obvious by looking at them. Botanists are changing names to reflect this.
The DNA studies show that rosemary is really another kind of sage. Botanically its name will change from Rosmarinus officinalis to Salvia rosmarinus. No labels will change immediately because nurseries are not going to throw away their old labels. They will buy new labels only when the old ones are gone. But do not worry if you see plants that look like rosemary but are labeled as “rosemary sage.” They will be the same rosemary that you have been buying for years.
Why bother to change the names at all? Sometimes if plants are closely related, they will all serve as hosts of the same pest or disease. If an insect started eating your pineapple sage, for instance, you would be forewarned to watch out for it on your rosemary, since you now know that they are closely related.
Another name change resulting from DNA studies is that African violets will now be classified as a kind of Cape primrose. Will growers start calling rosemary “sage” and African violet “Cape primrose”? Or will botanists and gardeners begin to speak different languages? Or will there be further name changes? Only time will tell. Perhaps younger and older generations of gardeners will call plants by different names. Whatever any of us calls them, the plants themselves will remain the same.
If you are trying to sprout an avocado seed and nothing seems to be happening, don’t give up hope. I planted two seeds a couple of months ago, telling myself that I would throw them away if nothing was happening by New Year’s Day. Nothing was visible, but when I probed with my finger in the soil, sure enough! A root was snaking its way out of a crack in the bottom of each seed. There will be avocado trees to come.