GARDENING : Checking Your Methods Is Far From Madness

Whenever you try something new in gardening, it makes sense to devise ways to determine whether it made a difference. Otherwise, you can never be sure that it is worth repeating.

For example, if you plan to try different pansies, grow some of last season’s types alongside the new ones. That will provide a side-by-side reference.

Or in applying a mulch, leave some plants without any. Did those that weren’t mulched need watering more often? Did the mulch attract damaging insects? Did it improve the appearance of the garden?

Or, if considering a new fertilizer, use the regular type on half the plants and the new one on the others. Then judge the results.

Researchers use double-blind tests on such projects. Gardeners need nothing that elaborate. If you feel the new approach was better, you can safely adopt it for your conditions.

But this does require observation. And unless there is some check, there is no way to be sure.

Otherwise, it could just mean that the season was particularly good and everything would have performed as well anyway.

And don’t be influenced by the “we-have-always-done-it-that-way” factor.

As an example, take the recommended way to dig holes for new plants. For generations, the method of choice was a hole about twice the diameter and depth of the root ball and the blending of at least 33% soil amendments, such as peat moss, into the backfill.

But the University of Arizona’s Jimmy L. Tipton says “new research clearly shows traditional techniques aren’t best for new plants.” He says they work against the desirable, quick establishment of a wide, lateral root system that supports a plant and absorbs water and nutrients.

What’s better, he believes, is no amended backfill and a planting hole no deeper than the root ball but three to five times its diameter. He feels that roots will not extend easily beyond a highly amended backfill and, besides that, most native soil has a higher water-holding capacity, promoting growth.

Zinc sulfate has been touted as a way to control thrips on roses by applying a cup under the bush before the bloom period. Try it on half of your roses and see if it makes a difference.

In much of the West, many professionals believe gypsum (calcium sulfate) will help cure many soil problems, much as lime does in the East. One common test of gypsum’s effectiveness is to use a stick to mark a 5-by-5-foot piece of ground.

Gypsum is sprinkled on one half and nothing on the other half. Both halves are watered normally. After the soil dries, gypsum advocates say you will see that the gypsum-covered soil will be puffier and looser looking.

But where sodium in soil or water is not a problem, this won’t work.

Epsom salts provide another example. Many rose growers swear by the effectiveness of this soluble form of magnesium sulfate. Plants do need trace amounts and magnesium is a little bit stronger than sodium in clinging to soil, so it can replace the sodium.

Yet many experts consider gypsum and Epsom salts worthless.

So it seems to depend on local conditions. Which brings us back to square one: Make your own tests and keep records.