Neil Sperry

Neil Sperry: Why plants behave the way they do

I’m frequently asked why one plant might be growing differently than all the seemingly identical plants surrounding it.

What started out to be a simple garden tip that I intended to post on my Facebook page turned into a much more involved answer — too much for one little tip. Oh, the symptoms vary, and the plants aren’t the same, but the nature of the issue is fairly consistent. Here … I’ll show you.

“I’ve grown lilacs and peonies in other parts of the country, but I can’t grow them in North Texas. What is the difference?”

You probably had much cooler climates in those other areas. Those are both plants that fade in the Texas heat.

That’s why it’s critical that you do your homework first, then buy from a reputable full-time nursery professional whose advice will be reliable and applicable to your locale. Gardening is like cab driving. The farther you get away from home, the less you know about what you’re doing. Everything changes.

“Why does one plant in my landscape grow so slowly, when another one of the same species right across the sidewalk thrives?”

As a parent, grandparent and human observer with more than a few years under my belt, that’s the same way it works for all living beings. Somebody catches the cold, and somebody right next to him does not. Individuals (plants or animals) just don’t always behave the same.

In the case of these two plants, they might have been from different nurseries, and they could have found their way to the landscape having faced different challenges.

Or the slower one might have gotten too dry and never recovered. It might have been root-bound at the time it was planted, with no corrective measures taken to help it become established. The vigorous one might have had better and deeper soil or better irrigation.

There could be subtle differences in the amount of lighting the two plants receive.

“Why does one oak tree have galls, while the one touching it does not?”

Genetic susceptibility has to be a key factor here. Some people are more prone to high blood pressure or baldness — or to the aforementioned cold, while a sibling is not.

Oaks grow from acorns, so the offspring will all be genetically different from the mother tree and from one another. Some varieties of crape myrtles are susceptible to powdery mildew. Others are not. Some tomatoes are bothered by nematodes. Others are not. Some live oaks put up root sprouts (not good!), while others do not.

These are just a few of the thousands of everyday genetic variations in the plants that we grow.

“Why do some of the cherry laurels in a hedgerow turn yellow, while others do not?”

If they’re growing in alkaline black clay soil such as we have over most of the Metroplex, the yellowing plants are suffering from iron deficiency. You’ll see the characteristic yellow leaves with dark green veins, most prominently displayed on the newest growth first (ends of branches).

Cherry laurels are very susceptible to iron chlorosis (as are gardenias, sweet gums and East Texas pines), and one of the plants has to begin to show problems first. It’s probably in shallow soil, perhaps with very alkaline white rock subsoil beneath it.

Leave them all in place for a few years longer and you’re likely to see the problem show up on all the plants in the row. In this case, you need to change to another type of plant entirely.

“Why does my neighbor’s garden grow and produce so much better than mine?”

One of the worst things we can do is envy the neighbors’ gardens. People tend to their plants very differently. However, the differences I see between gardeners’ practices start with soil preparation.

The best garden soils are prepared 10 to 14 inches deep. Existing vegetation is removed, then organic matter, including rich compost, pine bark mulch, well-rotted manure and sphagnum peat moss, are spread, an inch or so of each. For clay soils, an inch of expanded shale is added, and then all 5 or 6 inches of soil amendments are tilled to the full 14 inches of depth of the soil. The resulting garden will give perfect drainage, and the plants in that soil will have the best chance of thriving.

Compare that to the gardener who just spades up a few square feet, stirs in a bag of manure, and starts planting seeds of unknown variety and maybe a month after their prime time for planting.

It’s critical that you give all of your plants the best possible start to their successes, and it all begins with the soil.

Choose good varieties and quality seeds and transplants, then plant them at the proper time. Keep them moist and well nourished, and they should make you proud.

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