As I sat down to write for you today I was thinking of some things a lot of us take for granted. I realized there are a lot of odd little facts that pop up in gardening that may not make sense to newcomers. Some you will know. Others you may not. Let’s see how it goes.
▪ Woody plants must be transplanted while they’re dormant, and that means during the winter (soon!). By “transplanting,” I’m talking about digging them and relocating them with subsequent loss of roots in the process. This is not to be confused with simple planting, where you go to the nursery, buy the plants, bring them home and set them out. That can be done at any time.
▪ Ninety percent of any tree’s roots are in the top foot of soil. It doesn’t matter if the tree is growing in the alluvial soils of a flooding river bottom or atop a whiterock escarpment, the majority of its roots will be where the rainfall hits — near the soil surface. The concept of “taproots” gets overplayed vastly.
▪ The average date of the last killing freeze in the Metroplex is somewhere around March 18 or 20, but it’s a bell-shaped curve. A couple of weeks ahead of that time you still have a 90 percent chance of a freeze or killing frost. A couple of weeks after that time you still have a 10 percent chance. Plant accordingly.
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▪ Vegetable crops have very precise planting time windows. Each type of vegetable has its own preferred temperatures for germinating, growing and maturing. Know the recommended planting date of each for your area, and follow them closely. Plant too early and your crops will be killed or will stall. Plant too late and they’ll be ruined by heat.
▪ You can girdle and kill a tree with a wire or trimmer. As a tree’s trunk grows in girth, it will swell through any wire left in place around it (like the fellow whose belt is too tight). Eventually the cambium layer will be severed and no more phloem (layer that carries sugars from the leaves down to the roots) will be produced, so the plant will die. Gouging through the bark with a trimmer or dog chain will do the same thing, just many times faster.
▪ There is no grass that will grow in heavy shade. This will probably be the subject of an entire column later this spring, but for now just take my word for it. If you have heavy shade, and if pruning is not an option, then it’s time to start choosing shade-tolerant ground covers. “Miracle” cures or grasses that promise you can have a lawn in heavy shade are bogus.
▪ Phosphorus (middle number of the fertilizer analysis) is slowly soluble, and repeated applications of fertilizer containing it will result in harmful build-ups of phosphorus levels in heavy clay soils. That’s why Texas A&M soil scientists have been encouraging us for years to use high-quality, nitrogen-only fertilizers with half or more of that nitrogen in slow-release form.
▪ You dig and divide flowering perennials in the season opposite of their bloom time. That means that spring-blooming perennials like violets, iris and Shasta daises are divided in the fall (October), while fall-flowering perennials like mums, fall asters and Mexican bush salvia are divided in very late winter/very early spring (February). Summer-flowering types like cannas and hardy hibiscus can be moved at either time.
▪ No tree or shrub is truly evergreen. All plants exchange old leaves for new. Live oaks are doing so now. Hollies and ligustrums will start changing in late March and April. Pines and junipers drop needles all through the growing season. Magnolias have their big leaf drop in late April and May. It’s all very predictable, and it’s all very normal.
▪ It’s better to water deeply less often than it is to water lightly and frequently. That’s why the guy at the end of a garden hose squirting his lawn is doing the turfgrass a big disservice. By watering deeply and then letting the soil dry somewhat before you water again, you are encouraging your turfgrass and landscape plants to produce deeper roots, making them better able to survive times between irrigations.
▪ “Apical dominance” means that the bud closest to the growing tip of a branch gets the plant hormones and will have the most active new growth. You can direct a shrub’s growth by where you make each cut as you trim. Prune just above a bud that faces away from the center of the plant and you’ll encourage outward growth. Prune above a bud facing in toward the center and you’ll end up with congested growth as the tip shoots develop.
▪ “Native” refers to where a plant is found growing in nature. But that can vary from one mile to the next. You can’t assume that plants from one spot will grow with great fervor 50 miles down the road. It’s fine to grow native Texas plants whenever you can, but always ask if they’re also “adapted.”