Loving the colorful splash of seasonal foliage kicking off, signaling the much-needed slowdown for plants needing a rest before next Spring.
I especially adore the brilliant native non-allergenic sumacs and even the reds and yellows of its notorious cousin, poison ivy vine, licking up tree trunks. A surprisingly nice show is bald cypress with its complex brownish mélange of rust, bronze, and dull gold.
But brown is not always good thing. The most sinister example in too many gardens this time of year, including my own, is when normally-green landscape shrubs suddenly “brown out” and die.
It’s nothing new. Decades ago, while studying landscape plants at MSU, I learned that some very popular plants are highly susceptible, almost predictably, to browning out because they aren’t well-adapted to our climate or were planted poorly to begin with.
Sometimes, it is because they are native to cooler climates and have a hard time coping with both our torrid summers with all-night heat and humidity, and fickle winters with ups and downs that confuse botanical clocks. They may take it for years, even decades, but sooner or later enough of them start to peter out that it causes horticulturists to reluctantly recommending their landscape uses.
The plants I have consistently diagnosed doing this over the decades include popular boxwoods, Japanese hollies, Leyland cypress and various other exotic conifers (arborvitae, blue spruce, Hinoki false cypress), Japanese maples, azaleas, blueberries, Loropetalum, and Japanese yew. All very widely-planted landscape choices, all susceptible to weather-related problems.
It’s been bad lately; I’ve lost yaupon hollies, unkillable nandinas, and a Little Gem magnolia! It’s heart-breaking when it happens just as they mature into important accents.
Though it often seems to happen suddenly, most of the time it is a slow process as roots develop soil-borne diseases, an unseen stress that leads to dead or dying limbs. This is most common when roots are damaged from staying too wet part of the year, which may not be an issue unless another blow like a hot, dry spell comes along and the leaves are unable to get all the moisture they need.
But the problem is often caused indirectly from plants being set into heavy clay soil, or up against a building where soil is compacted, especially if they are planted too hurriedly in the first place. When shoved into small holes with slick sides, the new roots are unable to shoot out into the surrounding soil.
Also, if new trees, shrubs, or even flowers and vegetable transplants don’t have their potting soil loosened and stirred into the native dirt, the stunted root balls stay wetter and later dry out more quickly than the surrounding soil. And as old potting soil decomposes it usually leaves roots suspended in just a root-filled cavity in the ground.
The bottom line when a shrub or tree browns out in mid-summer or fall, it probably has had ongoing problems with a poor, constricted root system and has been subjected to back-to-back long wet and dry spells. And if just one or two shrubs in a row are looking bad, it’s a good bet that those are just the weakest, and all the others are having the same problems.
This has been happening a lot lately, even to trees in the woods. What to do? Choose good plants to begin with. Dig wide holes and don’t over-amend the soil. Loosen roots when planting. Water at least once a month but no more than once a week. If a shrub or tree has dead branches, prune them out as best you can and hope for the best.
Felder Rushing is a Mississippi author, columnist, and host of the “Gestalt Gardener” on MPB Think Radio. Email gardening questions to rushingfelder@yahoo.com.
