By Robin Y Rivet.
October is prime tree planting season in San Diego County. The weather is cooling and our rainy season is due. If you are expecting to plant a containerized sapling from a nursery, you MUST inspect the root system. There generally won’t be a tap-root, but you’re very likely to find kinked or circling roots. Although modern tree planting guidelines tell you to “check for girdling roots”, they typically are light on explanations about how to accomplish this, and most planting instructions simply avoid the topic entirely. YOU SHOULD NOT. Instead, you might consider washing the potting soil off of all your nursery acquisitions – with clean root pruners in hand.
By the way, you can ignore this essay if you’ve collected acorns or eucalyptus seeds, and are ambitious to germinate them, or you plan to peruse winter catalogs and plant bare-root specimens in early spring. Or maybe you’ve noticed volunteer seedlings sprouting up around your neighborhood? With care, you can uproot and re-plant these as is. Self-sown juveniles often have a lengthy tap-root that you should gently dig up intact, preferably during a cool morning or evening. Unlike tree containers, these are all fabulous options to rear the healthiest and longest-lived trees.
Alternatively, here’s some shopping and grooming tips:
· Buy small:
Liners, or one-gallon containers - or less. The smallest specimens are not guaranteed to be free of rootbound problems, but the roots may be supple enough to stretch out appropriately.
· Buy medium:
With prudent attention, you can buy five-gallon specimens or smaller - like #2’s or #3’s. These may need some root-washing and light to moderate root clipping, but they usually survive the ordeal, and are the better for it - even if they go through a period of sulking.
· If you purchase a 15 gallon or larger pot: Be prepared to wash the roots thoroughly and perform major, or at least minor tree root surgery. Although the risk of doom is real, blindly planting and praying is worse.
· My suggestion is to avoid boxed specimens:
Most are difficult to inspect, and are often severely rootbound. Many are too defective to correct at this size.
If you do not pay attention now:
· Your tree may seem fine for the first 5-10 years.
· As circling roots swell, they begin to girdle each other, and can eventually strangle the main trunk as they reach upward and coil.
· Cramped root crowns may also cause infrastructure conflicts above ground, as they aren’t spreading as they should, but rather swirl and swell in place, outgrowing the soil space.
· Unchecked underground, kinked roots make it increasingly difficult to extract water from compacted urban soils, transport sugars for root health, or even stabilize a tree during a storm.
· Without food and water, trees eventually die slow deaths.
Learn more about trimming & washing tree roots, and best practice planting techniques: https://www.slideshare.net/LindaCS/bare-root-primer https://s3.wp.wsu.edu/uploads/sites/403/2015/03/fragile-roots.pdf https://s3.wp.wsu.edu/uploads/sites/403/2015/03/Planting-fact-sheet.pdf https://www.fire.ca.gov/media/5018/nurserytreeproductionstrategies_10_2009-1.pdf
Member Robin Rivet is an ISA Certified Arborist – contact her: treetutor@gmail.com
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