I often talk about deep-root watering and feeding trees. It's all about putting small holes in the soil around a tree's drip line, then scattering organic fertilizer about so it percolates down through them. All the details are in this tip sheet.
Thanks to all the rain we’ve received over the past two weeks, there may never be a better time to do this on your own, because the ground may never be easier to auger into. And recent research suggests you no longer need to get down 14-18 inches into the soil. Just 8-10 inches will do, because most of the fibrous roots that do the absorbing are in that zone. Still, getting down as deep as possible with the majority of hardwood trees is never a bad thing.
Now, really big trees — like, for example, a 25-year-old oak — might still be difficult to handle on your own. You should probably leave something like that to a commercial tree company. Professional equipment can be far more efficient than a Ross Root Feeder, a one-inch auger drill bit, or a Corona Root Irrigator.
I'm often asked what the average price might be for a professional deep-root feeding. That always depends on how big the tree is, but you can find rates as low as $75 each for trees younger than 10 years. Costs can climb to as high as $200 per tree if the canopy is very wide. You may be able to negotiate lower unit costs when having multiple trees done at the same time. Sometimes, professional tree companies will throw in a free deep-root feeding for any mature tree they prune. But be careful with that deal right now, because the normal pruning season is November through March.
By the way, the Ross Root Feeder should be used solely for making holes. Ignore the feeding instructions that come with it, and definitely don't use the fertilizer they provide. This tool is hooked up to a hose to produce a concentrated water jet, which is helpful in developing deep holes. But that's it.
I don't care what fertilizer you use as long as it's organic. This isn't my attempt to save the planet - it's simply the smartest food choice for the tree root system and the soil itself, which will get supercharged with microbes and trace minerals.
And here’s a warning about scam offers from some “arborists” who may try to talk you out of a deep-root feeding and, instead, let them inject some “food” into the tree’s cambium. Such services can cost $1,000 or more per tree, and there’s no guarantee it will save a sickly tree. If it could do that for sure, I’d pay that kind of money. But they don’t offer a guarantee because they can’t. I know of one “arborist” who left the state when their overpriced scam was exposed. Reputable tree companies, who have been at this for years, will always promote deep-root feeding as a benefit for just about every tree, and for a fraction of the cost.
And while we are on the subject of tree care and roots, read my article about removing tree roots. This subject came up at the tail end of last weekend’s show, so it’s worth a read if you have a lot of big tree roots emerging. You can’t make ‘em go down, but a deep-root feeding and covering them up with about an inch of enriched topsoil each year will eventually help. And if you're thinking about removing any roots, never take out more than a single big one annually.
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