You often hear me talking about deep-root watering and feeding trees. It's all about putting a series of holes in the soil around a tree's drip line. All the details are in this tip sheet.
On last weekend's GardenLine radio programs, I noted that all the recent rains have provided an opportune time to try this as a do-it-yourself project. After four days of downpours, the ground may never be easier auger into. Besides, you don’t have to get your holes down 14-18 inches. In fact, recent research suggests 8-10 inches will do the job because most of the fibrous roots that do the absorbing are in that zone. Still, getting down as deep as possible on the majority of hardwood trees is never a bad thing.
Now, really big trees — like, for example, a 25-year-old oak — might 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 (below) or a Corona Root Irrigator (top).
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. We are about a month away from what I consider the official tree pruning season, so whether you're using an auger bit for a drill, a post-hole digger for bigger trees, or just a Ross Root Feeder, there's no time like the present.
By the way, the Ross Root Feeder is a tool that should be used solely for making holes. Ignore the feeding instructions that come with it, and definitely don't use the "fertilizer" they provide. A Ross Root Feeder hooked to a hose produces a concentrated jet of water, and that is helpful in getting in some deep holes developed. But that's it.
I don't care what food you use as long as it's organic. This isn't my attempt to save the planet by getting you to go organic - it's simply the smartest food choice, not just for the tree root system, but for the soil itself, which will get supercharged with microbes and trace minerals.
One final thought and a warning about scam-like offers from some supposed arborists who may try to talk you out of deep-root feeding your trees. You’ll know them when they instead recommend some injections into the tree’s cambium layer to supposedly feed it. Such services can cost $1,000 or more per tree, and they won’t guarantee it will save a sickly tree. If they could, I’d pay that kind of money. But they don’t offer a guarantee - they know they can’t. I know of one “arborist” who left the state when their over-priced scam was exposed.
Reputable tree companies, who have been at this for years, will always promote deep-root feeding as 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, here’s a story from not long ago about removing tree roots. This subject came up at the tail end of last weekend’s show, so it’s worth a read for those who see a lot of big tree roots emerging. You can’t make ‘em go down, but a deep-root feeding and about an inch of enriched topsoil per year to start covering them up will help. And remember … you should only remove one big root per year.
PHOTOS: Corona, Randy Lemmon