This may seem a fairly simple subject to most of you who have already planted trees successfully. Whatever methods you employed obviously worked so why change? Trees are very resilient creatures and as such will do their darnedest to live in spite of whatever misguided or well intentioned care we give them. Would it interest you to know that topsoil, staking, tree spikes, peat moss, root stimulators, plus a whole bunch of other accoutrements sold to aid us with tree establishment aren’t really necessary? Some in fact are detrimental. Read on and I’ll give you my take on the latest techniques and technology.
THE PURCHASE- Buy container grown or containerized trees. Bare root or balled and burlap trees are just about extinct in today‘s market. With the exception of mail-order nurseries you don’t find anyone offering bare root anymore. There are some nursery professionals who still will argue that a good balled and burlap tree will eventually form a better root system since container grown trees do by nature tend to have wrapped or girdled roots. However the bottom line still is livability. Even a perfectly dug ball and burlap tree will have most of (say 70% or more) the vital feeder roots cut off. Container grown trees will at least have all roots intact even if they are a bit cramped or wrapped around in the pot. Containerized trees are those that have been dug and placed in containers. These are held for a season to allow the tree to heal and grow new feeder roots. Buying trees has always been about the roots. Without ample roots the tree with the best looking top just isn’t going to make it. The top of the tree does matter for sure, but not as much as most people think. Bear in mind that you can cut the top completely off most sapling trees and they will almost immediately start to grow a new one. It is better to buy a small tree in a big pot than a big tree in a small pot. Don’t spend so much time looking at the top and look at the bottom. You are buying roots.
THE HOLE- Today we recommend that tree holes should be wide rather than deep. The depth should be no deeper than the depth of the soil in the container you buy. We now say we want the top of the root mass even with or slightly higher than the surrounding grade level. This is in direct contrast to “the old days” when we were told to plant the tree below grade. The width of the hole should be a minimum or 1 1/2 times the diameter of the root mass. Wider is better. Most folks are really interested in fast growth on a newly planted tree. The best way to achieve this is by providing loosened soil for the feeder roots to travel in to. The deeper roots or “tap root” functions in part as an anchor so we want the tighter subsoil available to it. Make certain the bottom of the hole is flat as your nursery container is also flat on the bottom. Digging a hole down to a pointed shape can result in an air pocket trapped beneath that can kill the tree.
SOIL AMENDMENTS- In the past, a person would be sent home with all sorts of soil amendments to go with the tree purchase. After extensive university research the best results actually came from backfilling the hole with the native soil that was dug out. During these tests all sorts of different soil amendments were used including the popular fertilizers, top soils, peat moss, etc. Still, the “control” tree eventually caught and surpassed the other trees as time went by. From this we learned that trees established much quicker by getting them acclimated to the native soil as soon as we can. All other methods showed only short term gains at best. “Underground pots” are now considered a thing of the past.
The latest technology involves soil microbes. It has been known for a long time that all plants including trees have symbiotic relationships with beneficial microbes. We now sell dormant mycorrhizal fungi and different rhizobacteria to make certain that these microbes are present in sufficient number when the tree is planted. So we no longer sell root stimulators but we do sell microbes which, by the way, one application of will colonize, increase, and stay with the tree for the lifetime of the tree. The only other soil amendment you should need besides the microbes is compost.
Backfill the hole with native soil. Do not compact the soil. Settle the backfill gently with water. In the top 4” to 6” of the backfill you should introduce your beneficial fungi and bacteria with compost mixed into the native soil. Top off with an additional 1” of pure compost then mulch with a biodegradable product such as tree leaves or bark mulch. Do not pile these items up on the trunk. Spread them away so that the root flare is exposed.
STAKING- This is one of the old methods that was actually found to give negative results. Staking does restrict the vascular system in the same way that a stretch bandage on your wrist will reduce blood flow to your hand. Now matter how soft or stretchy the material is you are still binding the trunk. Evidence of this can easily be seen when the material is removed. It always leaves a visible mark. In addition it was found that the tree will make use of this extra support and it often act as a crutch to support top growth. If you have made the mistake of buying a top heavy tree it is better to cut the top back to the point where the trunk can easily support the weight. As the tree grows back it will strengthen itself accordingly. Although we humans still feel the need to support a young sapling, the facts are that the action of wind, water, ice, and snow are exactly what is needed to encourage strong trunks and deep rooting.
AFTERCARE- You will want to water your new tree several times during the first week or so to settle the soil. After that comes the hard part. How much is too much or not enough? This is where most people fail.
Unlike grass, trees respond best to deep but infrequent watering. A 15 minute cycle from an automatic sprinkler once or twice a week may be just fine for your grass. Remember that trees are deep rooted creatures. When in doubt, check your moisture level by digging down around the edge of your planting hole. If moisture is present near the surface, then leave the tree alone. Different soils percolate and dry out at different intervals so it is best to know how well your particular soil holds moisture. Dig a hole and fill it repeatedly with water to find out. Also the temperature, humidity, and wind speed play a big part. Add that to the fact that soil that has been composted and mulched will hold water much better than bare soil. From this you can easily see that there really is no stock one-size-fits-all solution or schedule. What we tell people is one deep watering per week in the absence of adequate (1/2” inch or more) rainfall and to wait at least a week after a good rain before watering again. Watering is best accomplished with drip irrigation or a trickle from the water hose.
Trees take a long time to get established to the point of being able to exist on normal rainfall. If you have chosen the right kind of tree for your location this should happen somewhere between three to five years after planting. The thing to look for is vigorous top growth. During establishment the new tree will send more energy to root development and the top will be seen to grow slowly. Finally one spring you will notice the tree will take off like a rocket. This will signal you that the roots are becoming established. At this stage you will want to begin to wean your tree off of extra irrigation. Begin to withhold irrigation except for long dry periods (which may happen at any time, including winter) and during heat waves. After a season or two of this you may stop extra watering completely.
All this talk of watering may sound pretty involved but it really isn’t if you will get away from trying to schedule and just use some common sense. Most trees do not need constant moisture. Most novices tend to over water. Just water deeply, when you do, irrigate, then back off, and pay attention to the weather. Buy a rain gauge; you’ll get the hang of it. Allow the tree to fend for itself as time goes by and realize that trees are the longest living, most resilient living things on this planet. You and I can make mistakes; the tree will suffer but often as not survive.
Stick with trees that are natives and trees that are known survivors in your area. Always look around town for mature specimens of trees you would like to try. If you don’t find many or any at all then there is probably a very good reason for it. Don’t think you are the first one to fall in love with a “sweetheart” or a fad tree. Be wary of any advertisement that makes outlandish claims regarding growth rate or other performance. Right now is the proper time to plant. Unlike many of the investments we make in life, trees should last well beyond our life span and continue to serve those who are yet to come. Leave something good for the next generation………Plant a tree!!