Why Don’t We Just Fertilize When Plants Look Sick?

The first picture shows Rhododendrons that have been in the ground about five years. They look yellow and a good candidate for fertilization.

The second picture shows the roots from one of the plants in this group that died. You can still see the shape of the pot that the plant came in from the nursery. These plants have never sent roots out to the surrounding soil and fertilizer would be a waste of time and money. These roots should have been cut and spread out at planting. Some of these plants may still be saved by using a sharp shovel to cut the roots at a few places radially to the plant. In a year after this treatment fertilizer will probably then be a benefit.

Sometimes even trees that are not planted too deep or mulched to death develop root problems. It is always worth a check if other causes of decline can not be determined. One clue that a tree may have root problems is that other trees next to them look fine.

This tree is not doing well. The pictures that follow show that this tree has cross roots (roots that grow over other roots) these were cutting into the main roots of the tree. See the big gouges in these roots after I cut off the offending roots. Unfortunately this is not an exact science, some cross roots were left until the tree recovers and will be removed at a later date.



Not the best Photo but I think you can still see the large root that I left for another time.

This next tree is about ten feet from a driveway and at the bottom of a slope. For some reason, probably run off over the years one side of this tree was about nine inches too deep. This usually causes girdling roots (the roots you can see circling and gouging into the trunk). Unfortunately by the time I thought to take photos I had already cut off some of the worst offenders. I think you can see the gouges and some of these offending roots.


(With apologies to the memory of Sir Walter Scott)
Oh what a tangled web we weave
when first we practice burying trees.

The sister tree to this sick looking maple is dead. Look how deep it was. This tree had no chance of survival. What a waste of money and trees. The last picture in this series shows a tree planted correctly. Note you can see the butt swell and the top of the first major root.

The following trees are examples of typical landscape trees being volcano mulched to death.
I guarantee that most of the trees in this parking lot will be dead within ten years and probably much faster. So someone paid to have these trees killed.


If any one ever reads this blog they are probably thinking boy this guy is a nag about his roots and stuff. Probably true but it really irks me to see people wasting money and killing plants.

The root work on these trees was done by exposing the roots with a tool called an air spade which blasts air at high pressure to remove the soil. You can use a hose to take a look if you are curios about a tree you have. A hose will make a huge muddy mess if you want to do more then just take a surface look. Forget trying the rake and shovel unless you like grueling heavy work. The air spade also will not damage roots like a shovel and rake. If you are feeling adventurous here is how I built my air spade.

If you do find root problems, roots can be removed with a chisel. Try to make clean cuts and do as little damage to other roots as possible. As I mentioned before there is no scientific amount of roots that you can remove and be sure not to kill the tree. If in doubt and you want to try this yourself you can do one side of the tree one season then the other side the next season.
If you do it this way do the worst side first.

As for the time of year to do root work, I am told that it does not make a difference. Obviously you can’t do it after the ground is frozen. I do not think it prudent to do this between the leaf drop and leaf out of the deciduous trees. It being my thought that why cut off roots that the tree has spent energy on to fill with food.

After serious root pruning keep the tree watered, but not waterlogged for a while. At this point a light application of root stimulator fertilizer can benefit the tree. Root stimulator fertilizer means no, or very low nitrogen, you do not want to encourage top growth that the roots can’t keep up with. I prefer just compost, you can’t go wrong with compost and it has anti-fungal, anti-viral and anti-bacterial qualities that can’t hurt.

Now a short bit about weather. Both drought and too much rain can reduce the root mass of a plant. The worst situation is drought broken by a lot of rain the next year. The effects of drought can affect a tree for several years following as the roots take time to grow back.

Improper fertilization
of trees sick from drought, too much water, diseases, insects, root and other problems can do more harm then good.

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