Q. We have several shrubs with an eastern exposure that
appear to be very distressed or dying. The first three photos show the entire
shrubs. Photos 4 and 5 are close ups of the distressed area. Photo 6 is a very
healthy plant in the same area but with a southern exposure. Irrigation is excellent;
enough that water is standing in the bed upon completion of the water cycle
which is five minutes and four times a week in the hot summer.
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| Japanese euonymus in question |
A. Thank you for the pictures. There are several things that might be going on
at the same time with these shrubs. They
appear to be variegated mock orange and Japanese euonymus. Many of the leaves are yellowing and
scorching or turning brown and dying from the tips back.
Most
people will look at these pictures and say they are not getting enough
water. Another person might look at the same
pictures and say they need iron. Another person may look at the same thing and
say they are getting too much water. And even another person may look at that
and say it is salt damage. The problem is they could all be correct just based
on the pictures.
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| Leaf damage closeup of Japanese euonymus |
Many of
these things, and even more, are interrelated.
Just giving more or less water or even iron may not solve the problem
alone. Let me just give you a rundown of
the problems that I see as possibilities: plants planted in the wrong spot in
the yard, improper pruning, lack of additions to the soil to improve it, wrong
type of fertilizer and improper watering.
From these
pictures, any of these could be a possibility and there could be combinations
of things going on. Let me handle each,
one at a time and perhaps you can make the best decision.
First of
all plant location. If this is a very
hot location, facing south or west with lots of reflected heat and light, then
they will not do well in this spot. This does not mean that they cannot survive
there; it just means it will require more effort to keep them looking good if
they are placed in spots that are extreme for their best health.
.jpg) |
| Variegated mock orange with scorching and dieback |
By
finding the best location for plant in a yard means that they will require less
time, energy and money to keep them looking good. A very hot location will be even more
difficult if there is no air movement and they just sit there and bake.
Pruning.
These shrubs appear to be pruned with a hedge shears into the shape of a
gumball. This type of pruning may work
for a few years but eventually this type of pruning makes the plants look ugly
and contribute to their poor health.
Pruning
with a hedge shears should be reserved for hedges, not shrubs. This type of pruning forces older wood out
closer and closer to the perimeter of the shrub. Young or juvenile wood is the only wood that
is removed.
.jpg) |
| Closeup of variegated mock orange leaf scorch |
My guess
is that you have a landscape maintenance company doing the maintenance. This is how they prune. They don’t know any
better. Very few, if any, prune shrubs properly. The
proper way is to remove ¼ to 1/3 of the shrub each time it is pruned, forcing
new growth to come from old wood deeper inside the canopy of the shrub. This rejuvenates the shrub, adds more
juvenile wood to the canopy and keeps it young and vigorous.
Soil
amendments. I could not tell from the
picture but these shrubs will perform better if they were growing in organic
mulch or wood mulch. Not bark mulch. The chipped wood decomposes into the nutrient
poor soil and adds vital nutrients for the shrubs.
Rock
mulch also breaks down but adds only minerals to the soil. The shrubs will perform better if compost is
added to the base of the plants and watered in with a hose. Compost should be added to the list of
fertilizers and soil improvements for these plants each year.
The
first year I would add about 4 cubic feet of compost per plant along with its
fertilizer applications. After two or
three years of this I would probably only add about 2 cubic feet per year. Then of course the wood mulch is an added on
top of the compost. You should start to
see improvements after one full season of growth after the additions.
Fertilizers.
The same type of fertilizer used for lawns will do a good job on most shrubs as
well. This is usually a fertilizer with
a ratio on the bag of 3-1-2 or 4-1-2. An
example of a 3-1-2 fertilizer would be something like 12-4-8 and a 4-1-2 might
be 16-4-8. You will not find these
numbers on fertilizer bags exactly but at least you can get the idea of how the
numbers should go up and down in sequence.
The next
fertilizer you need is an iron chelate such as iron EDDHA. It is expensive but can go a long way since
of the small amount is needed each year.
My apologies to other nurseries and outlets but I know that Plant World
Nursery carries this iron chelate. If
others do, let me know please. Fertilizers are added to shrubs in February of
each year.
Watering.
The frequency of watering will vary during the year but during the heat they
will probably need water about three times each week. As it gets cooler, decrease that to twice a
week, cooler yet, than once a week, etc. In the winter it should be no more
frequently than once a week.
The
gallons of water to apply is going to be difficult for you to judge because you
operate an irrigation clock in minutes. Somehow you need to get a handle on the
relationship between the minutes on your clock and the gallons delivered to the
plants.
These
plants would probably be adequately watered if they were to receive somewhere
around 5 gallons for the smaller shrubs to 10 gallons for the larger shrubs at
each irrigation.
All of
these things are interrelated and so doing just one of them may or may not be enough.
The
three top things I would investigate more closely are your watering, soil
improvement and fertilizers. If you can
get the plants healthy, then they can handle higher temperatures provided they
are pruned correctly. Hope this helps.
