Q. My lilacs have bloomed
and the flowers are gone. Is now the time to prune or do nothing? How do you prune
or care for the lilacs.
 |
| Lilac planted in rock mulch with brown scorched leaves |
 |
| Shrub pruned with heading cuts close to the ground |
A. Most people don't know
that low-chill varieties of common lilac will grow here as well as the Persian
lilacs. Plant them in plenty of sunlight but in places which avoid the hot
afternoon sun. All lilacs must be planted in a composted soil with a wood chip
mulch. Rock mulch will not work.
Low-chill
varieties do not need as much low temperatures to produce flowers. Lilacs that
are not low chill will not produce as many flowers in our warm winter climate. Some
plants require long periods of time when temperatures are cold so that flowers
will be produced the next year.
Persian
lilac may be a better choice for our climate and in smaller yards than common
lilac. Persian lilacs are smaller in stature than common lilac, with smaller
flower clusters and a lower winter chill requirement.
Hopefully
local nurseries and garden centers that sell lilacs for our climate are
selecting low-chill types such as an old time favorite here called "Lavender
Lady". I believe this, along with "Angel White" were the first
low chill lilacs available that would grow in the desert Southwest. Many of
these low-chill varieties are referred to as the “Descanso Hybrids”.
Lilacs
are not desert plants so they require lots of compost mixed in the soil at the
time of planting with the soil covered in wood chips that decay over time. They
should not be in rock mulch.
A very nice article appeared
in Sunset Magazine and you can read it here
http://www.sunset.com/garden/flowers-plants/mild-climate-lilacs
As
with any seasonal flowering shrub or tree the best time to prune them is soon
after flowering. If pruned later than this, the flowers for next year may not
be produced.
First,
remove the dead flowers before they form seeds by cutting them off at the base.
Next, if needed, cut back branches or stems.
To
increase the number of flowers you should increase the number of new branches
it produces. Use a "heading cut". This type of cut is made somewhere
along the length of the branch, usually just above a leaf on the outside of the
branch.
Heading
cuts grow three or four new shoots for every one that is cut that is made. This
is an excellent way to make a shrub denser with more flowers.
If the shrub is getting
too large, remove one third of all the longest stems back to within a couple of
inches above ground. New stems will grow from just below these cuts.
A
radical way of pruning this plant is to totally cut it off just above the soil
surface. With plenty of water and some fertilizer new shoots will grow from
these very short stubs resulting in an all-new plant. This is pretty radical
but if the plant is overgrown with lots of wood showing, this may be your only
alternative.
Remember,
after pruning give it plenty of water and fertilize it with an all-purpose
fertilizer.
