When should I prune my
overgrown forsythia in my garden?
Along the Front Range,
we generally enjoyed a good early spring for forsythia bloom due to many of the
newer clones such as ‘Meadowlark’, ‘New Hampshire Gold’, ‘Sunrise’, and
‘Northern Sun’, which have better flower bud hardiness and are being sold and planted more.
One should prune forsythia after flowering by thinning one third of the older
canes by cutting them to ground. It is important to remove the oldest branches
and weak and dead wood. This will encourage new growth and more flower buds
which are formed in late summer to fall for next spring.
If the shrubs are
overgrown, you may want to rejuvenate your shrub in February by trimming the
entire plant to 3 to 6 inches above the ground.
No matter which of
these two pruning techniques you choose, your overgrown shrub will bloom
heavier and will be more showy in future years. You will lose bloom color if
you choose rejuvenation pruning but will
gain it back in future years.
[photo by David Staats] Forsythia in full bloom at the CSU Arboretum |
My irises are done
blooming and is this the time to divide?
Clumps of bearded
irises should be divided and replanted before they become overcrowded. A single rhizome will
branch many times over the years, developing into heavy criss-cross clump,
often choked with old leafless rhizomes. If it is not divided, the mass of
leaves will exclude sun and air from roots. This will lead to poor flowering or
no flowering and often weakens the plants making them more susceptible to
insects and disease.
Photo by David Staats |
Dividing of irises is
best done after bloom (late June into July) which is the same time that
plantings should be made. Lift each clump by gently prying it loose from the
soil. A spading fork is better for this than a shovel because it is less likely
to cut roots and rhizomes.
Use a sharp, strong
bladed knife to trim younger rhizomes into sections that include healthy
looking roots and one or two strong leaf fans. Carefully wash soil off roots
under low pressure from a hose. Discard old rhizomes from center sections.
Trim existing leaves to
a neat fan shape and then dig a hole to replant so that the rhizome will be set
no deeper than one inch. Check to be sure that all leaf fans face the same way
and spread roots out evenly. Firm the soil around the rhizome to eliminate
major air pockets in the soil.
Photo by David Staats |
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