100 PruninG Perennials
TO SEED OR NOT TO SEED
The question of whether you should deadhead to prevent self-seeding depends
primarily on your objectives for the garden and how you want to spend your
time: deadheading or removing seedlings. The weather can influence deadhead-
ing needs because it affects the amount of reseeding that occurs; wet springs, for
example, can greatly enhance germination. Another consideration is whether
the seeds will develop into the desirable plant. Species forms will grow true to
type from seed, but cultivars may not and so allowing them to go to seed can be a
pitfall. Sometimes this provides the gardener with pleasant surprises, but
usually they are not so pleasant—these unpleasant progeny can take over the
desirable cultivar, leaving you wondering what you started with. This is often the
case with Phlox paniculata.
Personally, I like some seeding in my gardens to promote that “unplanned”
look. This approach can be promoted a bit too much, and I pay the price by
spending a great deal of time removing unwanted plants. On the other hand,
perennials such as columbine and rose campion (Silene coronaria) are rather
short-lived and readily perpetuate themselves if allowed to self-sow. Biennials
such as sweet William (Dianthus barbatus), as well as some of my favorite annuals
like nigella or love-in-a-mist (Nigella damascena), I treat as perennials because
they self-sow reliably. The nigella plants stay close by the feet of their original
parents. A point that also comes into play when deciding whether to allow plants
to seed is whether the seeds fall close to the parent (which won’t mean too much
work) or scatter everywhere (which can result in a great deal of work). You can be
selective with your deadheading, particularly with prolific seeders, and remove
all but a few deadheads to allow smaller numbers of seedlings in. This is a good
approach but takes some forethought. If seeding is desired but the deadhead is
unattractive, as in the case of a spiked flower like digitalis, the spike can be
shortened, thus still allowing for some seeding but without being so obtrusive.Seedling variability
in Phlox paniculata.
(opposite) The
spontaneous purple and blue
provided by seeding of alpine
columbine (Aquilegia alpina)
and Hungarian speedwell
(Veronica austriaca subsp.
teucrium) add greatly to this
cottage garden.