Species clematis seed will produce
offspring that are virtually indistinguishable
from the mother plant. However, seed of hybrid
clematis or any of the large-flowered cultivars
will produce plants which vary from similar to,
to very different from, the mother plant. Sow ripened
seed as soon as you obtain it. The time of germination
will vary, but will not be improved by delaying
the sowing. Species clematis and many small-flowered
types can germinate in six weeks, but can take
a year or more if conditions are not to their liking.
The seed of large-flowered clematis may remain
dormant for up to three years, so have patience!
Sowing the seed
Containers can be 7.5cm to 10cm
square or round pots (3-4"), or half size seed
trays. Many clematis make long initial roots, so
the deeper the containers, the easier the transplanting.
John Innes (or other good quality)
soil-based seed compost is satisfactory but it
must be free draining, so mix in extra grit.
Fill the pot to within about 1.25cm
(half an inch) of the top with pre-wetted and drained
seed compost-grit mixture, gently firm, and sow
the seed evenly on the surface. Feathery, persistent
styles on some types of seed can be cut off to
make spacing easier. Allow 1cm or more (1/2" or
so) spacing - the more the better.
Sieve just enough of the same compost
on top to cover the seeds then add very coarse
sand or grit on top to a depth of 5mm (1/4"). This
will prevent liverwort and protect against disturbance.
Stand the completed pot or tray in water containing
a fungicide, and remove when the grit on top shows
signs of dampness. Label clearly with the name
of the seed and the date of planting. Place the
pots or trays in a cold greenhouse so that they
are well-lit but never in direct sunlight. Whilst
the seeds are germinating, keep the compost moist
but not saturated.
The first signs of growth are usually
weeds and these should be removed very carefully. Let
the seedlings reach 5cm (2") or so before transplanting
- late summer is a good time to do this. If they are
not big enough, leave the seedlings until the following
spring. Tall seedlings can be pinched back as required
at each stage of repotting. Use 6cm (2.5") pots or
larger for the initial potting on. Stand the pots in
a sheltered pot in the garden, or in a cold greenhouse
- either way, out of direct sunlight. Don't forget
to label each pot carefully.
Adapted and abridged from BCS
Factsheet No.4 'Notes on propagation of clematis
from seed and softwood cuttings' by Mike Brown
and the late Vince Denny