Growing from seed

Introduction

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, or half-sized 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 of the top with pre-wetted and drained seed compost and grit mixture, gently firm down 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 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. 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.

Potting on

The first signs of growth are usually weeds and these should be removed very carefully. Let the seedlings reach 5cm 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 pots or larger for the initial potting on. Stand the pots in a sheltered spot in the garden, or in a cold greenhouse – either way, out of direct sunlight. Don't forget to label each pot carefully.