Romneya coulteri (California Tree Poppy) seeds
Winner of the RHS Award of Garden Merit
Hardy Shrub (to -5C)
Flowers: Late summer to early autumn
Height: up to 2m
Position: Full sun
Packet of 30 seeds
These seeds have a double dormancy which needs to be broken before they will germinate, ie. they need to go through a process which simulates the changing seasons.
Pre-sowing Treatment: Wash the seeds briefly with white spirit, then rinse with warm water.
Sowing Instructions: Sow at any time of year, very thinly in pots of an equal mix of sand & peat-based seed compost eg. Levington. Sow on the surface and do not cover seed as light is beneficial to germination and seal inside a polythene bag. Maintain an optimum temperature of 16-20C for 20 weeks, then place the container(s) in the fridge for a further 30 weeks. Then, return to 16-20C and germination should take place. Throughout this process check regularly and ensure the compost does not dry out. Note: Germination can be very erratic, so sow thinly and prick out the seedlings as they become large enough to handle disturbing the rest of the compost as little as possible.
Alternatively, sow as above, and place in a cold frame or sheltered part of the garden and let nature take its course as the seasons change. I would recommend this method for greater success and much less hassle!
Growing Instructions: Transplant seedlings when large enough to handle into 7.5cm pots taking great care not to damage the roots. Grow on at the same temperature for 3-4 months until well-rooted, then move to a coldframe for over-wintering. Plant out the following spring in a sheltered sunny site, 1.2-2m apart.