Ailanthus altissima (Tree of Heaven) seeds
Height: 20m if not pruned
Position: Sun or semi-shade and deep, fertile, well-drained soil
Pre-sowing Treatment: Soak the seeds in water that starts off hand hot for 24 hours.
Sowing Instructions: Sow * at any time of the year. Mix equal parts of loam-based seed compost, eg. John Innes with vermiculite, perlite or horticultural grit and sow seeds very thinly on the surface, then just cover them with a layer of vermiculite, perlite or grit. Seal inside a polythene bag and place in the fridge for 4 weeks. After this, move to a propagator or other warm place and maintain an optimum temperature of 12-17C. Germination should take place in 1-3 months. 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.
An alternative method is to sow in pots as above during late summer to early winter then place in a cold frame and let nature take its course as the seasons change with the seedlings emerging the next spring.
Growing Instructions: Transplant seedlings when large enough to handle into 7.5cm pots. Over-winter in a frost free place for the first winter, then off and plant out in spring in a sunny or semi-shaded position in deep, fertile, well-drained soil.
* Seeds may come mixed with lots of debris – sow the whole lot together.