COLLECTING SEEDS

Collect alder seeds by gathering ripe cones in autumn. When dried the cones will open and can be shaken, in a bag or tin box, to help release the seeds.
Separate seeds from the cones using a riddle or a large sieve.

STORAGE/TREATMENT OF SEEDS

Store the seed in a cool dry place in a natural fibre (hessian is best choice) bag. Never store fresh seed in a plastic bag because it excludes air and causes the seed to heat up thereby lessening its viability.
They should be stratified for one month prior to sowing, in a mixture of sand and peat substitute. Stratification is a cool damp storage period which allows the seed to prepare for germination.

SOWING SEEDS

Seeds may be sown in the spring, either in seed beds for larger scale production or on a smaller scale in seed trays. For a large seedbed, broadcast the seed onto the soil. Roll the seed bed to fix the seed to the bed. It is crucial for the seed to have proper contact with the soil. Lightly cover with coarse sand using a riddle. Ensure that the seed bed does not dry out during germination.
On a smaller scale sow by sprinkling thinly onto well moistened general purpose seed compost in seed trays or pots. Do not cover the seeds with soil. If you want, you can cover the seed trays with glass to prevent the seed bed drying out. Leave it outdoors in the shade (make sure it is not in direct sunlight). Again, ensure the seed tray never dries out.
When the seeds have germinated the seedlings can be treated as you would any vegetable or flower seed.
Pick out the seedlings, holding them by the two coytledons (the first green leaves which develop from the seed). The seedlings may be planted into pots, plug trays, or prepared open ground.
Young trees can then be planted out after one year's growth, but it is usually safer to wait for two years.