Making Seed Compost
If you're having trouble starting plants by seed, it might not be the seeds that are the problem but the mix you planted them in. Experimenting with ingredients and proportions allows you to provide the mixture that best meets your plants' needs.
With just three ingredients, Dan Hinkley, of Heronswood Nursery in Kingston, Washington, makes an all-purpose seed compost for even the fussiest perennials and shrubs, including firethorn (Pyracantha) and Pernettya (sometimes known as Gaultheria). He uses sand and perlite to improve drainage and aeration; peat to improve the mixture's ability to retain air and water by increasing the amount of pore space; and, in small amounts, superphosphate and dolomitic lime, which act as nutrients and pH balancers.
1 part coarse sand
1 part perlite
1 part peat
1 tablespoon superphosphate
1 tablespoon dolomitic lime
1. Measure and add all the ingredients to the bucket.
2. Lightly moisten the materials before mixing them to help hold down the dust and bind the ingredients together -- but don't soak the mixture or you'll make a muddy mess.
3. To protect yourself from airborne dust, wear a mask. Carefully toss the ingredients to ensure that pockets of materials are not left unincorporated.