Here is a blog about the biennial technique. This technique can be used by landscapers in Ireland. If you are a landscaping gardener then this will be of use to you.
Uses: Hardy Biennials which can be transplanted into beds in autumn. Hardy perennials which can be transplanted into pots in Autumn. Nearly all named varieties of perennials fail to breed true from seed. But you might not mind having a mixure of colours. The real problem landscapers might have is that you might to wait some time before perennials reach flowering size.
- Prepare nursery bed – this is a special plot of ground set aside for raising seedlings. Follow the rules for preparing the soil for hardy annuals.
- Prepare seed drills – follow the rules for preparing drills for hardy annuals. The drills should be 1 foot apart and labelled with the name of the varieties grown.
- Irish garden designers should, as soon as the seedlings reach a good level,be thinned to about 2 inches apart.
- Plant out in autumn when the plants are 1 1/5 – 2 Inches high. Lift up each plant with a trowel and transfer it with its soil ball to the bed or border where it is to flower.