Making a Cytisus (Broom) hedge

[Jenster]

I plan on making a small ornamental border hedge with Cytisus (Boskoop Ruby or similar). Border is about 2m in length, in full sun and exposed to wind.

Can anyone recommend planting density, i.e. how many plants per meter length? And the best age of plants to use.

Any other tips or advice on this idea.

Thanks.