The factors affecting hardiness are not well understood, either individually or in combination and certainly involve a great deal more than low temperature. For this purpose, we have assigned a rating to each plant based on experience and observation over many years and indicating practical terms, the sort of climatic conditions in which the plant could normally be expected to succeed.
Hardiness 1: The ‘Fragile Few’
Suitable only for the mildest areas of the country (e.g. Southern Counties, sheltered coastal areas further north) and local favourable microclimates. Often spectacular in flower and useful for this in the right location. Unfortunately too tender for general planting and for this reason, we offer few varieties of this hardiness.
Hardiness 2: The ‘Townies’
Given a reasonable degree of shelter from the north and east, these plants are perfectly happy in all but the coolest inland areas. Much used in the urban landscape where the microclimate usually offers protection. Unsuitable for exposed sites.
Hardiness 3: The ‘Infantry’
The tougher ornamentals. This group comprises a broad palette of plants suitable for mass planting anywhere in the UK. The footsoldiers of urban landscape design but usually inappropriate for the rural environment.
Hardiness 4: The ‘Gladiators’
The real ‘toughies’. Will withstand anything the British climate can throw at them except perhaps physical damage from gales.