Royal Horticultural Society.


Award of Garden Merit.  This is given by the RHS to species which have performed outstandingly well in their trials.


This refers to a variety that has been recommended by the National Institute of Agricultural Botany.


There are several seed varieties which have F1 after the name of the plant.  This refers to the fact that the plant is a hybrid produced by crossing two carefully selected parents of the same species that have been developed through a process of self-fertilisation or “inbreeding” over a number of generations.  F1 varieties are normally both more uniform and vigorous than normal open-pollinated varieties.  Seeds saved from these plants will not replicate the uniformity of the first sowing.  Due to the more complex breeding involved, F1 seeds are more expensive.


When an F1 hybrid self-fertilises or is crossed with another F1 hybrid, the result is referred to as an F2.  F2 varieties retain some, though by no means all, of the vigour and uniformity of the F1 parent(s). These hybrids often have other desirable features and are generally cheaper than the F1.


An annual is a plant that completes its full lifecycle, from germination, through flowering and seed production to death within one growing season.  This type of plant can only be grown from seed.


A biennial is a plant that completes its full lifecycle in two years, flowering and dying in its second season.


A perennial plant is capable of living for a minimum of three seasons.  All herbaceous plants, trees, shrubs and bulbs are perennials.


Hardy plants can tolerate outdoor conditions at all times of the year without the need for protection.


These types of plants will tolerate ordinary garden conditions in the warmer months but are not able to survive frosts.


Tender plants cannot tolerate cold conditions.  They originate from tropical or sub-tropical areas and like warmth at all times and will not survive if the temperatures drop below 5ºc.  As a result, they are only suited to indoor cultivation except in the warmest summer months.