F 1 hybrid seed is expensive as it has to be recreated by crossing the parent inbred lines again. Self pollination of the parent inbred lines leads to poor quality plants called ‘selfs’. Preventing selfs is complicated and costly which also contributes to the expense of F 1 hybrid seed Greater uniformity of flowering, stature, yield and maturity period.Although uniformity is usually more valuable to commercial growers, hybrids usually offer worthwhile advantages to home gardenersover other forms of seeds When a group of selected plants are grown together and allowed to freely pollinate each other, the seed is said to be open-pollinated. Before the advent of hybrids all seeds were open-pollinated. Open-pollinated seeds are the only option for plants that cannot be easily inbred – lettuces, peas and runner beans for example.

Theses are plants produced by crossing different species, for example Viburnum farreri and V. grandiflorum. The resulting offspring are indicated by an × symbol before the species name. This can occur in the wild but more are common in cultivation, as in Viburnum × bodnantense. Greater size and vigour of flowers or produce due to the phenomenon of hybrid vigour (heterosis). Hybrids are therefore more robust and better able to overcome adverse growing conditions Perhaps surprisingly then, when two inbred lines are crossed, the first generation (F 1) is uniform and vigorous due to heterosis. Hybrid vigour is not fully understood but crosses between certain lines will produce especially vigorous offspring. Breeders of F 1 hybrids aim to use parent lines whose progeny show particularly strong hybrid vigour. Open-pollinated seed is available for all crops offered as hybrids, but is usually significantly less uniform, vigorous and productive. Open-pollinated seed is relatively inexpensive and can often be readily collected by home gardeners. However, seeds harvested from garden plants will not always come true to their parent, particularly if there is a related plant nearby with which it could have hybridised. Other hybrids usually sold as plants rather than seed: