<P> Nurseries may supply plants for gardens, for agriculture, for forestry and for conservation biology . </P> <P> Some of them specialize in one phase of the process: propagation, growing out, or retail sale; or in one type of plant: e.g., groundcovers, shade plants, or rock garden plants . Some produce bulk stock, whether seedlings or grafted, of particular varieties for purposes such as fruit trees for orchards, or timber trees for forestry . Some produce stock seasonally, ready in springtime for export to colder regions where propagation could not have been started so early, or to regions where seasonal pests prevent profitable growing early in the season . </P> <P> Nurseries can grow plants in open fields, on container fields, in tunnels or greenhouses . In open fields, nurseries grow ornamental trees, shrubs and herbaceous perennials, especially the plants meant for the wholesale trade or for amenity plantings . On a containerfield nurseries grow small trees, shrubs and herbaceous plants, usually destined for sales in garden centers . Nurseries also grow plants in greenhouses, a building of glass or in plastic tunnels, designed to protect young plants from harsh weather (especially frost. While allowing access to light and ventilation, modern greenhouses allow automated control of temperature, ventilation and light and semi-automated watering and feeding . Some also have fold - back roofs to allow "hardening - off" of plants without the need for manual transfer to outdoor beds . </P> <P> Most nurseries remain high standard . Although some processes have been mechanised and automated, while others haven't . remains highly unlikely that all plants treated in the same way at the same time will arrive at the same condition together, so plant care requires observation, judgment and manual dexterity; selection for sale requires comparison and judgment . A UK nurseryman has estimated (in 2003) that manpower accounts for 70% of his production costs . The largest UK nurseries have moved to minimize labour costs by the use of computer controlled warehousing methods: plants are pallet allocated to a location and grown on there with little human intervention . Picking merely requires selection of a batch and manual quality control before dispatch . In other cases, a high loss rate during maturation is accepted for the reduction in detailed plant maintenance costs . </P>

Describe the preparation of a nursery bed for raising flowers