Plants may be sold as ‘bare’, ‘balled’ or ‘ grown’. Bare root means that they are lifted from a nursery bed and that all, or most, of the soil adhering to the is shaken off so that the plants are as light as possible to transport. Transplanting bare root can be done only in autumn and winter when plants are dormant or nearly so. It is the cheapest way of buying plants, but many kinds, particularly evergreens, cannot be transplanted safely in this way, even at the most favourable periods.
Balled plants are also lifted from nursery beds but with as much soil as practicable and this soil is then held around thewith hessian or polythene so that it does not fall off during transplantation. Balled plants weigh a great deal more than bare root plants and so cost more to transport, but provided the work of balling and replanting is well done they have a better chance of survival. The planting season is a little more extended, balled evergreens often being moved in early spring or early autumn.
Container-grown plants are those that are really well established in, polythene bags or anything else which will ensure that all the roots and the soil around them can be transported and planted with the minimum of disturbance. Well-grown container plants can be put in at any time of the year when the soil is in good working condition, but they weigh more and usually cost more than comparable bare root or balled plants. Most of the shrubs and climbers offered for sale in garden centres are container grown and this is an ideal method for the cash and carry trade. Even for mail order many are pot grown since some do not transplant well in any other way, and it is a method used for many other plants that resent root breakage, such as brooms, romneya and perowskia.
Some plants refuse to grow in alkaline soils unless regularly fed with iron and manganese in specially prepared (chelated or sequestrated) forms.and azaleas are two of the most important of plants in this category and unless one is prepared to make special acid soil beds for them it is really unwise to attempt to grow them on soils containing much chalk or limestone. Other lime-hating plants are mentioned in the individual notes on plants.