When to plant lilies
Ideally plant in early autumn, although bulbs can be planted until spring.
Lilies can also be forced into flower for an indoor display. The bulbs will have been kept in a cool environment in order to flower without natural winter chill being necessary. Forcing involves bringing the pot into the warmth of the house or heated greenhouse, for flowering around six weeks after planting.
Planting lilies in containers
Preparing the container
Place a 5cm (2in) layer of drainage material, such as crocks or small stones, in the base of clay pots before beginning to fill with potting compost. Plastic containers may not need this ‘crocking’ if their drainage holes are raised off the bottom of the container.
Plant single large bulbs (10-12cm (4-5in) diameter) into 20-23cm (8-9in) diameter containers, or plant three to four smaller bulbs (5-8cm (2-3in) diameter) into 23-25cm (9-10in) diameter containers. Allow 5cm (2in) between bulbs and use only deep containers.
Some lilies, such as the Asiatic hybrids, root from the base of the bulb only. Others, including L. formosanum, L. lancifolium
and L. longiflorum
, produce roots not just from the base of the bulb but also from the stem just above the bulb – these lilies may need a deeper container.
Plant basal-rooting lilies (or those whose habit is unknown) at a depth equal to the height of the bulb. Plant stem-rooting lilies at a depth roughly two-and-a-half times the height of the bulb.
The bulbs should be planted with their basal plate (which has hair-like roots hanging down from it) facing downwards, and the pointed tip of the bulb scales pointing upwards.
Although any good multipurpose compost is suitable, soil-based John Innes composts are easier to manage in terms of watering and feeding. John Innes No 3 is recommended for most lilies. If it appears too dense, add 20 per cent by volume each of horticultural grit and ericaceous soil-less compost or leaf mould.
Some lilies are lime-haters (e.g. L. auratum
and L. speciosum
), and should be potted into pure ericaceous compost. John Innes ericaceous compost is recommended.
Lilies are heavy feeders, so add granules of a controlled-release fertiliser when planting.
Ensure the compost is moist at all times, but not wet. Feed with a high potassium liquid fertiliser such as tomato feed every fortnight during summer.
To speed up flowering (i.e. force the bulbs) move plants to conditions of 18-21ºC (64-68ºF) when shoots appear.
Re-pot in autumn when the foliage dies down, or transfer bulbs to the garden. In larger containers, lilies can be grown on for a second season in the same pot, but ensure that the top 5cm (2in) of compost is replaced with fresh compost with some added fertiliser or well rotted manure.
Ideally keep containers in a cool but frost-free, airy place with strong light, such as a well-ventilated cold greenhouse or frame.
In southern England many lilies will be fully hardy and can be left outside in larger container year round. It may, however, be necessary to wrap the containers in winter with bubble polythene in cold areas to protect against frost. In very cold areas, or where tender lilies are grown, keep containers in frost-free sheds until spring.
To guard against waterlogging, stand containers in the rain shadow of a wall or keep in an unheated greenhouse or in a shed.
Lilies usually need cool winter conditions if they are to flower well, so indoor conditions are not suitable over winter.
(Source: The Royal Horticultural Society 2014)