Advice
RHS Help & Advice
Planting lilies in pots
Most lilies are best planted in October, and bulbs are usually available from summer through to early to mid-autumn.
The pots can either be left outside in a sheltered spot in the garden, for flowering the following summer after experiencing the chilling effect of winter, or they can be ‘forced’ (Asiatic hybrids, L. auratum, L. longiflorum and L.speciosum being suitable examples).
Forcing involves bringing the pot into the warmth of the house or heated greenhouse, for flowering around six weeks after planting. Bulbs sold as suitable for forcing are usually only available in the summer, and have been kept in a cool environment in order to flower without natural winter chill being necessary.
Choosing a pot
Choose a tall pot, as many lilies have large bulbs and some need relatively deep planting. Lilies develop tall stems, and could look out of proportion in a squat pot. Your pot must have drainage holes in the bottom.
Compost
The following potting compost mix will do for most lilies:
- 3 parts John Innes No 3
- 1 part horticultural grit
- 1 part ericaceous compost or leafmould (omit this for lime-loving lilies such as L. auratum and L. speciosum; most lime haters are sold with a warning on the label, advising you of this fact; ask the seller if unsure).
Crock the pot
Fill the bottom of the pot with crocks, to ensure the bulbs have good drainage. If you don’t have enough broken bits of crockery to make a 5cm (2in) deep layer at the bottom of the pot, you can supplement with some coarse grit.
Add fertiliser
Partially fill the pot with your compost mix, adding some controlled-release fertiliser granules to provide food for the bulbs when they start to grow. If controlled-release feeds are used, then further feeding shouldn’t be necessary over the growing season. If you don’t have any controlled-release fertiliser, or if the pot used will have other plants in it too, then you can give a monthly high potassium liquid feed, such as Phostrogen or a tomato feed, over the growing season.
Planting
Different types of lilies need to be planted at different depths.
Those that root only from their basal plate can be planted like most bulbs, i.e. to a depth of twice their own length. The tip of the bulb should rest at the equivalent of one bulb’s length down in the soil.
Lilies that form additional roots at the base of their developing stems (i.e. above the bulb) need to be planted much deeper. The tips of these bulbs should rest at a depth of two-and-a-half to three times the length of the bulb. Even after such deep planting, they may need earthing-up to cover any developing root initials that appear above soil level. For this reason, stem-rooting lilies need very deep pots.
Stem-rooting lilies tend to include many of the species (as opposed to the bred cultivars). It is worth checking the label or asking the seller for details if unsure.
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.
Place the lily bulbs on the compost at the correct depth, and then cover over them with the remaining potting compost and fertiliser mix, leaving a 3cm (1in) gap at the top of the pot to allow for watering.
Label the pot so that you know which bulbs it contains. If you wish, you can cover the surface of the compost with decorative mulch such as grit or clay pebbles.
Water in the bulbs.
Lilies don’t need much water over the winter (when unforced), but shouldn’t be allowed to go bone dry. In the spring, as the growing season starts (or as soon as you see growth from forced bulbs), give enough water to keep the compost moist. Do not let the compost become wet or waterlogged - just moist to the touch at a finger’s depth is fine.
The stems will need staking when they reach about 30cm (12in) in height.
After forcing, bulbs should be placed outside to grow naturally with the seasons.