Cultivation
Spring-flowering bulbs are ideal for growing in pots, in a mix of two parts John Innes No 2 potting compost to one part grit or coarse sand. Whether in containers or the open ground, most bulbs should be planted at three times their depth and one bulb-width apart, to allow for spread.
Keep pots of small bulbs watered when in leaf. As the flower buds swell, move the pots to where they can be appreciated such as near the house, in a cool porch or even on a windowsill indoors in a cool room. To promote good flowering next year, feed the bulbs every seven to ten days with a high-potassium fertiliser such as a liquid tomato feed. Begin feeding as soon as shoots appear.
Destroy bulbs that have yellow mottled foliage: this usually indicates an incurable virus infection.
Post-flowering care, lifting and dividing
Pots of bulbs brought indoors to enjoy should be put in a sheltered spot outside as soon as flowering is over. Reduce watering once the leaves begin to die down. In the ground, mulch shade-tolerant bulbs such as some Muscari and Scilla persica to stop them drying out when dormant. Top up gravel mulches around bulbs in alpine beds.
Where bulbs are congested, flowering performance can decline. Lift and divide when they are dormant, after the foliage has died back. Carefully lift the clumps with a trowel. Discard diseased or undersized bulbs and replant the remainder into soil improved with organic matter. Upturn pots and tap the rim to release bulbs in containers.
Some bulbous species such as Eranthis (winter aconites) and Galanthus (snowdrops) are traditionally moved or divided ‘in the green’, when flowering is over but they are still in leaf. Opinions differ on whether this is a better method than moving when fully dormant.
To aid bulbs to spread, allow seed capsules to develop on crocus, Eranthis, snowdrops and bulbous iris. The seeds can be collected and sown fresh, or left to self-sow.
Spring is also a good time to remove bulbs spreading too far. Grape hyacinth (Muscari armeniacum), for example, spreads rapidly by seed and bulbils. Discard bulbs in the green-waste bin rather than on the compost heap.
Naturalising in grass
Many spring-flowering bulbous plants grow well in grass. Do not mow from the time the bulbs first emerge until the leaves begin to yellow; premature defoliation weakens the bulbs and can reduce flowering performance the following year.
Suitable species and cultivars include: Crocus chrysanthus and its cultivars ‘Blue Pearl’, ‘Cream Beauty’ and ‘Snow Bunting’; Crocus sieberi; C. tommasinianus; Narcissus asturiensis; N. bulbocodium (damp soils only); N. cyclamineus and cultivars ‘February Gold’ and ‘Peeping Tom’; Anemone nemorosa; Chionodoxa luciliae; Eranthis hyemalis; Erythronium dens-canis; Galanthus nivalis; Scilla siberica and S. bifolia.