The very cold weather may be giving the less hardy plants a tough time. But it's creating some great visual effects. Here's the frosted deadhead of Agapanthus…
Protect crowns in the winter with a mulch. Suitable for coastal conditions.
The plants will increase slowly but may be propagated by division in the spring. The plants may also be raised from seed in the autumn or spring (but cultivars will not come true from seed).
Pests, diseases or disorders
Slugs, snails and viruses may be a problem.