Iris Holl. Royal Yellow

Both. Some Iris, including Dutch and dwarf iris, are grown from bulbs, while bearded Iris are supplied as rhizomes, which are thick horizontal stems. Always check the product label, as bulbs need to be planted deeper whereas bearded Iris rhizomes sit close to the soil surface.

Plant spring-flowering Iris bulbs in autumn, ideally from September to November, for flowers the following spring. Plant them as soon as possible after delivery in a sunny position with well-drained soil. Bare-root Iris rhizomes have different planting times, so follow the instructions supplied with your plant.

The usual causes are not enough sun, overcrowding, waterlogged soil or incorrect planting depth. Bulb Iris needs a sunny, free-draining site, while bearded Iris rhizomes need their upper surface warmed by the sun rather than buried or covered with mulch.

Yes. Iris bulbs grow well in pots with drainage holes and free-draining compost. Use a deep enough container, place it in full sun and avoid allowing the compost to remain wet through winter.

Yes. Most garden Iris are perennial and return each year when grown in suitable conditions. Divide established clumps when they become crowded or flowering declines, then replant the healthy sections with enough space to grow.