Iris Growing Guide
Crop Rotation Group
Rich, fertile soil with excellent drainage.
Excellent. Most popular garden irises are hardy to -32C (-25F).
Topdress with rich compost in mid spring, after new growth appears. Fertilise with a liquid fertiliser in midsummer.
Showy iris blossoms look especially beautiful when they rise above the foliage of low-growing flowers with fine-textured foliage such as lobelia or sweet alyssum.
Single Plants: 30cm (11") each way (minimum)
Rows: 20cm (7") with 35cm (1' 1") row gap (minimum)
Sow and Plant
Set out plump rhizomes with a fan of foliage attached in spring, just as new growth appears, or in early autumn. Plant shallow, so that the rhizomes are barely covered with soil. Allow 30cm (12in) between large-flowered bearded irises. Siberian iris roots should be planted 15cm (6in) apart.
Our Garden Planner can produce a personalised calendar of when to sow, plant and harvest for your area.
Iris may not bloom for a year after they are moved. Choose early and late-blooming varieties to extend the iris season. Several newer varieties will re-bloom in the autumn with good care.
Cut irises for arrangements as soon as the buds show good colour; they will continue to open indoors. As the flowers fade in the garden, trim them off with scissors or secateurs.
Several insects damage iris roots. When digging and replanting an old plot, cut away pieces of injured root. Siberian iris have few pest problems, and are seldom eaten by deer.
Planting and Harvesting Calendar
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