GROWING TECHNIQUES FOR IRISES

These charming, colourful plants may be grown in several ways. Where room is available they look well grouped in beds or borders of irregular shape. Where there is less room they may be grown among other plants such as in the herbaceous border. They do best in a sunny, open site, but preferably one which is not exposed to wind as their brittle fiower stems, which normally need no staking, are liable to be broken by strong winds.

The plants will remain in the same position for a number of years before they have to be lifted and divided. Although they are not gross feeders they grow best in a reasonably rich soil. They do not like fresh manure and by far the best material is garden compost well distributed through the soil when it is being dug. The soil should be further enriched by working coarsely ground bone-meal into the top few inches at the rate of 4 Oz. to the square yard. If the soil is not naturally limy or chalky a dressing of hydratcd lime may be applied at 2 to 3 Oz. to the square yard. Good drainage is essential and efforts should be made to improve the drainage of heavy clay soils to prevent them from being water-logged in wet weather. This can be done by digging them deeply and by adding such materials as sand, sharp weathered ashes, straw or compost.

These tall bearded irises grow from a rhizome, the botanical name for a swollen underground stem from which buds arise. This is not a root, but roots appear from it, usually on the underside. This gives a clue to the method of planting. After the soil has been properly dug over and a fine surface tilth has been obtained by breaking down the clods, it is necessary to prepare a planting hole for the rhizome. This should be deep enough and wide enough to allow the true roots to be spread out properly. But do not make it too deep.

The aim should be to have the top of the rhizome just showing through the soil when planting has been completed and the soil around it firmed. The spread-out roots will anchor the plant as they will grow rapidly. Rain will wash some of the soil off the top of the rhizome, leaving it exposed to the sun. In this way it will receive the baking which it likes and will respond by sending up young fans of leaves and flowering stems from the buds which develop along it. Although iris rhizomes may be planted at almost any time there are two main seasons for planting. These are early spring and in the summer, immediately the flowers are over and from then on until September. In summer the ground is often dust dry and it is difficult for the plants to get a proper root-hold. This can be overcome by soaking the rhizomes in water for a day and then planting them in boxes of moist peat, leafmould or sand to encourage the rapid formation and growth of new roots. Then, when planted out in the previously prepared site the plants will get away much more quickly.

Propagation is by division of the rhizomes. Old-established plants make a confused mass of branching, overlapping rhizomes. These should be lifted every three or four years after flowering is over, using a garden fork to prise them out of the ground.

Iris rhizomes should be planted with the top just showing above soil level.

The rhizomes should be lifted every 3 or 4 years and divided. The younger outer portions should be re-planted.

The centre of the clump will probably be dead or dying and these portions should be cut away first. Then the younger outside portions may be cut up into pieces each with-its fan of leaves. The long, old leaves may be shortened to a fan shape before the divided rhizomes are replanted. This is not essential but is often done, particularly as these leaves often die back from the, tips after the operation of lifting and dividing.

The centre of the clump will probably be dead or dying and these portions should be cut away first. Then the younger outside portions may be cut up into pieces each with-its fan of leaves. The long, old leaves may be shortened to a fan shape before the divided rhizomes are replanted. This is not essential but is often done, particularly as these leaves often die back from the tips after the operation of lifting and dividing.

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