Dutch Iris Mixture

Dutch irises are a very popular cut flower and are easy to grow at home, flowering in September-October. The cut flowers last for up to two weeks. They were bred by Dutch flower growers from species Spanish irises and the Moroccan iris, I. tingitana, which has given the Dutch iris family its strong blue and violet shades as well as an earlier flowering time compared to Spanish Irises. Hybridising work over more than a hundred years has resulted in the wide colour range available today, from white to deep purple with bronze, pink, light and dark blue in between.

Dutch irises prefer a sunny, well-drained position in the garden, but will grow in semi-shaded positions as well, flowering a little later. They are reasonably hardy, although the soft flower buds can be damaged by frosts in early spring. They should be planted 8 to 10 cm deep in early to mid autumn. Soil should be worked up well to a depth of 15 cm before planting, to ensure easy rooting. No fertiliser is needed at planting time, and fresh animal manure should be avoided at all times as it promotes lush leaf growth with few flowers.

There is little to do after planting and watering the bulbs in. New leaves will appear from May onwards. Once temperatures are rising in the spring and growth is faster, it is advisable to spray occasionally to control aphids, which can quickly spread virus between plants. Natural Neem-based sprays provide good control. In humid conditions, fungal diseases can become established. A general purpose spray such as is sold for roses is also suitable for irises. If picking the flowers for indoor use, do so when the bud has emerged, but before it is fully open. The buds will continue to open indoors from this stage and with naturally grown garden irises there will usually be a second bud, which will emerge as the first begins to die back.

Try not to remove or cover the leaves after flowering - now is when the bulb is growing and gaining strength to flower next year, and the leaves are essential to fuel this process. The bulbs can be left undisturbed in the garden for several years, and will often flower better and earlier in their second or third year when they have become more established. Eventually they begin to produce more leaves and fewer flowers as they become overcrowded, they should then be lifted and separated. Wait until the leaves die back in summer before digging the bulbs in January. Dry the bulbs in a warm airy place, out of direct sun. Once they are dry, separate the offsets from the larger bulbs and remove any loose skins and roots. Store the bulbs at normal temperatures until replanting in autumn. The offsets will generally not flower in their first year as they need to build up more reserves, but will flower well from the second year onwards.