Irises come in almost every colour from yellows to oranges to reds to blues and purples. Some of them are quite small and others are larger and they do make a wonderful cut flower and many of them have wonderful fragrances as well. So, there is really a lot to recommend them.
They need to be pruned and divided every couple of years because if you let them grow into very large crowded clumps, they won’t bloom as well. Since they bloom in the spring, they need to be pruned in early autumn. That gives them a chance to adjust and grow and put on new roots and set blooms again for the following spring.
- Go around the clump very gently and just lift them and loosen them.
- Once you get the clumps out, set them aside and prepare the soil well.
- Add a little compost or a little balanced organic fertilizer.
- A rhizome that has bloomed the previous spring is not going to bloom again. You’ll know which those are because they’re the ones that look old and leathery. Those you’ll just cut away and discard.
- Look for iris rhizomes that are soft because that may indicate a bacterial disease, and if they have holes that look like burrow holes, you’ll definitely want to discard those — not in the compost, throw them in the bin.
- Cut off any of the new shoots of the rhizomes and those will be the ones that you plant again.
- Take a short pair of shears and cut those away and discard this old part.
- If you have any roots that are torn or ragged or shrivelled, cut those away.
- Keep the rhizomes moist until you get a chance to get them in the soil, cover them up with a wet sheet and put them in the shade as you are preparing them. They can stay out of the soil for a while, but it’s best not to let them dry out completely.
- Take a little dusting sulphur and dab the cut ends in it to help cut down on fungal and bacterial problems in the rhizomes and keep them healthy.
- Cut away any foliage that looks brown and discoloured. To do this take some very sharp scissors, and cut them in a chevron so that the upper leaves are pointed.
- Then you want to plant them, but not too deep. You want the surface of the rhizome to be level with the surface of the soil.
- Line the rhizomes up in the same direction and plant them in little triangles of the same colour.
Irises don’t need a lot of mulch. If you plant them properly and divide them occasionally you will have displays of colour that are just show-stopping.