Growing Concerns: Iris come in rainbow of colours, but not red

Some folks call them flag flower, but most refer to them as iris. They are named for the Greek word for rainbows.

The first iris arrived in gardens in 1913. Many of the bearded varieties originated in central and southern Europe and the beardless are from Asia.

The iris is best known for its connection to the French “fleur de les”. The fleur de les is a much more stylized version of the iris but there is no doubt they are related.

There are several types of Iris and even though they look somewhat the same they have different growing habits.

Bearded iris — also known as the German bearded iris — are the largest group with more than 2,000 varieties in a vast array of colours and colour combinations. The early blooming ones can be about 15 centimetres tall while late season bloomers can be about a metres tall.

Beardless iris includes the most popular Siberian Iris, which do very well in the shade. These have a smaller bloom but can be just as showy as their cousin. Blue is the most popular colour in these followed by yellows and whites.

Dutch iris are bulbs that are planted in the fall so they bloom in the spring.

There is yet to be a pure red iris, but the shades of blue, purple, pink, peach, yellow and white are endless.

Most Iris are grown from rhizomes right at the soil surface. About 1/3 of the rhizome is above the ground and the rest is below with very strong roots to hold the blooms upright. These rhizomes are not happy if they get mulch on top of them. They need the sun to keep the tops dry and prevent them from rotting. Over time, the centre of a clump of Iris will die off and new rhizomes will grow on the outer edges. It is important, every few years after the Irises have finished blooming, to dig them up  cut off the old, dried up, dead part of the rhizomes with pruners or a sharp knife, leaving young, healthier growth.

While doing this, it is a great time to inspect the rhizomes for iris bore, which is a worm about the size of a grub that feeds on the iris rhizomes. You should treat the rhizomes with beneficial nematodes in the spring and fall. If you find borers in rhizomes, drown them in a bucket of water with a bit of dish soap.

Plant the bulbs back in the ground in groups of about three rhizomes. Make sure the leaves point to the outside of the cluster. This allows for the rhizomes to expand and produce more flowers next year.

If you have iris, now might be time to clean up all the old rhizomes or maybe it is time to add a few to your garden for a focal point.

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