Growing Irises: Selecting and Preparing an Iris Bed

Selecting and Preparing an Iris Bed

Bearded irises are easy to grow and require minimal care.  They need well-drained soil and at least six hours of sun each day in order to bloom well.  Here we’ll describe how to choose a spot and prepare it.  No yard? No problem!  Irises can grow quite happily in pots on a sunny balcony or patio, and we’ll describe how to do that, too.

Choosing a spot:  You don’t need half an acre in order to have a beautiful iris garden!  Pick a location that gets at least six hours of sun every day and your irises will be happy.  If you are in a very hot climate, irises will enjoy a bit of afternoon shade.  Because irises grow in clumps, you can plant quite a few in a small space.  Plan on spacing your clumps 18″ – 24″ apart.  A sunny corner of the yard might be a great spot to grow three or four different clumps of irises.   Or you might have an area along a fence that gets a lot of sun.  If you are planting a bed of mixed flowers, you might consider putting irises in the back, as they tend to bloom earlier and grow taller than many other plants.  There are many companion plants that do well in an iris bed, and you can read more about them on our Companion Plants page.

Preparing the bed:  Don’t skimp on this step; it’s crucial to growing healthy, blooming irises.  Remove any grass, and dig down at least 12 inches to loosen the soil and remove any roots.  The more roots you can remove now, the less grass you’ll deal with later. If you really want to cut down on weeding, outline your bed with an edging strip before you plant.

Your soil needs to be well-drained, because irises are prone to rot if they sit in wet soil.  If you are dealing with heavier soil (lots of clay) then you will need to remove some of it and mix in some sand and compost to lighten it up.  There are about as many recipes for good iris soil as there are iris gardeners, but one that seems to work well is to aim for about 1/3 each of sand, topsoil, and compost or humus.  Many iris gardeners swear by gypsum as a soil conditioner for clay soils; other soil improvers include aged horse manure and alfalfa meal.  Mounding the bed will help with drainage and allow you to use some of the soil you removed.

Using raised beds: Many iris gardeners plant in raised beds.  The advantages are 1) the irises get good drainage and 2) you can create the soil conditions you want.  The downside is that you’ll need to back fill the raised bed, and that means you’ll need to bring in topsoil, sand, and compost.  If you have topsoil delivered, make sure it is screened to remove weeds and roots. You  might be able to have sand mixed with it before it arrives.  A 50/50 mix of topsoil and sand, with compost added in, will get you off to a good start.

Growing irises in pots: If you don’t have yard space available, you can still grow irises in pots.  The smaller the pot, the sooner you’ll need to divide them, and a minimum size is probably three gallons or so.  A five to seven gallon pot will allow your irises room to grow into a nice clump.  Make sure the pot has drainage holes in the bottom, and use the same soil  recipe as for irises grown in a bed.

Preparing your iris beds takes some work, but to paraphrase the late Henry Mitchell (a wonderful garden writer), “The time to get an iris through the winter is before you plant it.”  And you only have to do it once.  Now you are ready to choose  irises for your new garden.