The fourteenth day of September is an important day for me or should I say it is an important day for my garden. September fourteenth is the day that I start to divide my irises. The iris is my favorite flower (see my photo blog Spectacular Irises ). Irises are beautiful flowers that will provide years of spectacular blooms but they do require a little care. With the proper care prized heirloom irises can be passed down from generation to generation. Besides proper planting the most important thing in order to have healthy and long lived irises is that they should be divided every two or three years. If they are not divided they may seem to be healthy for a number of years but eventually they become overgrown, susceptible to disease, and rotting. Left to their own devices the clump of irises that you love so may simply die out from neglect.
To divide irises first take the entire clump out of the ground using a large shovel or pitchfork. Place the clump on the ground and knock off as much dirt as possible. Once all the dirt is off inspect the plant for damage. If irises are left in the ground for more than a couple of years they will grow outward from old growth usually leaving an unproductive and possibly diseased or rotting center. Once you have identified the center of the clump break off or pull apart the individual rhizomes. A rhizome is difficult to describe but easily identifiable. It looks somewhat like a cross between a root, and a tuber. It has roots growing off of it and has a gnarly appearance. One of the main reasons for waiting until September fourteenth to divide my irises is that the eyes which will provide new flowers now begin to appear on the base of the rhizomes. The iris eyes look like small onion sets and may be a half inch in diameter down to a mere nubbin, just a tiny bump on the rhizome. If you have trouble identifying the eyes at least make sure you get a healthy looking rhizome with a full fan of leaves on it. Chances are it will have at least a developing eye on it even if you can’t readily see it. Once you have separated the rhizomes discard the unproductive center. Examine the separated rhizomes carefully for insect holes, rotted centers, and any other signs of disease and discard any that are doubtful. Once you have done this give the roots and leaves a haircut. The reason for trimming the leaves is to lessen the demands on the roots after the dividing process. Intuitively one would think that all the roots should be kept intact but giving them a quick trimming helps to promote the growth of the fine feeder roots during the fall and gives the plant a chance to establish a sturdy foundation before winter arrives. If you have any rooting powder or solution it helps to treat the roots to stimulate new growth. The last thing I do is to dust the wounds where I broke the rhizomes off with sulfur dust. This helps to prevent disease and infections of the wounded plant.
Next comes planting your new iris plants. This is probably the most important step in the cultivation of irises. Irises must be planted with the top half of the rhizome out of the ground and exposed to the air and sun. If irises are planted completely underground they will quickly rot and soon die. Like all plants irises need moisture to grow; but they need well drained and dry soil conditions, otherwise they will struggle to survive. If you have ever been working in your garden around irises and smelled a powerful stench that smells something between rotting flesh and rotting garbage you probably have encountered an iris that was planted completely underground in wet conditions. If you look closely you will most likely see that the center of the clump is rotting and if left unattended the entire clump will eventually die out. When planting iris rhizomes dig a hole large enough in diameter to accommodate the rhizome and deep enough that the roots have plenty of room. Once you have the hole dug, take some of the excavated dirt and form a firm mound of dirt as high as the level of the surrounding ground. Place the rhizome on top of the dirt mound and spread the roots out around it. Then backfill the hole around the roots making sure that the top of the rhizome is exposed. Pat the dirt firmly in place and water liberally. Do Not ! I repeat – Do Not fertilize the newly planted iris. The last thing you want to do with any perennial flower is to promote new leaf and stem growth going into winter. The new growth will not be strong enough to survive the winter and it decreases the chances of the new plant surviving into spring. If you just can’t resist doing something to help the plant grow you can sprinkle a little bone meal on the bottom of the hole before planting.
Dividing my irises can sometimes take a couple of weeks, After I am done with the irises I turn my attention to my daylilies. I divide my daylilies not for the health of the plant but for propagation reasons. While daylilies can be divided in the spring I have found that I get the best results dividing my daylilies in late September. There are two ways to divide daylilies. One way is to simply chomp down trough the plant with a shovel, or in the case of some of the larger daylilies use an axe or even a saw to cut apart the larger clumps. I prefer to dig the entire plant out of the ground and then looking for the natural forming smaller clumps within the larger plant. On smaller daylilies such as the Stella D’Oro you can identify and pull apart the divisions with great success. I have taken 5 or so Stella D’Oro daylilies and multiplied them into dozens of plants.
I have one last dividing tip for those of you who might have read my spring blog Butterfly Gardening. If you would like to have more butterfly bushes in your garden try the following method of propagation. Snip seven or eight pencil thick cuttings about six inches long from your butterfly bush. Be sure to make the bottom cut just below a leaf node on a forty-five degree diagonal. Make the top cut just above a leaf node, again on a forty-five degree diagonal. Tie the cuttings together with string and bury the cuttings about five or six inches deep in your garden. Mark the location of your cuttings in some way that will last through the winter so that you can find them in the spring. Resist the temptation to check on their progress during the early spring: leave them in the ground until late May when temperatures have risen and the ground has warmed. If you are lucky you may be rewarded with one or two new butterfly bushes.
Flower gardening doesn’t have to be and expensive affair. Using the division technique of propagating plants can not only save a lot money, it also provides a great deal of satisfaction.
Late September and early October is also the time to plant spring flowering bulbs, such as tulips, hyacinths, and daffodils. Plant the bulbs three to four times the height of the bulb. Adding a little bone meal to the bottom of the planting hole will help root growth and give the bulbs a head start heading into winter.
With a little work and some planning, you will be well rewarded for your efforts with a bevy of beautiful blooms next spring.