In the Iris Garden: The Weed of the Month Club

A beautiful iris garden in Monterey Bay that does not belong to the Weed of the Month Club!

     While dating myself since the various products of the month clubs seemed to have all disappeared, I used to joke in talks to groups that I belonged to the Weed of the Month Club. By that, I mean that weeds are opportunistic—get the tall ones under control and watch the short weeds move into that spot. Over the years, I have found 4 specific weeds to be the greatest problem here: morning glory, spurge, nut grass, and dock. Each have their specific problems and require different approaches to keep them under control.

Every beautifully groomed garden needs a great iris--my favorite new to me iris this year--Jerico Springs

     Morning glory (Calystegia ) arrived at this yard in mushroom compost that I had bought to build up the soil in the back of the yard. So often trying to solve one problem results in the arrival of a new issue. Roundup was suppose to be the cure all for morning glory, but like most panaceas it turned out to be less than was promised. Morning glory is amazingly vigorous—its roots have been found 10  feet down into the ground in trenches and morning glory seed can germinate for more than 10 years. Once in the garden, eradication is not really going to happen, so the focus has to be on keeping it under control. I have learned to never let morning glory flower since that only exacerbates the problem. Having reduced the morning glory infestation to sprigs here and there, I use a small quart spray bottle with Roundup and that does work.

     Spurge (Euphorbia maculata) is another weed that is not only a total pest, but requires immediate attention. After letting it get out of hand for a couple of years, I have found that the best solution is to nip it at ground level when it just has a few leaves. My tool of choice is an O-ring hoe; the sharp 0-ring is perfect for spot weeding. Unfortunately the manufacture seems to be out of business and I keep having to replace the handle, but that is a small price to pay for spurge control. Last year I thought I really had spurge on the run. One day I was cleaning the walk when I noticed what seemed to be spurge, but not the normal all green clone that I usually find. Yip, my spurge now has a brown and green clone that is hard to spot—once again the high hopes of eradication have been dashed.

     Nut grass (Cyperus rotundus) arrived in the yard by hiding in the roots of iris rhizomes that had not been properly and thoroughly cleaned. There was a time that I despaired that the nut grass was beyond control, but then I found Manage (no longer made, but I continue to use it up since one ounce was only slightly less expensive than a ounce of gold). At first I had to use the Solo backpack sprayer over large areas and Manage does work, though slowly. It translocates slowly to the roots and the nuts, so the kill is gradual over 3-4 weeks. Years into the battle, I am now down to hitting nut grass with the small spray bottle, but total eradication is most likely a phantom.

    Dock (Rumex crispus ) was in the yard when I moved here and in recent reading, I learned that the young leaves are eatable, though I am not sure why anyone would want to eat it. The county agriculture inspector told me that the solution was hoeing them off at the ground or Roundup. With its long, branched taproot, hoeing only seems to encourage more growth and Roundup seems to be the best solution if applied with great care. I've had to use the Solo backpack on large areas, but now I am back to the spray bottle since I can drip Roundup on dock leaves around irises without spray on the iris leaves.

     With all chemicals, correct application is vital. Roundup will “tulip” iris flowers, so any time that I use it over a large area, I wash off any nearby iris foliage when I am done; Roundup damage does not seem to be permanent, but the loss of good bloom for one year can be hard to take—I did a major round of cursing the neighbors a few years back when 40% of the iris bloomed with Roundup damage to to their gardener using it for everything and anything. When using Manage, Manage splash seems to interrupt the correct expression of color in irises and daylilies, but the effects wear off within a few months.

     No matter how hard we all try, the weeds will always be with us. It does not help, either, if you have neighbors who allow their weeds to grow unchecked—on the east of the lot, I fight the encroachment of Bermuda grass from that neighbor; on the west of the lot, the avid gardener has given up any effort to control weeds (or snails, but that is another story) and I have to watch for nut grass sprigs invading under the fence. Just as we have the pageant of color in the garden starting in the spring, we also have the pageant of weeds to entertain and disgust us.

Another lovely, weed free garden at Napa County