by Cindy Kerson

I'm back again to report on the progress of the Kurapia replanting area. The original post in Spill the Beans was on December 6,2021. The saga began in April of 2020 when we laid Kurapia (Lippia nodiflora) sod. Over the summer months, it looked beautiful, but we noticed a lot of Kentucky bluegrass (Poa pratensis) growing in spots. It continued to spread, as bluegrass is known to do, a positive aspect if one desires bluegrass. We didn't. We wanted Kurapia. After some discussion, our distributor graciously agreed to return the next spring and replace the sod. Spring of 2021 rolls around and we were in the midst of a profound drought. Once Kurapia is established, it needs very little water – maybe once a month from June to September. But initially it needs a good deal of water, applied frequently to get established. We decided to put off replacement another year. We hope to get more rain so it will be feasible for us to get it started.

Starting in November 2021, whenever we received a shipment with a big cardboard box, I started sheet mulching the area to be re-sodded. It took about 2 months to receive a sufficient number of usable boxes to cover the area. Over two days, I watered the area deeply so the cardboard would be very wet. Then I spread 4mm clear plastic over the top to solarize it. Solarizing is a way to kill unwanted weed seeds. According to UCANR, this is mostly true for annuals since perennials have deeper plant structures (roots, rhizomes) that are present throughout the year. They won't be as threatened by the heated upper layers of soil. The bluegrass is a perennial, so my experiment may not have killed it, but it should be effective against the other weeds in my soil. I think we got most of it up when we pulled up the Kurapia anyway. I get a lot of clover and I've been trained to not pick it since whenever it's shaken (by walking on it or pulling it out), it sprays seeds. In fact, if you get close to it, you can hear the tiny seeds being sprinkled. I recently learned that killing/removing weeds can be detrimental to our ecosystem since those weeds may be pollinizers and/or food and shelter for many insects that are in turn food for larger insects and vertebrates. For me, gardening is primarily to support nature and to provide food, but I am also guilty of manipulating it for my aesthetic comfort and as with everything – it is a balancing act.

I anchored the plastic with either metal garden stakes or rocks. I hope they withstand any winds we have and am curious about what will happen when it rains. That area is on a very slight slope, and I wonder if water will puddle and render the plastic too much of a mess to reuse, since I try to use as little plastic as possible. When the new Kurapia comes, we'll remove the plastic and lay the sod right over the sheet mulched area.

There is a second smaller area that we will re-sod where we did not put cardboard or mulch down. I was going to spread compost, but when we dug up the remaining Kurapia, mostly dead or dormant, the soil was so dark from the compost we put down 2 years ago that we simply put plastic on top. We didn't want to put down mulch because we likely would have had to rake it all out in a few months when we laid the new sod since it would not decompose in time. Just like everything in my garden, it is an experiment. I wonder if the cardboarded (I had to convince spell-check that that is a word) area will do better than the un-cardboarded area. Stay tuned. I'll post next if and when (pray for rain) the Kurapia sod is installed this spring.

Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143.  Volunteers will get back to you after they research answers to your questions.

Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.

Photo credits: Cindy Kerson

Information links:

Oregon State Univ.-sheet mulching (lasagna composting) https://extension.oregonstate.edu/gardening/soil-compost/sheet-mulching-aka-lasagna-composting-builds-soil-saves-time

UC Davis-Kurapia https://ccuh.ucdavis.edu/kurapia