Veterans of composting have a wonderful store of knowledge that provides an advantage when beginning their Lasagna Gardening beds. Composters know how to fix problems commonly created when materials decompose, and know how to avoid them in the first place. The trick is to remember to apply the experience you have. The following are good tips to get you started.
Edging for Small Beds
I have had Lasagna Gardening beds that were as narrow as 4” wide. Smaller beds need edging to be contained. Since these beds are all raised beds, they tend to “wash away” at the edges in heavy storm or even watering. This might not be a problem in a large bed as you can just plant far enough away from the edge. But in a small bed, every inch counts. Use edging to keep materials in the bed.
Chop or Crunch Materials
I have found that if I put whole materials, water tends to shed away from the plant roots rather than being evenly distributed in the bed, just as it does in a compost pile. For instance, if I put whole leaves in the bed, they tend to mat together and water is channeled out to the nearest opening between leaves. However, chopped or shredded leaves are not as likely to mat and disrupt water absorption. An added benefit is that the surface area of chopped or shredded leaves is smaller, so they are not as likely to be picked up by a breeze and blown around the garden.
Use Different Sizes and Shapes of Organic Materials
Just as when you build a compost pile, a good mix of sizes and shapes in materials will create open air pockets for air and water to move through. Matting, and the resulting blockage of air and water movement, is minimized. Mixing soil, sand, or compost with materials helps with water absorption and retention.
Deeper Beds Are a Better Bet for Tap Rooted Plants
If a plant has a long tap root and it is planted in a shallow Lasagna Bed, the root will grow horizontally once it reaches the original dense ground. It’s better to build a deeper bed for these plants so their root systems have space to grow down.
Collars for Plants with Woody Trunks
Decomposing organic materials should never be allowed to lie in contact with woody trunks. If you are growing bushes, trees, or other plants with woody trunks in lasagna beds, I recommend you place a collar around the trunk to keep organic material away from the trunk. Make a collar with a disposable nursery pot. Cut out the bottom, then cut the cylinder open to make a vertical seam. Wrap the collar around the bottom of the trunk so that it does not touch the trunk and fasten closed with a clothespin or other fastener. This will leave a pocket of air around the trunk even if decomposing materials in the beds are moved around by wind or water.
Keep Plant Stakes Handy
If you are growing tall plants of more than 2 feet, I recommend you have some plant stakes handy. Because the roots are growing in decomposing organic matter rather than solid earth, their root balls can be pulled out of the bed in strong winds or if they become top-heavy. You can also provide more soil and finished compost at the base of these plants so they have a better chance of grabbing into the soil and holding on.
Collect Extra Bags of Leaves in Autumn
As time marches on, your beds will manifest volume reduction just like your compost piles do. Chopped materials must continually be added as mulch on top to replenish the bed. If you do not do this, roots will be exposed and dry out. The easiest materials to store and have on hand are leaves. Crunched leaves tend to be heavy enough to sit on top without blowing away in spring winds, but dry grass clippings are not.
Adding Sand to Organic Beds
I periodically add lava sand, greensand, and medium-coarse construction sand to my beds. Lava and greensand are rich in minerals but are more expensive than constructor’s sand. Earthworms don’t have teeth so they use sand to help grind organic materials. I have noticed that beds that have sand added periodically have more earthworms.
There is no set schedule when sand is added to my beds; time and funds available usually drive the decision. I add lava sand and greensand once or twice a year and add construction sand 3 or 4 times a year. There’s no need to mix it in, simply sprinkle the sand on top in a 1/8 to ¼” layer. If I’m expecting heavy rains, I tossle bed materials just enough so the sand drops down in the bed and there’s no danger of it washing out.
The construction sand I am referring to is the sand sold for cement-making. Years ago I used sand made for children’s sandboxes to mix into my soil with compost (before I had lasagna beds). One day someone told me that play sand was “too processed for earthworms” and I should be using cement sand. I tried it just to prove them wrong, but lo and behold, earthworms seem to like construction sand. There was a noticeable increase in earthworms in the soil with construction sand.
For bulbs that continue to bloom year after year, I have found it best to plant before building the lasagna bed. If the bed already exists, pull apart the organic material and plant in original soil underneath the bed. The reason for this is that bulbs that are in the organic material are very easy for little critters to get to and eat, and I think that the type of decomposers they are exposed to are more damaging to them than those found in the soil. At any rate, I have more luck with bulbs planted underneath the beds rather than in them.
Mary Tynes, Master Composter, www.mastercomposter.com