Two years ago we created a large border in our upper field using a technique called “sheet mulching”. I’ve written about it before. It’s the process of organically killing the existing vegetation by smothering it with other organic materials. We laid down a layer of cardboard and then newspaper followed by six inches of fresh grass clippings. The process works like this; over several months, the organic materials are devoured by earth worms and other soil creatures which loosen the soil and in turn add their castings to the soil enriching it and creating better structure. In other words, it becomes soft, rich and the best soil to plant in. We begin all of our beds this way.
For structure in the middle of the large border, we planted eight lilac bushes about three feet tall. We then continued to add organic matter such as leaves and stalks from annual bulbs we dug out for fall storage. In addition, whatever annual flowers that were heavy seeders such as elephant head amaranthus, cosmos, marigolds, and phlox were tossed into the bed and allowed to self seed right in the bed. The flower stems and stalks provided a mulch for the seeds and also kept the weeds down. It’s not very neat looking mulch, but we’re not a highly manicured garden, so it works perfectly for us.
We call our technique of adding organic materials on top of the existing flower bed “In-line composting” because it’s all done right in the bed, no need to haul mulch or add any compost, it happens naturally when everything decomposes right in the bed, and it’s easy and not time consuming either. The seedlings and plants grow right up through the old stems and leaves and their foliage covers up the old rotting materials.
The following spring, most of the stalks and stems were rotted down and we had a glorious riot of color by self seeded annuals. Even a few pumpkins showed up that year.
We continued to do the same thing last year and added even more seed bearing stems of both perennials and annuals to see what we would get this year. It seemed to work fine in early spring, as I saw many seedlings emerge throughout the whole bed. But unfortunately, there was a very late heavy frost that took out everything that sprouted including all of the buds on our wisteria and hydrangeas which are planted closer to the farm house.
This year it’s not as full as we had hoped, but thank goodness those elephant head amaranthus were very heavy seeders and right after the frost more seedlings emerged. The bed looks a little lopsided now, there are a few cosmos, morning glories, and one lonely sunflower, but I’m definitely confident that next year it will be a show-stopper.
Now is the perfect time to grab some seeds from your perennials and annuals and toss them around your garden to allow a more naturalized feel. Not all of them may survive, but it’s worth the extra few minutes to try. You’ll be amazed next spring when you have flowers coming up where you don’t even remember planting them. Sometimes nature has the best ideas so give up a little control and take a chance , you never know what perfect combination will occur.