These last three weeks have been busy here as we’ve been planting out ten research plots for our potato plant study. We are comparing the growth, labor, and yield of five different potato-growing ideas: trench and hill, straw mulch, newspaper-and-straw mulch, containers, and towers. In order to help others reproduce our study or grow potatoes using these techniques, we are providing detailed instructions on our plant-out methods. The next post (Lab Note 2.02) will describe how to care for the crop.
Trench and Hill
This is the traditional way to grow potatoes and is still used in industrial agriculture. A 6-in-deep trench the width of a shovel is dug through the growing bed (usually along the longest dimension). The fill from the trenches should be piled neatly along one side of the trench. Space between trenches should be 2.5–3 ft. Seed potatoes are placed in the bottom of this trench at approximately 1-ft intervals with growing eyes facing upwards (we planted eighteen tubers in three rows; total weight was near 3 lb). The traditional way to do this is put down the first potato and step into the trench with one’s heel almost touching the potato, then the next spud is dropped in front of the toe. The second foot steps in front of this potato, and the process continues, using the length of a foot to space the tubers.
Once in place, the tubers are covered with a generous scoop of compost each. We used Purple Cow Organics Activated Compost and applied about 3 lb per spud. Then a bale of straw is used to mulch both the trenches and hills of soil between the trenches to a depth of 4–6 in. This is about one bale of straw per 24 ft of trench. In this case (and the following methods) the straw should be watered in to keep it from blowing away before the next rain. As the plants grow, the hills of soil will be moved over to cover the new growth.
This method is popular among permaculture gardeners (among others). It is just like trench and hill, except without the trench and hill. A weeded plot is covered with rows of potatoes spaced 3 ft apart. Each row has potatoes spaced 1 ft apart and covered with compost. Then the whole thing is mulched with straw. That’s with potatoes place right on the surface — no digging. This is supposed to work best with well-established beds and/or rich soil. We did eighteen tubers in three rows weighing around 3 lb. Each seed potato was covered with about 3 lb of compost and one bale of straw mulch covered 24 feet of row. As plants grow, more straw is added instead of the traditional hilling.
This method is identical to the straw mulch method (potatoes on surface) except that layers of newspaper are laid down between the rows to suppress weeds. In our case, we added two layers of newspaper. It is best to wet down the newspaper as you go, otherwise it blows around. The newspaper goes over the ground, potato, and compost but under the straw. As it is wet down, the newsprint suffocates weeds below it. Be sure to use plain old newspapers, not magazines, as the former are made of recycled materials with soy ink, while the latter have chemicals to make glossy pages. As plants grow, more straw is added instead of the traditional hilling.
Containers are one way people without access to garden plots can grow potatoes on a patio or other mobile location. They are thought to create a good growing environment because it is more controlled by the planter. They also allow the plants to be “hilled” up higher as one can add mulch to the growing plant to make it taller. One can buy purpose-made growing containers (such as these — provided only for a visual example), but we were able to get grain bags from Wisconsin Brewing Company. These 50-gal bags had a plastic liner, which I tore out. Then these are rolled down until they’re only about 8 in high. A scoop of soil is put in the bottom, followed by the seed potato, compost (we used 3 lb), and a generous handful of straw. The ground around the containers is mulched with the remaining straw (we used one bale per 24 feet of row; we had three rows of six plants each, for a total of eighteen tubers weighing around 3 lb). As plants grow, more straw is added instead of the traditional hilling.
In the last decade, potatoes have been grown in towers made out of tires, wood, wire, or other media. The idea is that a tower allows the gardener to mulch the plant up to a few feet above ground, giving it a greater area of roots to produce spuds. Our potato towers measure 2 × 2 ft (l × w) and start out at about 6 in high. As the potatoes grow, more boards are added to the sides, bringing them up to a total of 30 in high. The towers are set in place, making sure they won’t shade out any other plants. Three or four seed potatoes are placed in the tower (we did eighteen spuds weighing about 3 lb total distributed in five towers) and each gets a scoop (we used about 3 lb) of compost. The whole layer is then heavily mulched with straw and the spaces around and between the towers are also mulched to keep down weeds. As plants grow, more straw is added inside the towers.
“Lab Notes” are a series of posts chronicling the progress our research projects. Research Project No. 2 is the testing of potato-growing methods. These notes may be useful for anyone interested in reproducing and testing our results. Others might be interested in just growing potatoes, and videos and other formal publications that will result from this research project will be posted to the website as they are available.