Sisal rope potato towers from agave fibers for no-dig spud yields in compact lots

To construct your tower in a compact lot, begin by driving four sturdy wooden or bamboo stakes into the ground to form a two-foot square. Use stakes that are at least four feet tall and 1.5-2 inches thick; anything flimsier will bow outwards under the weight of the moist growing medium. Drive them 8-10 inches deep for stability. This framework will support the structure. For a true no-dig start, place a layer of overlapping cardboard directly on the ground inside the stakes, making sure to remove any plastic tape first. This smothers existing grass or weeds without tilling and will decompose over the season. Wet the cardboard thoroughly to help it settle.

Begin wrapping the sisal rope, which is derived from agave plant fibers, tightly around the outside of the stakes. Secure the end to a stake with a solid knot before you start. Pull the rope taut as you wrap, starting from the ground level and ensuring each new layer presses firmly against the one below it to prevent gaps. A common beginner mistake is wrapping too loosely, which allows soil to erode during watering. Create a solid wall of rope about eight inches high. The coarse, natural texture of the sisal provides excellent containment.

Fill this initial section with a six-inch layer of a loose, well-draining mix. Avoid using heavy garden soil, which compacts and restricts tuber growth. A combination of 50% compost and 50% shredded leaves or straw works perfectly. Place three to four chitted (pre-sprouted) seed potatoes on top of this layer, with the sprouts or “eyes” pointing up. Space them evenly, a few inches away from the rope walls. Cover them with another four inches of your mix. Once the potato plants have grown six to eight inches tall, wrap another six inches of sisal rope around the tower and carefully add more growing medium, burying the stems but leaving the top set of leaves exposed. Repeat this "hilling" process as the plants grow. Towers dry out quickly, so check moisture daily by poking a finger two inches deep; water thoroughly when dry. When the foliage yellows and dies back, simply snip the ropes to harvest your potatoes.