February and March are the months to grow potatoes in the Bay Area. Local nurseries carry a good supply of certified disease-free fingerlings and large seed potatoes. Many of the varieties can only be enjoyed by the home gardener as grocery stores do not carry them. Speaking of which, never grow potatoes from the grocery store as they have been treated with a sprouting retardant and the results are disappointing.
To save space in your garden, try growing potatoes in a container. It should be at least 15 gallons and about 24” tall. It can be a metal or plastic garbage can with drain holes, a terracotta pot or a commercially produced heavy duty fabric or plastic potato bag. Let your imagination run wild!
There are many benefits to container grown potatoes and one is that you don’t have to worry about crop rotation or soil-born pests and diseases because they will not be grown in garden soil. Plus they are easier to harvest.
Planting: To prepare the larger seed potatoes for planting, cut them in half or thirds leaving two eyes per piece. Now leave the pieces, cut side up to air day on a tray for about 24 hours or overnight. Small fingerling potatoes can be planted whole. There are different theories on how many seeds to plant in a container and I have read you can layer them in lasagna style. In a 15 gallon container I would plant three or four fingerling potatoes or large seed potatoes cut into three or four pieces.
Start with a layer of 3” to 4” of good potting soil in the bottom of the container mixed with a couple handfuls of an organic starter fertilizer. Nestle the potatoes into the soil, cover with a couple more inches of soil and tamp down gently. Water well and wait for the green leafy sprouts to push up through the soil. If you are using the lasagna style now is the time to nestle another three or four seed potatoes amongst the plants and add more soil. As the plants grow, add soil around them, leaving only about 3” of plant showing. This is called “hilling”. You can also use straw, hay, partially composted leaves, or regular compost for hilling.
Potatoes are formed above, not below the seed potatoes. Each time you add the ‘hilling” material, mix in a handful of organic vegetable fertilizer to keep them well fed. Keep on hilling until the soil or other material is a couple inches below the top of the container. Don’t over fill it because you need room at the top to add enough water to thoroughly saturate the container.
Water and Fertilize: Keep your potatoes well watered once or twice a week depending on the weather and after you have finished adding soil or straw or other hilling material and the green shoots are at the top, fertilize once a month with an organic vegetable fertilizer. Potatoes need a steady supply of nutrients and the frequent watering in our warm climate washes the fertilizers through the container which is true of most all potted plants.
Harvesting: “New” potatoes can be harvested soon after the plant starts flowering, but you must be careful when you peek or harvest to not damage the plants. Mature potatoes are harvested after the plant tops die down. Always make sure the potatoes are covered with soil or other material or they will turn green. Green potatoes are mildly toxic and should not be eaten. Store your potatoes in the dark at about 40 degrees.
The experience of harvesting your own potatoes is like digging for treasure and once you grow your own you will always want to include them in your garden.
