Potatoes

Bake 'em, mash 'em, fry 'em...

Potatoes grow best when high temperatures are between 60-75°F and low temperatures are between 45-55°F.  The usual planting time in Central Texas is between the presidents’ birthdays roughly between February 12 and 22.  Planting certified seed potatoes, rather than grocery store potatoes, ensures that they are true to name and are disease and insect-free.

Potatoes prefer a fertile and well-drained soil in full sun.  They will not perform well in clay soil.  To prepare the soil, mix in plenty of high quality compost, up to 50% by volume. If a potato scab has been a problem in the past, choose a non-manure based compost.  The soil should be amended to a depth of 8 to 10 inches.  At the same time, mix in an organic high nitrogen fertilizer.  Because it is best to avoid watering between planting time and sprout emergence, water the soil a few days before planting.

You can plant small (about golf ball sized) seed potatoes whole.  Larger seed potatoes can be cut into pieces first, in order to be more economical.  Each piece should have at least 1 2 eyes and weigh 2 4 ounces.  After cutting, coat the cut surface with dusting sulfur to prevent rotting.  Allow the cut to scab over for no more than 1 2 days in a cool, well-ventilated location.  If the eyes begin to sprout before planting, then your potatoes are off to a good start!  Be careful not to break off the sprouts.

Dig a furrow 6 8 inches deep in the prepared bed.  Plant the seed potatoes 10 12 inches apart in the bottom of the furrow.  If potatoes have sprouts, plant with sprouts pointing up.  Cover the potatoes firmly with only 3 4 inches of the amended soil.  As described earlier, it is best to avoid watering during this time before the plants emerge, because according to the University of California this reduces diseases and increases yield.  However, if the soil becomes dry a few inches down, it is important to water.

Hilling Up: After plants emerge and grow to 5 6 inches tall, gently add soil up around the plants, leaving the top leaves exposed. Before “hilling up” the soil, clip off any leaves that look diseased or damaged.  Hill up again in 3 – 4 weeks so that the furrow is now completely filled with soil.  This allows the tubers to be completely covered with soil, preventing the skins from turning green and toxic.

Correct watering is crucial to a successful potato crop.  Many diseases thrive if the soil or leaves are too wet, but yield is reduced if the soil is too dry.  Feel the soil to determine when to water.  When the soil is dry a few inches down, and a few plants begin to wilt slightly, it is time to water.  If you use overhead water, be sure to water early in the morning so that the leaves will dry quickly.  Sufficient water is especially crucial as the tubers begin to form, starting about one month after planting.

  • Fertilize again every 4 6 weeks with a high nitrogen fertilizer.
  • To nudge our alkaline soils towards a lower pH, you can also sprinkle coffee grounds on top of the soil every couple of weeks, or apply soil sulfur every 3 months or so.
  • In addition, you can boost plant growth and condition the soil with regular applications of a liquid fish emulsion fertilizer.

Harvesting: It’s enjoyable and educational to begin digging up a few potatoes throughout the season, starting about two months after planting.  Such new, uncured potatoes with their thin skins do not store well, and should be eaten soon after harvesting.  Most varieties show that they are fully ready to harvest by the yellowing and dying of leaves, but by test digging you know for sure.  When the potatoes are mature, it is time to prepare the potatoes for storage.  This process of curing the potatoes thickens the skin and allows potatoes to be stored for months.  Water the potatoes one last time.  A couple of days later, cut off all the plants at ground level.  Eight to ten days later, dig a couple of test potatoes.  If the skins are tough enough, harvest.  If not, wait a few more days.  Harvest carefully with a garden fork to avoid damage.

Storage: Eat any damaged ‘taters first and do not store them, as they can spoil the whole bunch.  Lay out undamaged potatoes in a single layer on a flat or cardboard box in a well-ventilated area for a few days.  Thereafter, they can be packed more densely.  They store best in a cool (40ºF), moist, well-ventilated, and dark location.  Some varieties can be stored in these ideal conditions for months. Enjoy!