Potatoes perform best in areas where summers are cool (65 F to 70 F), but are widely adapted. Potatoes
require well-drained soil. (They will rot under prolonged cold, wet
conditions.) If your soil is poorly drained or a heavy clay, consider
using raised beds. Adding organic matter (compost, cover crops,
well-rotted manure or leaves) is a good way to improve soil before
growing potatoes. Go easy on organic matter sources high in nitrogen
(such as manure) and nitrogen fertilizer as too much nitrogen can
encourage lush foliage at the expense of tuber production.
Unlike
most vegetables, potatoes perform best in acid soil with pH 4.8 - 5.5.
Use scab-resistant varieties with pH above 6.0. Because most other
garden vegetables perform best at near-neutral pH, it’s usually not
feasible to grow potatoes in their preferred pH range, unless you
dedicate one section of your garden to growing just potatoes in
rotation with cover crops.
Buy certified disease-free seed
potatoes from garden centers or through online or mail-order catalogs
for best results. If you save your own seed potatoes, discard any that
show any signs of disease. Avoid planting potatoes from the supermarket
because they may have been treated with sprout inhibitors. They may
also be less vigorous and more prone to disease.
Cut seed
potatoes that are larger than a chicken egg into pieces about 1 inch
across or slightly larger. Each piece should have at least one “eye”
(the bud where the stem will grow from) -- preferably two eyes.
Egg-sized and smaller tubers can be planted whole.
Traditionally,
cut seed potato pieces are allowed to cure for a few days to a few
weeks before planting. This is because the cut potatoes need high
humidity, plenty of oxygen and temperatures between 50 F and 65 F to
heal quickly. If you have excellent, well-drained soil that meets those
conditions, you can plant the seed pieces without curing. But if
conditions are not right, the seed potatoes will rot in the ground.
A
less risky practice is to put about 5 pounds of cut potatoes into a
large grocery bag and fold the top closed. Keep the bag at room
temperature for 2 or 3 days, then shake the bag to unstick pieces that
may have stuck together. Let sit for another 2 to 3 days and then plant.
If
you want fast emergence, keep the bag of cut potatoes at room
temperature until sprouts appear. Some varieties are slow to break
dormancy and benefit from a 2- to 4-week “pre-warming” before planting.
Others sprout in just a few days.
Plant about 2 to 4 weeks before
your last frost date. The soil temperature should be at least 40 F. Do
not plant where you've grown potatoes, tomatoes, peppers or eggplant in
the past 2 years.
One common way to plant potatoes is to dig a
shallow trench about 4 inches deep with a hoe. Place the seed potato
pieces with their eyes up (cut sides down) about 8 to 12 inches apart
in the trench, and replace soil. Space trenches about 2 to 3 feet
apart. Stems and foliage should emerge in about 2 to 4 weeks, depending
on soil temperature.
When the plants are about 6 to 8 inches
tall, “hill” the potatoes by hoeing soil loosely around the base of the
plants to within about an inch of the lower leaves from both sides of
the row. Repeat in about 2 to 3 weeks. You may want to make additional
hillings, gradually building a 6- to 8-inch ridge down the row.
(Hilling keeps the developing potatoes from being exposed to sun, which
turns them green and bitter. Green potatoes contain a chemical,
solanine, which is toxic in large amounts.)
Alternatively,
snuggle seed pieces shallowly into the soil and cover with a thick
layer of clean straw or other weed-free mulch. Add more mulch as needed
to keep light from reaching potatoes. (A foot or more of mulch may be
required.) Tubers grown this way can be easily harvested by pulling
back the mulch after the plants die.
A third method if you have
excellent potato-growing soil is to plant seed potatoes 7 to 8 inches
deep and skip hilling or deep mulching. The potatoes are slower to
emerge, but this method requires less effort during the growing season.
Deep planting is not good in cold, damp soils and it requires more work
to dig the potatoes at harvest.
Potatoes need at least 1 inch of
water per week from either rainfall or deep watering. Mulching helps
retain moisture. Keeping the soil from drying out also helps reduce
scab.
Use row covers to protect from Colorado potato beetles,
leaf hoppers and flea beetles. Crush the yellow eggs of Colorado potato
beetles on the undersides of leaves. Remove adults by hand.
