Early planting of potatoes is important since they must grow and set tubers before intense summer heat arrives. Planting potatoes in March will improve yields. It is important to use a fairly large seed piece (2 oz.) since the larger seed piece will give you a good ‘insurance policy’ in case potatoes are injured by a late freeze.
With the larger seed piece, potatoes 12 inches tall can be frozen to the ground and still recover to produce a normal crop. However, a larger seed piece is not necessary. Cut an average sized potato in 4 pieces or a larger potato in 6. Try to get at least one “eye” or bud in every piece.
It is important to cut seed 2 – 3 days before you are ready to plant and store the cutseed in a warm, humid location with plenty of air circulation. The cut surfaces will then develop a ‘corky’ surface that has a slightly powdery appearance. This indicates the presence of suberin, a natural wound healing compound produced in the cut area to protect the seed pieces from rotting.
Don’t plant potato seed pieces too deep. Deeper planting will slow emergence. It is< best to plant them 1 to 2 inches deep to encourage rapid emergence. Then, gradually cover the row with more soil as the plants grow so that an 8-10 inch ridge of loose soil covers the row by the time the potato vines are fully extended.
Start Your Potato Planting With Healthy Seed Pieces
Remember that a few simple precautionary measures at planting will avoid disease losses later in the season. The most important thing you can do is to start off with clean, disease-free seed pieces. Purchase certified seed (blue tag) from reputable garden centers each year. Many bacterial, viral and fungal diseases are transmitted through the seed piece. Saving tubers from last year to be used as seed is asking for trouble. Certified seed has been screened against many of these vegetatively propagated diseases.
Make sure you frequently disinfect the cutting knife in a 10% bleach solution or alcohol when cutting seed potatoes into smaller pieces for planting. Some bacterial diseases are easily transmitted by the knife.
Try to pick a new planting site within the garden each year and make sure the seed pieces are planted in well-drained soil. Hill the plants slightly so that water doesn’t puddle around the seed piece. As the vines grow, mound up soil, covering the vine with just the tip remaining above the top of the mound. Do this until the mound is about 12 inches tall. Remember, potato tubers develop above the planted seed piece, not below it. For this reason, tubers need to be covered with soil at all times to prevent the greening of tubers that are exposed to sunlight. This green substance is called solanine, which is bitter and can make you sick if eaten in enough quanity.