Perparing Seed Potatoes For Planting

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Photo of seed potatoes Seed potatoes are potato tubers that are
being used to grow a crop

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Seed Potatoes

Seed potatoes are the edible potato tuber that you use for everyday consumption. I’m sure everyone has at one time or another seen the white sprouts growing out of your stored potatoes, this is the potato going to seed. The point on a potato where all this sprouting action is going on is the potato eye.

Photo of newly sprouting Seed Potatoes

Photo Right - These potatoes have started sprouting in storage. If the time is right for planting a week in indirect sunlight will green them off nicely.
Mouse over image to enlarge.

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Seed Potato Selection

Certified seed

When purchasing potatoes to use for planting, it is best to buy from certified growers. Certified seed potatoes are certified disease free and true to variety. Using potatoes from the supermarket or any other un-certified source has a risk factor and is generaly not recommended. Also potatoes from this source have often been treated to prevent sprouting. Starting with quality seed potatoes is the essence of a successful potato crop.

Seed Quality

Regardless of your source of seed potato, before they are planted check them thoroughly for quality. How does it go?, rubbish in, rubbish out, Quality always counts.

The obvious rotten ones are of course the first to be disposed. often it is your sense of smell that will alert you to the not so obvious ones, these are sometime hard to detect until the rot is well advanced because the rot usually starts from the inside. If you have ever put your hand into a bag of potatoes and broken into a rotten one you’ll know what I’m talking about.

Your seed potatoes should be clean skinned without excessive blemishes, brown or soft spots. Splits, cracks, rough bumpy or warty looking. These are usually signs of one of the many potato diseases.

Photo of XXX

Photo Right - The cut in this potato has already started to rot and if planted will deteriorate very fast.
Mouse over image to enlarge.

Cut a few open and check for signs of disease. One of the most common ones you will strike is potatoes with dry, reddish brown rot in the flesh which is caused by late blight.

The best quality check is to think if you would want to eat it, so, If you wouldn't eat it - Don't plant it.. If any are shrived and soft, most of the nutrients are gone and they will make poor seed potatoes.

Photo of XXX

Photo Right - These potatoes are well "greened" but are shriveling due to both low humidity and being left too long before planting. A few of these in your planting wont matter much, but if too big a percentage of your seed is shriveled the total yield will be lower than with better quality seed.
Mouse over image to enlarge.

Using Your Own Seed

For the average gardener using your own seed is often very tempting but unless you have an heirloom variety that you want to keep it is probably not a good idea. If you feel the strong desire to use you own seed be cautious and scrutinize the intended seed potatoes for any sign of disease.

Avoid growing a crop of potatoes or any member of the nightshade family in the same place for three years. Crop rotation is important for gardening in general, but becomes really important if saving your own seed and especially important for both potatoes and tomatoes.

Seed Storage

Potatoes store best at 40 F (4 C) whether you have saved your own seed or purchased seed keep the potatoes at that temperature until you are ready to prepare you spuds for planting.

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Pre-Planting Seed Potato Preparation

If you are looking to get an early start to the potato growing season, or even for later plantings, you can pre-sprout your potatoes, often called “greening” or “chitting” before planting. They will be ready to plant outside as soon as conditions become favorable enough for growing. Your potato plants will be rocketing towards the harvest at light speed.

Greening or Chitting Potatoes

Potatoes store best at between 40 F (4 C). When planting time rolls around, you can induce sprouting by raising the temperature of stored potatoes to room temperature or at least above 60 F (10C)

Keep the humidity high to prevent the potatoes from drying out to much and shriveling up. Shriveled potatoes will often still grow and produce but production will be poor.

Lay out your potatoes in a single layer on the floor, planting tray or flats and expose them to indirect sunlight. If you have a large amount, the trays can be stacked on rakes or similar, as long as there is good ventilation and equal light. Let the potatoes sit in that warm environment for a week or two, until the eyes start to sprout. The sprouts will start to green up and should grow to at least 1/2 inch (13mm) long

Photo of greening or chitting seed potatoes

Photo Right - Seed potatoes layed out in flats being greened ready for planting.
Mouse over image to enlarge.

Short stout greened sprouts are reasonably tough and can be handled without being broken. If the potatoes have started sprouting in the dark they will likly be too long for good greening, it is best to rub them off and let them sprout again under the correct conditions. Long sprouts are much more delicate and are easily broken off during handling and planting.

Photo of greened seed potatoes where the sprouts are too long making them very delicate

Photo Right - Some of these greened seed potatoes have sprouts that are very long and quite delicate, these will be hard to handle and while they will grow without a problem there is the danger of them being broken off before they are planted causing you to lose the advantage of greening the seed.
Mouse over image to enlarge.

If planting is delayed for any reason you can slow down the sprouting process by keeping the potatoes to around 50 F (10°C) until you can plant them.

Warming Seed Potatoes

For planting large area of potatoes, pre-sprouting might not be practical due to the extra time and care needed when handling pre-sprouted potatoes. However even for larger plantings you can gain some benefit from warming them. This is a simple matter of bringing your potatoes out of the cool storage environment into a warm area a week before planting. This will break the dormancy stage of their cycle and prepare them better for quick sprouting once they are planted.

Cutting Seed Potatoes

Large potatoes with three or more sprouts can be cut in half. However make sure they have enough time before planting for the cut surfaces to harden or callus, 10-14 days. Spring time in most areas is typically wet and planting seed that hasn't healed properly can cause them to rot before the emerging plant has had time to form a good root system.

Photo of cutting seed potatoes before planting

Photo Right - When cutting seed potatoes ensure all pieces have good healthy sprout. There are two schools of thought over cutting seed potatoes, those who do , swear its good and those who don’t swear its not.
Mouse over image to enlarge.

Sulfur in powdered form is often applied to cut potatoes to hasten healing. It is apply to the cut area and allow to dry. The sulfur is applied by, either sprinkled onto the cut portion of the potato or by putting some sulfur into a paper bag with the cut potatoes, and shaking the bag to coat the cut surfaces. Lay the cut pieces out in single layers to dry for 3-4 days.

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True Seed

Growing potatoes in the home garden is usually done by using potatoes tubers as the seed rather than true seed.

Potato seeds or true seed is the small seeds found in the green fruit that form after the potato plant has finished flowering. Although it is possible to grow potatoes from these seeds it is not the norm for the average home gardener.

For the next page in this section follow this link to Planting Potatoes

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