Maturity of a variety is often described as
early, mid-season and late. Differences will occur between regions but the
general rule of thumb that I follow is early - 60 days, mid season - 90 days,
and late - 120 days measured from the time of planting until harvest. Potatoes
will emerge anywhere from 3-5 weeks after planting. It is important to have
frost-free days from the time of emergence until harvest.
Whole seed can be Green Sprouted (Chitted)
prior to planting, this will ensure earlier emergence. 2-3 weeks prior to your desired planting date place your potatoes in a well lit area of the house, but not in direct sunlight. 16 Degrees Celsius is ideal.
Instead of producing long sprouts like those you will find during the spring in your cellar, the potatoes will produce strong short green sprouts which will be ready to grow into plants as soon as you get them in warm soil.
Typically for early season varieties you will receive 6-10 potatoes per kg. you can cut these and get 14-16 individual hills per kg.
Mid and late season will average between 7-14 potatoes per kg and we would only recommend cutting the larger seeds. anything smaller than a golf ball is typically not cut.
Fingerling varieties can be as high as 16-18 potatoes per kg, yet usually rage around 12-16 per kg.
What is the best seed spacing when planting?
The machinery on our farm is set up to plant the potato rows 3ft apart (1m). It seems far when you are planting, however by mid July the canopy of the plants will touch between the rows creating a solid mat of potato leaves.
How much space between potatoes within a row depends on the variety.
Early varieties can be planted close together
(6"-10"), as they tend to have a low number of tubers per hill. Planting them close restricts the nutrition and light each plant can access, which helps to
keep the size of those nice new potatoes to a minimum. Or if you want the earliest potatoes at the market, plant early season potatoes 12" apart, green sprout before planting and use a floating rowcover.
Mid season varieties are generally planted 8" to 12" apart. Late Season Varieties & Fingerling Varieties should be planted 12" or
The following varieties are considered susceptible:
Banana, Shepody, Agria and Yukon Gold
The following are considered moderately resistant:
Kennebec, Norland, Russet Burbank, Pacific Russet and Purple Viking.
It is possible to amend the pH of your soil using both organic and no-organic methods. The ideal pH for potatoes is between 4.8 - 5.5, which is slightly more acidic than most vegetables prefer. In less Acidic soils, potatoes are more prone to scab.
A number of people have asked about scab.
Bacteria that are present in most soils cause scab. The incidence of scab is
dependent on the following factors: variety, soil, pH, and moisture.
-High levels of organic mater increase the
risk of scab, regardless of variety. If you have added large quantities of
straw or manure to your garden site you have raised the percentage of organic
matter and raised the risk of scab. Recently tilled pastures usually have higher levels of organic matter.
-Sandy soil, which is low in organic matter, has a low risk of
-Dry years tend to be worse than wet years for scab. Scab only affects the
appearance of the potato and does not affect the eating quality of the flesh of
-In a dry year keeping the
soil moist with watering is an excellent tool to reduce scab.
Growing without Synthetic Fertilizers
It has been 6 years that we have grown potatoes in our market garden without any fertilizers. It is possible to obtain yields similar to those archived with the use of synthetic fertilizers, it just takes a little more work.
There are a couple options. Adding compost to the garden and mixing it in well is the easier option, if you have a good source of compost. Unfortunately I can not give you advice on how much to add to your garden as all compost will have different levels of nutrition.
Growing a cover crop "green manure" the year before you plant potatoes and tilling that into the soil. Legumes are often recommended as cover crops. Many of the vegetable seed companies now sell cover crop mixes that are great for building organic matter and improving soil nutrition.
This is also the first year that we will be distributing an organic nutrient mix for vegetables. There is a granular and liquid fertilizer. It is reccomended to use both, granular at planting combined with a liquid application every 2-3 weeks during the growing season.
Potatoes are heavy feeders. We have spent the last couple years phasing out the use of fertilizers in our Seed Potato Fields. For those looking for a good synthetic blend, this is what we were selling prior to our organic transition. 21-22-6-5. Important Micro Nutrients are .5% Boron and 1% Magnesium. It may be hard to find a fertilizer that contains this exact mix, do not worry. This formulation is only a base line that commercial potato growers use to maximize production. An important component to a good synthetic fertilizer mix is a combination of both readily available and slow release nitrogen. Too much nitrogen early on in the growth will result in an excess of leaves and plants lacking in tuber growth. It is also essential to test your soil and get a proffessional opinion on nutrient requirements. All soils are different and have varrying requirements.
Mix in your nutrition. It doesn't matter if it is compost or synthetic fertilizers, it is very important to add your source of nutrition then stir up the soil where you will plant your potatoes. It is not healthy for the plants to be in close contact with excess amounts of concentrated minerals.