E Potatoes - Growing Tips
Plant early to mid-season varieties. There is a list on the "what to grow" page. Plant shallow so the potato stays in the warmer soil. You don't need to hill the early varieties, but you do need to keep the tubers covered with soil. If they are exposed they start to green and eating the green parts is not recommended. Plant more densely than the package recommends maybe 4 potatoes in 1 square foot. If there is a sprout, bury it. Our gardens are typically dry and It may not be possible to over-water potatoes. They do seem to tolerate being densely planted, but you can not walk over the area where the tubers are, if you do the skin will split. After harvesting, if you plan to store the potatoes, don’t wash them, let them sit for a few days. This will allow the skin to toughen up. The skin of the potato contains good nutrition but you should ensure you have removed all the bits of soil. Our soils tend to have more metals than you want to eat. Check out the soil test results on the locations page.
Maturity? 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, midseason - 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. Late season potatoes are not recommended for here.
Cutting seeds into pieces and planting the pieces? This is optional. Cutting is not recommended. It spreads your seeds further but introduces a higher risk of disease. If you do cut your potatoes disinfect the knife after each cut using a 10% bleach solution. Leave at least 2 eyes (sprouts) per piece.
Chitting? Whole seed can be chitted (green sprouted) prior to planting, this will ensure earlier emergence and may allow you to delay planting. Potatoes are heavy feeders, if you have adequate moisture, add 4lbs of a 7-7-7 fertilizer per 25 feet of row. Planting shallow encourages early emergence especially if the soil is cool. This also reduces the occurrence of Rhizoctonia (Black Scurf).
When to Plant? How warm should the soil at planting time be? The soil temperature should be at least 5°C. Ideally the soil temp at the depth that the seed piece will be placed should be 10°C. It is also very important that the temperature of the seed piece is close to being the same as the temperature of the soil at planting time.
Scab? Bacteria that are present in most soils cause scab. The incidence of scab is dependent on the following factors: variety, soil texture, soil PH, and moisture. Some varieties are more susceptible than others are. There are no varieties that are completely resistant to scab. Russets seem to be less likely to get scab than other varieties. The following varieties are considered susceptible: Pontiac, Shepody and Yukon Gold The following are considered moderately resistant: Kennebec, Red Norland, Russet Burbank and Viking. More information about potato scab is available http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/faq6699 The higher the level of organic matter the more 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. If your garden is on an old farm site and happens to be on the site of an old straw pile or manure pile your risk of scab is very high. Sandy soil, which is low in organic matter, has a low risk of scab. Dry years tend to be worse than wet years for scab. Lower PH reduces scab. Scab only affects the appearance of the potato and does not affect the eating quality of the flesh of the tuber. Yield is not generally affected by scab. In a dry year keeping the soil moist with watering should reduce the amount of scab.
Spacing? What is the best seed spacing when planting? It depends on the variety. Early varieties can be planted close together (4"-8"), as they tend to have a low number of tubers per hill; this helps to keep the size of those nice new potatoes to a minimum. Midseason varieties can be planted 8" to 12" apart. Late season varieties should be planted 12" or more.