Taking time away from all that I am doing but.....TPS germinates from five days to as long as several weeks...the majority from 7 to 12 days. Potato seed--TPS- does not like to germinate all at once like tomatoes...some seed will last in the soil for another year. New seed will germinate slower than seed two or fifty years old. The soil temperature is important, too cool or too hot can be a problem. 72 degrees is the best temp, with 66 to 78 acceptable. Even temps day and night is required...a hot day in the greenhouse followed by a night in the 40's would be too much of an extreme
Because I sow lots of TPS as a rule, I start with a 72 cell insert put into one of those 11 by 21 inch trays. I use a sterile peat lite seed starter type media. I get the Organic growers mix 3.8 cu. ft. bale.
Sunshine Natural & Organic Aggregate Plus 3.8cf bale
SKU: SUGRMIX4NO
Weight: 82.0 lbs.
Package Dimensions: 26.0L x 16.0W x 14.0H
Suggested Retail: $43.95
Sunshine #4 Natural & Organic is recommended where high air capacity and fast drainage are needed: during winter months, with water or salt sensitive crops, or where frequent leaching is required.
I level the media off the top of the insert. Compress an indentation with my fingers to press the media down a fraction of an inch...1/8 inch? Then I sow one to 10 seed per cube depending on my objectives and rarity of the seed. I cover the seed with just a smattering of soil...1/8 inch or less...press it down again with my fingers. This firming down of the soil media allows one to water without flooding the media and floating off the media and seed. I water the flat in with 120 degree water to hasten the swelling of the seed coat.The competition helps germinate slow germinaters and the first to germinate helps the stragglers stretch to keep up. It is highly significant if you can give the seedlings intense light just as soon as they emerge in order to keep them stocky. Direct sunlight or florescent growlights within inches of the soil. 12 to 24 hours a day of light is critical....8 hours or less of light makes the seedlings spindly. Do not cover the flat with plastic or a lid...damping off...fungus...etc., is a common killer of potato seedlings. The soil should be moist but not wet and needs to dry out a bit between waterings. If you have a grow mat for germinating TPS...that is perfect for winter time, late Spring when the days are warm wouldn't need the grow mats.
As the plants grow one can tolerate the cooler nights but not below 55 to 65 ideally. Try not to exceed 80 degree days in the greenhouse. As seedling grow their 2nd true leaves and are about 2 inches tall---give or take----carefully transplant back into 72 cell trays...one plant per. The seedlings will not have many roots and breaking the root (s) happens often even with me. I even transplant those whose roots are totally broken and they often re-root. It is important to transplant into small containers because you don't want wet soil and a root ball must start within the confines of the one inch square cell. Be sure to bury the cotyledon and maybe one of the true leaves...leaving just a bit of plant above the soil to finish growing taller. The first transplanting occurs about three weeks after seeding.
I mix a stronger soil media by starting with the above Sunshine media and mix in worm castings, dolomite lime, compost, composted manure, bone meal, alfalfa meal, kelp meal, blood meal, greensand, rock phosphate, wood ashes, cottonseed meal, etc. Not too much but just enough to give the soil media some oomph.
Another two to four weeks later the seedlings should be about three inches high and if the flats are taken outside on some mild days to get acclimated to the sun for a few hours a day....this prevents transplant shock when you take them to the field or garden. I like to transplant to the garden in a shallow furrow and cover up another leaf or three so that very little of the plant is showing above the soil line. Water in and wait a week or two before bring a bit more soil up around the stem. I space seedlings about 10 to 12 inches apart within the row and my rows are at least three feet apart. I like 4 ft. so that I can walk between the rows and use a tiller close to either side of the row to work the soil. At a few more weeks go by, more soil is hilled up around the seedlings so that about four inches of soil is above the original root ball. The potato needs to have these frequest hillings to allow it to root in and within the dormant buds in the apex of the leaf stems...more above ground stems emerge out of the soil. And if no extra stems, the plant will shoot stolons out from those buried leaf attachments to form tubers. By bringing more soil up around the seedlings...one is eliminating weeds from taking over. If you till between the rows just before canopy closure....weed pressure is reduced to a minimum.
When to sow...?.5 to 8 weeks prior to your last frost. Canada last frost would be mid May or later. It is OK to start you sowing later or on weekly intervals all winter and Spring but the idea of putting the seedlings out after all danger of frost is past is to mimic tuber plantings.. We usually put tubers in the ground 4 to 5 weeks before the last frost. If one starts the seedlings too early like in February...the potato seedlings grow mature and reach a senescent state when the potato leaves start to turn yellowing and stop growing....thus tuberization has occurred. Once the seedlings start their first little tuber...there is but a short window to get them into the field. If the tubers grow for a while the seedling will die down and will not recover from the transplanting to the field. Only the late maturing ones will survive and grow into a full size vine. The ones that die down are the early maturing clones. The best time to transplant is when just a few of the seedling begin a tuber....and you'll know this when you transplant.
I am not going to go into watering and fertilizing....too many details...I will do that later on the website newworldcrops.com
Harvesting tuber hills can happen over a range of a month or more....I tend to dig those that die down early and leave the late vines go until frost sometimes.
