My question is in the post heading. I have GTS colorful mix. I’m wondering if I should start all of them this year or can I spread it out a bit?
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They are viable for several years under good conditions, however I suggest starting a lot more than plants you want to end up with, so I wouldn’t hesitate to just plant all/most. Unless you just want like 5 plants, then you might consider planting 30-50 of the seeds.
I wrote something up that I should really send out, here it is:
Ideal Planting Date: Start seeds between March 18th and May 1 (they are slow as seedlings so the earlier the better). They need at least four weeks to grow before transplanting them outside. Plant 3-5 times as many seeds as you want seedlings for, and cover them slightly with soil (less than ¼ inch).
Planting Instructions: When choosing or making your starting soil, be sure to include native field soil in the mix, but as weed free as possible (forest soil). Potatoes need to build relationships with soil microbes to thrive from the first moment of germination, in fact the more microbes the better. Keep nitrogen levels low– seedlings will be less prone to disease (damping off symptoms) and legginess when they don’t have excess nitrogen, and lower fertility will encourage them to build mycorrhizal relationships early and have sturdier stems.
Germination is best under cool, damp and dark conditions. I put them on a shelf inside for the first seven days. Germination is best at 60-70 degrees, cooler than other nightshades. Germination may be slow– up to two weeks. After one week (or if you see any sign of germination) be sure to put them immediately in a bright spot with at least 8 hours of sunlight. As long as you have enough sunlight, grow lights aren’t needed. As they grow, give them plenty of outside time in the wind and sun to build strong seedlings with strong stems.
Be prepared for uneven and spotty germination, tiny seedlings, and slow growth. Unlike other crops, potatoes have not been selected to have strong seedling growth. That’s our job now.
This is what your seedlings may look like after a month, even if you planted multiple seeds per cell. Choose the biggest seedlings to up-pot or translant and compost the rest.
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Thank you that’s great info. I was wondering if you get full potatoes the first year or if you get little tubers the first year then plant those the second year? I looked it up and that is what I found. I’m excited to plant my true potato seeds this year!
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Very timely post. I started mine in potting mix, with no native soil, and put them on a heat mat. 
Normally people get micro tubers. The first year I planted TPS (the video of Joseph in my field in the course) I got some very big yields, but it’s never happened again like that for me. And yes you should keep your favorite micro tubers, I’ll write another letter about that, since you will need to taste test in the small chance you encounter a plant with bitter tubers.
The year I planted TPS, I got microtubers from 34 plants and small, but full-size (for that plant…it hasn’t increased the following year) tubers from one. It’s safest to expect microtubers that you’ll want to cellar and replant. But assuming you get enough, you could still cook and taste one for selection – the little tubers seem to be representative in flavor of the full-size ones.
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When the first year I group from true seed I got a mixture of medium sized potatoes to the small ones so I guess it’s just a question of conditions that they grow up in
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Germination this year has been good so far. This picture (today) is from a group that were seeded 03-17-24. Also overseeded quite a lot since we’ve been relatively unsuccessful with other TPS up til now. The GTS TPS is growing great for us so far. 
Didn’t do anything special to sprout them. Seeded this roll, put it in a tray in a window (it had other friends in the tray who appreciated light), and had it there until it sprouted 10 days later. Now it’s under lights with other potato friends. They get ambient room temp - the room is between 50-65F, occasionally up to 70F. When it’s not snowing and at least 40F, they get to go soak in the sunshine and feel the breeze on their hairy little stems for a few hours a day. 
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Hi, mine were sown on my hotbed with my eggplants ands peppers on the 19th of march, and sprouted about 10 to 15 days later. Temperatue was about 25°C, so about 75°F. Good germination rate so far. I did not know they could need lower temperatures. They were coming from Cathy and the “Croation Seeds Store”
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I have sown TPS from Croatian Seeds Store as well. Out of 9 varieties, four have germinated, but I have sown small number of seeds.
My impression is that they need more like 6-8 weeks before planting out, at least in my case. They are extremely tiny seedlings initially and they stay tiny for a very long time. Tomatoes are sprinters and giants compared to them.
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I agree with you @WojciechG. These are mine after 18 days from sowing, on a hotbed (20-25degCelsius)
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Lovely babies 
I guess I will sow some more this week, learning by doing 
I’ve got Cathy’s mix only and they’re an estimated 6 weeks in and some as big as smaller toms of the same age. I’ve had a bad experience with Vreeken’s Sarpo surprise that hardly did grow. SO it really matters where you get your seeds from. I think they’re in the seed train.
Just potted up the biggest tps plants of mine. Before and after pics. These are “clancy outcrosses” and “mixed tetraploid, red” from Cultivariable seed.
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