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NathanP · July 9, 2017

NarnianGarden, don't give up hope. I failed in multiple ways my first year growing TPS. It IS different than growing tomatoes from seed, so you certainly are not unique in your experience. My first year I lost all be 3 of about 180 seedlings. And only one of the three produced a tuber, and that wasn't worth keeping.

There is a learning curve to it, but once you figure it out, it isn't too difficult. The plants are smaller, and more fragile than tomatoes, so they do need to be treated differently, especially when small. A few things I would recommend, that I learned the hard way:

1 Use sterile germination mix, not potting soils, and not organic mixes. The potting soils and organic mixes have living organisms in them, which can contribute to damping off.
2 Another thing to prevent damping off is to only water from the bottom, not the top, once seed has germinated. This encourages the seedlings to root deeply. The top of the soil needs to remain dry.
3 Use liquid fertilizers, and feed from the bottom, just like watering.
4 Let the soil dry out. Water no more than twice per week if the growing area is not dry. I grow mine in my damp basement, so I only water once per week.
5 As soon as they germinate, get them under as bright sunlight or daylight bulbs. And get the bulbs as close to the leaves as possible. I lower mine to <1cm above the leaves for several weeks, and then raise them incrementally to 1cm above the highest leaves.
6 T8 bulbs are the minimum intensity bulbs you should use. T5's are better, and the more bulbs the better. T12's don't really produce intense enough light for TPS seedlings. They can be grown with T12's but plants tend to look spindly.
7 Germination can take more than 2 weeks with some TPS seeds. Germination tends to vary quite a bit depending on seed age and variety. Some are 4-5 days, others may take 3 weeks. Patience is needed to allow time for them to germinate. Seed under one year also does not germinate well. Germination inhibitors tend to delay germination until the seed is 2 or more years old. I still germinate 1 year old seed, but just expect lower germination rates.
8 Germination rates without chemical treatments can vary from 5% to 90%. I tend to average about 60% germination, with probably 40-50% if it is one year old seed. Seed older than 10 years may not germinate well unless it had been frozen.
9 Seedlings like to be transplanted at least once - I do this at about 4-6 weeks, burying all but the top layer of leaves. This allows the plant to root more deeply and develop more layers of roots. It can be done earlier, but plants are more fragile when smaller. Some people like to transplant several times during the first 8-12 weeks. I sometimes will transplant into the same size container, I just stuff the plant in lower and coil the roots and stem lower.
10 Seedlings often take 10-12 weeks after germinating before they are ready to transplant outdoors. When they are 4-6" tall, they are usually ready.
11 Most TPS seedlings will take longer to grow in the first year than in subsequent years when grown from tubers. Early varieties sometime senesce and are growing tubers by 8-10 weeks, and often tubers from these plants are quite small in the first year. It does not necessarily mean they will produce low yields when grown from tubers. The correlation to make is that they are early varieties and will bulk earlier than most plants.
12 TPS seedling hills rarely have yields of more than 1 lb. Some do, but those are rare, and most of those are ones that last 150+ days before senescing. That does not necessarily mean they will produce more than other TPS plants that senesced earlier in the same year. It is difficult to gauge yield until you regrow the tubers of each seedling.
13 I have come to the conclusion that, with some exceptions of highly inbred high yielding lines (not what I want), it is probably unrealistic to expect high yields with plants grown from TPS in the first year. That does not mean it is not worth doing, and anyone that truly likes playing around with genetics and experimenting can find TPS growing quite satisfying. It just means that TPS evaluation is really just not a one year evaluation.
14 Expect a percentage of seedlings to die. I used to want to baby every plant, but have gradually come to the conclusion that the ones that die are self selecting themselves out of the genepool, for various things. I want plants that can handle drought and don't need babying, so I do not water once I plant them. The ones that die failed to thrive, in my growing conditions. This points to one of the main advantages of growing TPS seedlings, that you can select for the ones that do well in your local environment, with all your local climate conditions.

Hope that's helpful. Feel free to ask any questions, as well.

July 9, 2017	#8
NathanP Tomatovillian™ Join Date: May 2013 Location: RI Posts: 183	NarnianGarden, don't give up hope. I failed in multiple ways my first year growing TPS. It IS different than growing tomatoes from seed, so you certainly are not unique in your experience. My first year I lost all be 3 of about 180 seedlings. And only one of the three produced a tuber, and that wasn't worth keeping. There is a learning curve to it, but once you figure it out, it isn't too difficult. The plants are smaller, and more fragile than tomatoes, so they do need to be treated differently, especially when small. A few things I would recommend, that I learned the hard way: 1 Use sterile germination mix, not potting soils, and not organic mixes. The potting soils and organic mixes have living organisms in them, which can contribute to damping off. 2 Another thing to prevent damping off is to only water from the bottom, not the top, once seed has germinated. This encourages the seedlings to root deeply. The top of the soil needs to remain dry. 3 Use liquid fertilizers, and feed from the bottom, just like watering. 4 Let the soil dry out. Water no more than twice per week if the growing area is not dry. I grow mine in my damp basement, so I only water once per week. 5 As soon as they germinate, get them under as bright sunlight or daylight bulbs. And get the bulbs as close to the leaves as possible. I lower mine to <1cm above the leaves for several weeks, and then raise them incrementally to 1cm above the highest leaves. 6 T8 bulbs are the minimum intensity bulbs you should use. T5's are better, and the more bulbs the better. T12's don't really produce intense enough light for TPS seedlings. They can be grown with T12's but plants tend to look spindly. 7 Germination can take more than 2 weeks with some TPS seeds. Germination tends to vary quite a bit depending on seed age and variety. Some are 4-5 days, others may take 3 weeks. Patience is needed to allow time for them to germinate. Seed under one year also does not germinate well. Germination inhibitors tend to delay germination until the seed is 2 or more years old. I still germinate 1 year old seed, but just expect lower germination rates. 8 Germination rates without chemical treatments can vary from 5% to 90%. I tend to average about 60% germination, with probably 40-50% if it is one year old seed. Seed older than 10 years may not germinate well unless it had been frozen. 9 Seedlings like to be transplanted at least once - I do this at about 4-6 weeks, burying all but the top layer of leaves. This allows the plant to root more deeply and develop more layers of roots. It can be done earlier, but plants are more fragile when smaller. Some people like to transplant several times during the first 8-12 weeks. I sometimes will transplant into the same size container, I just stuff the plant in lower and coil the roots and stem lower. 10 Seedlings often take 10-12 weeks after germinating before they are ready to transplant outdoors. When they are 4-6" tall, they are usually ready. 11 Most TPS seedlings will take longer to grow in the first year than in subsequent years when grown from tubers. Early varieties sometime senesce and are growing tubers by 8-10 weeks, and often tubers from these plants are quite small in the first year. It does not necessarily mean they will produce low yields when grown from tubers. The correlation to make is that they are early varieties and will bulk earlier than most plants. 12 TPS seedling hills rarely have yields of more than 1 lb. Some do, but those are rare, and most of those are ones that last 150+ days before senescing. That does not necessarily mean they will produce more than other TPS plants that senesced earlier in the same year. It is difficult to gauge yield until you regrow the tubers of each seedling. 13 I have come to the conclusion that, with some exceptions of highly inbred high yielding lines (not what I want), it is probably unrealistic to expect high yields with plants grown from TPS in the first year. That does not mean it is not worth doing, and anyone that truly likes playing around with genetics and experimenting can find TPS growing quite satisfying. It just means that TPS evaluation is really just not a one year evaluation. 14 Expect a percentage of seedlings to die. I used to want to baby every plant, but have gradually come to the conclusion that the ones that die are self selecting themselves out of the genepool, for various things. I want plants that can handle drought and don't need babying, so I do not water once I plant them. The ones that die failed to thrive, in my growing conditions. This points to one of the main advantages of growing TPS seedlings, that you can select for the ones that do well in your local environment, with all your local climate conditions. Hope that's helpful. Feel free to ask any questions, as well.