[A Reyt Tayty]

Now this may be one crazy idea, but here goes:
I've had no success with the tommy seedlings this year. Some of the seed was saved, but some was new this year. Both have failed, so I'm thinking it's probably not the seed. All sown in a mixture of compost, loam, and vermiculite. All failed. Tried different levels of watering, all failed. Tried brand new peat compost with a bit of vermiculite and a layer of vermiculite on top: either failed, or very poor. In a last ditch effort to try and raise a seedling, I've tried the peat compost on it's own. The results look promising from both the new and the saved seed. Could it be the vermiculite that is causing the problems?

[Goosegirl]

Could it have been that the vermiculite was holding too much water for the seedlings to cope with?

[RaptorUK]

Where were they kept ?  window cill ? propagator ?  greenhouse ?  perhaps it's just a bit warmer now and that is the difference ? 

Tomatoes need some warmth to germinate.

[A Reyt Tayty]

Germinated on a SW facing window sill. The seeds germinated within a few days. As soon as the first true leaves showed, the seed leaves withered and dropped off. Yesterday the last remaining few of a sowing made over a month ago threw the towel in. They only had a very poor showing of true leaves and there was no sign of any growth. The funny thing is, the stem looked quite healthy, even though very thin for a plant of their age. One single deep root, right to the bottom of the pot; no branching out of roots.

[RaptorUK]

Germinated on a SW facing window sill. The seeds germinated within a few days. As soon as the first true leaves showed, the seed leaves withered and dropped off. Yesterday the last remaining few of a sowing made over a month ago threw the towel in. They only had a very poor showing of true leaves and there was no sign of any growth. The funny thing is, the stem looked quite healthy, even though very thin for a plant of their age. One single deep root, right to the bottom of the pot; no branching out of roots.

Maybe they are damping off . . .  small seedlings don't use much water and if you have no bottom heat water won't be lost rapidly due to evaporation.  Warm moist conditions are ideal for the fungus that causes "damping off".

[Trillium]

What could be adding to possible damping off is the use of the compost. My personal experience shows that compost with germinating seedlings is just too rich and water retentive, and contains certain bacteria that new seedlings can't yet cope with.

Either try a proprietary starter mix, or eliminate the compost and ease up on the watering. Just little watering as needed rather than regular flushes.

The SW window could also add problems with too much direct sun and burning the young leaves.

[A Reyt Tayty]

Yes, I thought it might have been a bit bright and hot. But on really hot, sunny days, they have been protected from direct glare with some thin opaque polystyrene wrapping such as found around electrical goods taped to the window.

The watering is a funny 'un. I've watered from the bottom, but only when the compost seems to be drying out. If the top seems too dry, I just damp it very finely. Today, I inspected the contents of one of the pots of one which curled its toes up today. From the weight, I would have said there was pleny of water. On emptying, it was drier than I expected, but far from properly dry. I'd have said it was just right tbh.

[Goosegirl]

Could it be a combination of all three? I water from the bottom too, but lift the pot first even if the compost surface looks dry and see if it still has some weight in it. Whilst the top is dry, the roots further down will still have access to enought water to keep them going.

[A Reyt Tayty]

One last shot at the cause:
The only other common denominator is the fact that I've sown them all in clear plastic cups. Too much light for the roots? Promoting conditions for bacteria to thrive? I've noticed that the inside of the pots soon goes green. The seeds germinate ok, but don't get past a couple of weeks old.

Abject failure with moneymaker, tigrella, roma, g delight, black cherry. Anyone beat that?

[jezza]

hi is the vermiculite horticultural grade or from a builders merchant thats used for packing behind fireplaces ,we use a multipurpose compost without any additives germination was 86 plants out of 90 seed they had bottom heat and showed in 4 days ,do you use fresh tap water or out of a water butt ,seedlings can get damping off disease with water from butts if its been stood over winter and gone green jezza

[A Reyt Tayty]

Brand new verve from B&Q.
Fresh tap water.
The latest batch I've done appear to be holding their own, but I'm not holding my breath.