Tomato Growing Thread 2021

Any advice for feeding tomato seedlings with significant purple undersides of leaves? I've read this is caused by a phosphorus deficiency, which can in turn be caused by cold soil (unlikely as mine are in a warm cupboard), but I'm guessing as I've pricked them out they need a feed.

Any recommended brands of feed or phosphorus supplements for use in seedlings? I still remember the pain of using a quarter-dose of sulphate of potash on my strawberries once and burning literally every last one of them so I'm very wary about using fertilisers and getting it wrong...

 

Had them on right from the start. They're in a fairly warm cupboard (understairs, middle of the house) which runs about 25 degrees down to lowest 19 at night. Be aware they do increase the temperature of the space so cooler-weather crops won't germinate well under them (no success with spinach, had to move it to windowsill).

 

That can be caused by growing them under lights.

 

Hello - I've just joined Gardner's Corner just for this Tomato thread and I cant get enough of your fab posts and pictures : )

I have a question too. In 2019 I bought some of these Ledicia tomatos from Sainsburies - see picture. They were delicious. I kept seed that worked really well last year and have germinated really strongly again this year. They are a bit smaller (likely my set-up) but still just as delicious. I think they might be a heritage variety but I cant find any more information about them at all. Do any of you experienced growers have any suggestions? Or do you think a supermarket can take an existing variety and trademark a new name? Many thanks - sorry for long post.

 

Ooh ok, so possibly not a phosphorus deficiency? I'm guessing it's something that won't stop them growing and will disappear once they get into natural light?

I'm currently growing them under lights until they get to a certain height, then they get moved to natural light at a few weeks old.

Is it still worth feeding?

 

Maybe in the plants, but probably not in the compost. Tomato plants turn blue/purple after getting cold, because the chill causes a phosphorus deficiency, so perhaps the growlights also reduce/prevent the uptake phosphorus and adding more to the compost wont make any difference?

I time the indoor sowing of my tomatoes so that if they turn blue/purple (I have defective colour vision) the greenhouse heating goes on and they go in there where natural light sorts it out, and as that's the time I start running out of space indoors and I also want to start sowing all dorts of other stuff.

Another effect of growlights on tomatoes is something similar to sunscorch, and the varieties I've had the most trouble with are Sungold and Orange Paruche, so they are the last to go in. N.B. I use T5 lights, not LEDs (but thinking of adding a couple of large LEDs to my setup).

 

I always start mine under lights @FrancescaH and have noticed the purpling in previous years, but it usually resolves by itself when I move them outside in May. I've never worried about feeding until they flower and I can't say I've noticed any problems with the health of the adult plants at all.

 

Ok thanks FrancescaH I only normally put the lights on after they have sprouted but as its ok to use them from the sowing I can ad more tray of others things without worrying

 

Thanks for the tip - had a happy poke around and finished up with Brandywine and junior gold tumbler or some-such yellow bush cherry variety : ) [after I thought Id finished sowing for the year]

 

thank you

 

I'm 2 days ahead of you with my main sowing

 

I actually bought some small tomato plants yesterday.
Red alert , black cherry, sweet aperitif and garden pearl.
Apart from red alert I've not tried any of these before.