When do you start feeding tomato plants?

Hello Sarah & welcome to the Jungle. It's still a bit cold to be hardening them off just yet, having said that I put some in the polytunnel yesterday under fleece but I'm taking a gamble. As for feeding, I normally wait till I have a truss of flowers, some wait till they have fruited.

I always wait until I get the first flowers before I plant out. I feed when the first fruit appear.

I knew we could confuse Sarah between us..........................Sorry Sarah...........

Right ok, first flowers for feeding and planting out then. Thanks

Possibly......................

Welcome to the vine.
Two questions before I answer (I do like to be difficult) What size pots are they in? and what growing medium? Make that 3 have you transplanted them yet?

I always like to get them planted out before the first flowers appear,some flowers appear late & mine stay in a small 10cm pot until planting out in May or when night temps are above 12 degrees or so. I feed with tomorite when there are 3 or 4 trusses of flowers. I also feed with miracle grow plant food because it's in a small pot for a long time-fed them at 6/7 weeks the solution diluted 50% so it's weaker. I find if I don't do this the leaves start going yellow-lack of nutrients in the little pot.

My understanding is the the Books say not to feed until fruit can be seen (pin-head sized fruit where the flower was), but to pot on instead and that sufficient fertiliser is in the potting compost which, due to regular potting on, will nurish the plant.

I definitely do the potting on thing. 9cm pot, 1L, 2L, 3.5L and if they are getting very big a larger pot than that. My reason is that I get an incredible and dense root ball doing that, which is good for feeding. If planting in containers I would think it was essential (plat a small plant in a large container and its roots will grow outwards straight to the edge, and never form a dense rootball in the centre).

I don't rely on there being enough nutrients in the compost, but I don't feed much. I use a very dilute liquid fertiliser, just to make sure that the plant has enough (plenty of talk of cheap potting compost manufacturers skimping on nutrients ...) but the theory, in the books, is that some staring of Tomato plants encourages them to flower earlier - perhaps better put the other way that if you give young Tomato plants a lot of Nitrogen they will make loads of growth and not bother to start flowering

So I suppose:

If you pot on regularly (as soon as the roots fill the pot and start coming out of the bottom) then don't feed unless the plant looks poorly
If its stuck in a pot for any prolonged period then feed it.

One thing to watch out for is Magnesium deficiency. Happens to many growers, usually around the time that the fruit start to form, and in Tomatoes in particular. The old leaves start to yellow except for the veins which then appear to be very prominent (by comparison). Giving them some Epsom Salts fixes that (you would be better buying that at a Garden Centre, than a Chemist, as the Garden Centre sells large bags [which will last years] and the chemist tidily containers, but they both charge the same!!

How many of us never feed at all? I plant out into the greenhouse bed (enriched with good garden compost) and have enjoyed vigorous heavy cropping plants for twelve years without any extra food. From time to time I have given them nettle tea but stopped doing this when I really noticed no difference.

Outside the same applies, as I plant them into well composted soil. We have heavy clay which though terrible to work is very fertile, but our concern is always about blight rather than needing to feed for a heavy crop.

I tend to go along with those who say, feed the soil, not the crop. But I appreciate people growing in pots, grow bags or ring culture will need to feed.

It depends - if I pot on with new MPC then I do not feed until the first fruit appears then with a Tomato feed - if they are in pots for a long time or the compost is old then I use a more balanced feed with more nitrogen to encourage general growth.

Well that is if I remember

I am sure like others I over feed and water because we think we need to.

Last year I grew sweet n neat variety in containers filled with standard multi purpose compost. I fed them just twice and the harvest was still huge

I'm sloppy about feeding. Like you my soil is prepared with the aim of getting a good crop - plenty of compost and manure. I have Comfrey plants, so tend to mulch with leaves (rather than go to the trouble of making Comfrey Tea)

I do use a proprietary Tomato fertiliser (might you try that on a control-number of your plants?) from time to time, but never a liquid fertiliser and certainly never a big brand name like Tomorite - hugely expensive, if buying a liquid Tomato feed I would buy a Brand-X supermarket-own type.

My preference is something from Chempak - granular so a little more trouble to disolve, but a lot cheaper.

Price makes little difference for anyone feeding only half a dozen plants ... more than that I think its worth comparing the total diluted volume