Topic: Tomato Plants not growing

[Garden Manager]

Need to know if I have a problem or not. Seed was sown 18th March and the resulting seedlings were transplanted about 2 weeks later unto pots of standard multipurpose compost as I normally do. After the usual settling in period several don't seem to have grown that much at all (with a few exceptions) and a few have grown a bit and just stopped. I would expect them to be growing away strongly by now. They have warmth and good light and don't get chilled at night. Can't really work out what's wrong and what's best to do about it.

My only theory is that it's the compost but I have used this sort before and have always been happy with the results.

Any ideas/suggestions as to what could be going on or what to do about it? Thanks.

[Plot 18]

Can you explain a bit more about where they are - "They have warmth and good light and don't get chilled at night."

Just questioning as being even a tad too cold would explain it?

[Garden Manager]

Can you explain a bit more about where they are - "They have warmth and good light and don't get chilled at night."

Just questioning as being even a tad too cold would explain it?

OK. They are in my conservatory, which is double glazed. It has a small heater that ensures temp don't fall below about 10 -12c at night. Start them and lots of other plants off in this way every year, normally with no trouble. Often things do TOO well and are bursting to move on to the cooler unheated greenhouse before the weather allows them to!

[Plot 18]

You were right of course, about the conditions LOL

You could try giving them a weak liquid feed to see if they pick up, to me, modern composts seem to be lacking in feed, and I am feeding seedlings more often than I used to.

[Garden Manager]

Thanks. Not worth repotting into different compost? That's going a too far perhaps!

That said I have been trying out John Innes type composts with good results. Wouldn't mind trying the tomatoes in it.

[Tee Gee]

You could try giving them a weak liquid feed to see if they pick up, to me, modern composts seem to be lacking in feed, and I am feeding seedlings more often than I used to.

I agree I don't trust the producers of these new composts

Over the years they have cut back on bag sizes making the price of a litre of compost more expensive. Then they are making composts out of recycled materials, yet another way of cutting costs and maximising profits.

It was only a matter of time before Fertiliser content become their latest line of attack.

Unlike packets of Fertiliser which must show the NPK content they do not have to declare this with bagged composts.

Because I think this way I have found that the only way I can cater for the suspected low fertiliser content is to always water with a half strength liquid fertiliser at every watering.

Then speaking of watering I find I have to be more careful with the amounts I apply as many of the new recipe composts seem to look dry on the surface so one is tempted to apply water  and if I do succumb  I often find that the composts become water logged and the roots can't breathe, hence slow or weak growth.

I find quite often that I have to  resort to letting  my pots virtually dry out  then I give the half strength liquid  feed.

Obviously I have no proof of these practices but since the advent of low or peat free composts my suspicions have been aroused, hence these comments.

[Garden Manager]

Yes I have had similar experiences with composts in recent years. I also find they have become coarser and lumpier, and often need seiving. The compost I used for this year's tomatoes was the same make ss last year, but the texture and consistency seems different and it was very dry on opening the bag, it needed a lot of wetting.

[galina]

I had a similar experience a few years ago.  And came to the conclusion that the ph in the bought compost (was peat free) must have been way off.  As tomatoes generally need replanting at least once, this can be corrected with different compost, but I would leave some of the bad compost in place, not wash it off the roots.  Good luck

[ACE]

Nearly all of the peat free (recycled rubbish) can only really be described as soil conditioners. I perk mine up with growmore. I am not organic but if you are chicken pellets might be a better option.

[Garden Manager]

This is why I have decided to try John Innes type composts (See thread in 'The Basics' forum) as they should be more consistent. Wish I had thought of it when I was planting up my tomato seedlings.

Looks like a feed is in order then.

[Vinlander]

Yes, John Innes is the answer to composts looking dry and being wet - but you only need to add 10% to the modern stuff to 'wet' it enough to stop this completely. Unlike wetting agents it lasts forever - which I like because I microwave all spent compost (20min for 8L) in winter and use it for seed sowing next spring... I keep the fine stuff (for tomatoes, peppers) separate from the coarse stuff (for sweetcorn, peas, beans).

The other and/or solution is capillary benches.

I would still check the pH of the medium in a weird case like this.

How big are these 'seedlings'? Toms are tough - I find seeds will grow for weeks and reach 15cm quite happily in pure peat - to the point where I suddenly remember to break out the liquid feed or poke a hole and fill it with chicken pellets.

I bought a light/moisture/pH meter for a few quid about 8 years ago - it's accurate enough for gardening and the 'power' comes from the copper/zinc probes (and a tiny PV window).

Cheers.

[Garden Manager]

Have had a couple of the weeder ones out if their pots to look at the roots. Hardly any root growth from when they went in the pots (after 2 weeks+). Top growth no better, very stunted, have true leaves and look like tomatoes but a third to half the size I would expect at this stage. Main stems thin and weak looking too.

Going to repot half per variety into JI 1 and give the others a good feed, although as this will have to be liquid feed, there is a danger of making the compost too wet and doing more harm.

[Vinlander]

If you repot them straight into JI there's a risk of creating a boundary between the two composts that might let the water stay where it is.

It's safer to remove any compost the (umimpressive) roots haven't got to and mix it with JI to create a intermediate layer between the 0% JI and the 100%.

It also helps to get all 3 layers to similar levels of moisture before bringing them together.

I have also experimented with improving drainage of potted plants by making a hole at the edge about 10% the width of the pot, going all the way from top to bottom (like a taken core sample) and filling it with a mix that's gritty, loamy, and peaty - a soil that I know won't dry out and stay dry. The idea is creating a column that can distribute moisture between levels but mostly sucks moisture out of sodden ones.

It has always seemed to help, though watering from above can be a lot less effective if there isn't a saucer.

Cheers.

[Garden Manager]

I've repotted half the plants now. I carefully removed the old compost and replanted them into the same pots with fresh JI 1 with added vermiculite . As expected root growth was quite poor. I soaked, rather than watered from above, to let them take up the water they need and no more. Always do this with new transplants as it seems better for them. Always drain the pots well afterwards and stand them in gravel trays fitted with capillary matting. Don't water from above until needed.

[Digeroo]

I actually like recycled compost.  I go to the household recycling centre and buy it by te bag full.  Courgettes and beans love it.  Given up on tomatoes they get blight.

[Tiny Clanger]

My tomatoes were slow off the mark this year.  Standard English varieties (Shirley/Moneymaker) were slow to get going.  They are now doing well.  Some other s - Cour di Bue, Marmande, Banana Legs, Green Zebra, Orange Russian, Big Rainbow were also very slow and germination ratio was not good on the Banana legs and Cour di Bue (my favourite).  Some of the plants seemed to take forever to get going this year, but I now have enough to put out.  Due to the transfer and the current cold spell, they have not grown much but have picked up and are going to thrive.

I reckon your toms will be fine - just need a bit more time.  What compost did you use to get them going? Sometimes when all else is good its the growing medium that is holding them back.

[johhnyco15]

here is my later sown tomatoes  sowed in a cold greenhouse 4 weeks ago

[johhnyco15]

some of my earlier sown tomatoes they need potting on again

[Garden Manager]

some of my earlier sown tomatoes they need potting on again

When did you sow them?

[johhnyco15]

some of my earlier sown tomatoes they need potting on again

When did you sow them?

  1st week of march  they have been in a cold greenhouse  1 week after germination really they are ready to put out however ill pot them on and put them out mid may