Wickes Multi-Purpose vs Westland John Innes

I've run a little experiment the past month comparing Wickes Multi-Purpose compost against Westland John Innes for tomato seedlings. It's not very scientific and I only did it to see if it's really worth spending three times the amount for John Innes.

The tomato seeds were sown on 4th Feb and pricked out and potted on as usual.

The photos below show the two Wickes M.P. plants on the left, which are etoliated (tall, spindly and lighter green) than the stubbier stronger pair grown in the John Innes on the right.






When I knocked the plants out of their pots the root systems on the two John Innes plants were much stronger.

So the John Innes gives much better results. I'm thinking it's because the John Innes has more nutriments added, but there is no specific information on either product to back that up. Maybe adding a little liquid feed to the Wickes might give the same results.

Going by my results if I was only growing a few seeds this year I would only use John Innes, but as I've got quite a lot to sow I can't afford to use John Innes all the time. So I'm using John Innes for seedlings that need a faster start, and Wickes for the run of the mill bedding plants.

 

I would guess it's would have to do with the ratio and availability of the Nitrogen, Phosphates, and Potash. One compost might be "giving it up" more in balance than the other

 

Krsiten, yes they were all treated equally in terms of light.

Armandii, I think your onto the reason there. I will have to do a bit of further research when I get time.

 

No, just saying the balance of the compost giving up the nutrients could be out of balance. If the compost was giving up less phosphate or potash, or both, it's logical that the plant might end up looking like it's taken up too much nitrogen. I have learnt that not all composts do what they say on the can. Keep your rose tinted glasses on

 

Well, it's obvious that not all composts in the same class perform the same for various reasons, if they did we'd get identical results. It could be that the level and balance of nutrients aren't quite what they say on the bag. Or, that the compost isn't releasing the nutrients in a balanced way even though it has the correct balance.

 

John, thanks for the trial.

Slightly as an aside. We add Osmocote to all our hanging baskets and patio pots when making them up but not when growing seeds or potting up bedding plants. We do add a little when planting out.

 

Bottom watered whilst they were seedlings, then top watered when potted on.


Prompted by the other thread about Wickes compost I double checked my stock, it was last years 75 litre bags even though I bought it recently. Just been over to Wickes in case they still had the older stuff but it's all gone , now they only have 70 litre bags which is more expensive plus the compost is much worse to look at, all twiggy.

Well that's made my experiment a waste of time, I don't have space under my grow lights to start again using this new formula Wickes compost. Personally I'm not going to risk using this new Wickes compost for seed sowing, it looks too poor.