Topic: Growbags v MP Compost

[bluecar]

Hello all.

Does anyone know the difference between the make up of growbags and multipurpose compost?

Is there any reason why growbags seem preferred to mp compost for tomatoes?

Regards

Bluecar

[Obelixx]

You'd have to read the info for the composition but Growbags usually have fertiliser rations and levels designed for growing veg.

Personally, I think MP compost is only fit for use as a mulch to imrpiove soil structure over the winter or, sometimes,mixed in with a John Innes no 3 to improve water retention in a pot.

[saddad]

As Obelixx says some growbags have more fertiliser in from the start. MP is only good for about 4-6 weeks before it will need regular feeding.

[ancellsfarmer]

This is what Westland declare for their growbag product.
http://www.gardenhealth.com/product/growbag
With tomatoes in mind they mention high potash.
Doubtless the nutrition is a composted manure of some species. No information is provided. Make your own guess as to which species is most numerous.

[George the Pigman]

That's what I understood that the growbags have added high potash fertiliser. However one problem I have had is that they are often soaking in water when opened which can lead to rot with cucumbers in particular.
Good quality multipurpose is fine but you need to add more fertiliser as the plant grows. However I have found there is a lot of rubbish multipurpose compost around nowadays - often with "recognised" brand names. Currently I use by Jacks Magic and find it fine.

[bluecar]

Thanks all. I guess I could try MP with added potash, but I'n not sure it's worth the effort.

[Vinlander]

Because growbags are designed for planting potted seedlings (like they are sold, at 25+cm tall) they don't have to be as finely sieved as MPC. Obviously any bagged medium varies enormously from one manufacturer to another, and price is NO GUARANTEE of quality in any area, especially ones like fineness when they aren't relevant.

If I hear that saw "you get what you pay for" again I'll go ballistic - it's nonsense logic - we've all paid top dollar for things that turned out to be $#!+... The saying that works is "no such thing as a free lunch" it's true, and the shopping version is "you don't get what you DON'T  pay for". The other one that's true is that "free" stuff often costs you more than stuff you pay for (but not always).

Growbags have enough fertiliser to "wake up" middle sized greedy plants, but they still need extra feed by mid-season.

MPC should have medium levels of fertiliser for medium plants with medium greed, but not enough to "burn" tiny seedlings as soon as they emerge. The safest way to fit this need is with highish levels of well-aged complex natural fertilisers - but these are expensive.

Cheers.