Topic: using grow bags

[kimbobill]

I wondered if the compost in grow bags was ok to bring on young seedling next spring, It just that they are 99p for a 35l bag much cheaper than the 50 and 75l bags of compost at 3 to 5 pounds ago?

[laurieuk]

If you are thinking of re using the compost from a crop this year the answer would be no, if you are thinking of buying new grow bags to use as seed compost you might find the food level could be too high for seedlings and the roots would get burnt. You could waste more money on lost seedlings than buying the correct compost.

[chriscross1966]

THey'll be OK for bigger things, especially hungry stuff like squashes and sweetcorn, once they've got to the 5" pot stage... most of my stuff like that goes through three stages, module, 3" then 5"... soemthings like squash basically start in a 3". I use shop-bought MP for sowing, council-made compost+topsoil for transplanting.... council stuff round our way is about 30 quid a ton, and a ton is about 3000 litres.... The compost is a bit coarse, too much so for seed sowing, but the mix with topsoil makes an excellently structured potting medium, I just add some BFB for those things that need it (beans don't for instance)... I guess that price isn't too bad if you have no transport that can handle loose compost (I have a van and a trailer, I can collect nearly a ton at a time if I fill them)

chrisc

[goodlife]

Re-using compost is always safest for something more established or just as 'soil conditioner'. Saying that..I do grow lot of salad stuff in containers and I tend to use  'old' compost in bottom of the containers..mixing little Blood Fish and Bone meal with it to give some nutrients back and fill rest of the container with 'fresh' compost and sowing seeds on that..

[kimbobill]

These are new bags, a good make (can't remember ) it is from a shop that deals with bankrupt stock.

[goodlife]

Ahh...I see..well it depends what you are going to grow on them....generally you can sow more and less any veg straight on it..but those that are planted as individual plants, like cucumber and tomatoes are better sown and grown in smaller containers and then planted into grow bags. But things like salads..straight on..those kind of things that you would sow on ground and thin out later on.
What you were thinking of growing?

[Vinlander]

I have had no problems using fresh growbag compost for seedlings in spring when the quicker the growth the better BUT I've never used it in autumn... so it's possible that the seedlings might grow too fast and soft to survive over winter.

I've had no problem reusing growbag compost either though I add some fertiliser like everyone else.

Gardening Which did a test last month and came to the same conclusion.

However after several years of use some composts lose their structure and can become almost as claggy as clay - that's the point to mix them with coarse grit or perlite - or use them as mulch on soil.

Cheers.

[kimbobill]

Thank you for the replies. I have brought some that I am going to plant out with salad crop under 2 shower enclosures that I got off of ebay for 99p each I am going to raise them up and can control the heat with the twin sliding doors along with a water supply from a pump run of a solar panel well that's the theory, I'll let you know if it works.

I was wondering if it was OK or too rich for pricking out, after seeds have been in john innes no 1. mainly broccoli and it's family plus leeks

[Melbourne12]

I wondered if the compost in grow bags was ok to bring on young seedling next spring, It just that they are 99p for a 35l bag much cheaper than the 50 and 75l bags of compost at 3 to 5 pounds ago?

We regularly do this, and have had no problems.

[Tee Gee]

I agree with Laurie........ however!

You could thin it down with river sand and this will dilute the 'fertiliser' content (by ratio)

This is  how I do it; http://www.thegardenersalmanac.co.uk/Data/Compost/Compost.htm  click on pictures to enlarge.

Subject to the content of the growbags you may or may not require to seive it!

This method gives the best of both worlds i.e. you have a seed and potting compost at your disposal.

An example could be; halve the content of the bag and mix in river sand at a ratio of two compost to one sand.

This will give you a good seed compost with just a hint of fertiliser. Once germinted prick out your seedlings into the other half.

If you have bought two or more bags I would have thought you would have sufficient seed compost for your needs by using a half bag and the other one and a half can be used as potting compost!

Best of luck!

[kimbobill]

Thanks Melbourne12 and Tee Gee,
River sand, do the say on the bags of sand, river sand? or is is it best to taste it? and is it soft or sharp sand?

[Tee Gee]

River sand, do the say on the bags of sand, river sand? or is is it best to taste it? and is it soft or sharp sand?

The one you want is 'Sharp sand' the one for making concrete not the type for laying bricks!

If I am in places such as B&Q I go to the 'building' section rather than the 'gardening' section for it!

It is always dearer in the latter.

OK it might be 'washed' but to be honest I have never had any problem with the concrete making stuff so why pay more for something that has been supposedly 'washed!

Another type I quite like for seed sowing is; 'kiln dried' sand, it has the same texture as silver sand which again is quite expensive in the 'gardening' section.

Silver sand makes for a much finer seed compost, particularly if you have sieved the compost!

This type (silver sand/seived compost) is also better at the pricking out stage! i.e. the seedlings don't have lumps of roots sticking to them when you prick them out!

[Morris]

That's a good idea, Tee Gee, the builder's sand, thanks.  I do exactly the same, buy multipurpose or growbags mix it up myself with sand to get the type of compost I require for each stage.

[lincsyokel2]

That's a good idea, Tee Gee, the builder's sand, thanks.  I do exactly the same, buy multipurpose or growbags mix it up myself with sand to get the type of compost I require for each stage.

I really really really wouldn't recommend you use growbags like this. A growbag is basically the factory floor sweepings, mixed in with some used mushroom compost and dosed up with a 14-10-14 general purpose fertiliser. The best use of used growbags is either as organic material dug int as a soil improver, or mixed into the compost heap to  provide brown stuff.

If you want seed compost, the cheapest way is to make your own is

John Innes seed compost: In the following loam is sterilized and peat and loam are passed through 9mm sieve.

2 parts loam, 1 part peat, 1 part sharp sand
0.6kg ground limestone (you can use  garden lime) , 1.2kg superphosphate per 1 cubic metre of mix.

if you'r near Lincolnshire ill give you a couple of 25 kg bags of Superphosphate free