Compost - ditch it all, or only some?

I don't have big 150L containers ... so not sure how I would deal with those if I had them.

I treat my "spent container (MPC) compost" the same as the veg patch - I pay due regard to crop rotation.

Multi purpose will have enough nutrients for the first few weeks only, so you've got to feed it anyway during the season. Spent MPC just needs feeding from day one - I favour the slow release "hundreds and thousands" because my feeding regime generally is "when I remember".

So ... here spent compost from Tomatoes is not reused from Tomatoes, Potatoes etc. Putting it on some shrubs is an obvious answer, but I don't think they particularly benefit from it, unless you are using it instead of another material for a (deep) mulch in the spring. This aint a "few handfuls" incorporated into the soil around the plant, but rather 3" or 4" in a circle around the plant to preserve moisture etc..

My preference is to use spent MPC for container planting of ornamentals (mixed with rotted manure and something soil-based to make it easier to re-hydrate dried-out containers), or to mix it 50:50 with sharp sand to grow carrots in (in containers). I also use it to bulk up the mix for things that are grown in large pots (whether they stay in them, or get planted out) - for example Bananas that I am planning to bring in for "one more winter" before they get planted out.

I don't put it on the compost heap as it gets mixed in with everything else, and then redistributed back on to "same crop". (I do compost the culms from Tomatoes / Spuds, if healthy, and some of that compost obviously goes back on Tomatoes / Spuds, but I don't have separate compost heaps for crop rotation whereas it is relatively easy to segregate bags of spent MPC)

That leaves the issue of bugs ... if anything is diseased or there are obvious bugs in the soil (eggs usually are slugs ...) I chuck it on the shrubs. However, you might not be aware of the bugs until next season ... that's what crop rotation is intended to help avoid, 'coz you don't replace the soil in your veg patch every season, of course

For "permanent container growing" I favour having a soil + MPC mix (with manure, home made compost, etc.) and then just treating it as crop-rotation. However, that's for decent sized raised bed type containers ... not sure how that translates to "containers" as small as 150L ... could your 150L containers become something more substantial? wooden framed for example? If you go down that route you want something soil-based - easier to water - but with plenty of humus in it - spent MPC or rotted manure will do for that.

By the by, if you are mono-cropping from [largely] same-soil then worth considering grafted Tomatoes (and probably other crops too).

And, just to sit more firmly on the fence!!, I change the "soil" in my greenhouse every year. This isn't strictly necessary (every 3rd year is the normal recommendation for greenhouse mono-cropping borders), but I use 50:50 home made compost and rotted manure; its very coarse (I don't faff about getting it well and truly composted, or sieving out the "Big bits"), and after a year in the greenhouse its perfect! that then becomes the basis of my "planting soil" when I dig a hole to plant something in the ornamental in my "only-good-for-making-bricks" clay soil. So that's a possible alternative destination for spent MPC - improving the soil in a planting hole.

I think I would avoid mixing old-and-new - you will keep any existing bugs so you might as well stick with old, or replace entirely with new. The feeding issue remains (but, as I said, you will have to feed anyway; only other observation on that is that crop rotation is, in part, designed to vary the feeders - so successive crops make different demands on the micro-nutrients, and give the soil a chance to rest, so crop rotation in containers will help. Also watch out for "unbalanced" fertilizers - Miracle Grow has NO Magnesium, for example ... so at the least perhaps alternate brands - perhaps have a look at Chempak as the alternative.)

You absolutely must get a compost bit. They definitely don't smell but put it somewhere discrete so you can pee on it each day - that will dramatically speed up the composting process, and save a loo-flush. Its only a couple of feet square. Yes you won't make much, but it saves carting all your garden waste to the dump/recycle and then returning it to you in bagged form (yeah, the bag you buy won't be your original material, but same difference ...). Otherwise I'll have to get Zigs to make a new "Coventry" forum ... and send you there!

OK, typed far too much already ... I'm outta here now!

 

Have you got enough bags / does it "work out" that you can do some sort of crop rotation between the bags? If so I would do that, and skip the "replace the compost" step Always provided that there is no disease, and in the Spring you don't find evidence of a termite-dom's population of unwanted creatures!

 

There was a thread recently (I think on this forum!!) saying that recommendation was to use 30% or maybe 50% sand with MPC for "containers", so that might be a good route to try?

 

Well I mix new with old compost in my containers plus hundreds and thousands fertiliser , BFB and sharp sand . For my baskets I use shiney new compost. I distribute my old compost onto the flower beds. Seems to work for me .
Oh and FC , if you want some info on MPC wait until late Feb , you can't believe the wealth of information you get when that thread starts - 300 posts minimum

 

Blood, Fish & Bone - organic (well, provided the blood came from animals that were themselves organically reared - i.e. unlikely!) fertilizer