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Growing media for veggie containers
in Fruit & veg
Hi all,
This will be my second year with a garden and so I'm still new to all this. I'm trying to research what an ideal general growing medium would be for growing veggies in a large container (old trough, drainage drilled in the bottom), but I'm finding it quite a headache. There are a lot of "recipes" and opinions, many call for homemade compost which I don't have right now (and not sure I will do in the future because of the small space), and when it doesn't it seems that the type of "compost" required is left unspecified. When I mosey on down to the garden centre I'm then faced with an array of different compost bags and always feel like I have no idea what I'm doing (which I don't... it's why I'm here!).
Last year I filled the trough with a standard peat-free multi-purpose compost (Dobbies own) mixed with some of our own garden soil, probably about 60:40 respectively (that's as much soil as I had spare). I grew 2 yellow courgette plants, mulched with a thick layer of bark. One grew wonderfully, the other not so well. Not sure why but I don't think it was due to the soil mix.
Can anyone give me some advice on what I need to do now? Do I need to replace the growing medium in there completely with something else, or can I just add to it? In either case, what soil/compost/amendment/fertiliser should I be adding (and ideally I'd like to know why so I can understand better), and when should I be doing it throughout the year?
I realise this will depend a lot on what I intend to grow in there, but I'm guessing that amendments for specific plants would work off a similar base, so for me understanding the general starting point is really important.
Thanks so much, kind garden people.
Nick
This will be my second year with a garden and so I'm still new to all this. I'm trying to research what an ideal general growing medium would be for growing veggies in a large container (old trough, drainage drilled in the bottom), but I'm finding it quite a headache. There are a lot of "recipes" and opinions, many call for homemade compost which I don't have right now (and not sure I will do in the future because of the small space), and when it doesn't it seems that the type of "compost" required is left unspecified. When I mosey on down to the garden centre I'm then faced with an array of different compost bags and always feel like I have no idea what I'm doing (which I don't... it's why I'm here!).
Last year I filled the trough with a standard peat-free multi-purpose compost (Dobbies own) mixed with some of our own garden soil, probably about 60:40 respectively (that's as much soil as I had spare). I grew 2 yellow courgette plants, mulched with a thick layer of bark. One grew wonderfully, the other not so well. Not sure why but I don't think it was due to the soil mix.
Can anyone give me some advice on what I need to do now? Do I need to replace the growing medium in there completely with something else, or can I just add to it? In either case, what soil/compost/amendment/fertiliser should I be adding (and ideally I'd like to know why so I can understand better), and when should I be doing it throughout the year?
I realise this will depend a lot on what I intend to grow in there, but I'm guessing that amendments for specific plants would work off a similar base, so for me understanding the general starting point is really important.
Thanks so much, kind garden people.
Nick
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What are the dimensions of the trough? Troughs tend to be shallow, which will also have an effect on what you grow. It can be very confusing re the different composts etc, so what you grow is the main factor. You can re use what you had by adding a general fertiliser and some fresh compost, but things like carrots don't like over rich soil. Some veg also benefits from being grown in a different site from previous years to prevent possible diseases, so if you have an idea of what you intend growing, that will help with advice
Generally - a soil based compost holds water better in a container than compost alone, so if you have clay soil, that will have held the water better than a light, sandy soil. That's more important for long term planting though - shrubs etc, rather than veg. Drainage is important, regardless of what you grow, but your climate and rainfall are factors too. You may have to water more if you're in a very dry area and you're growing veg that needs lots of moisture.
I live in west central Scotland - not where that photo is...
I think loam based composts are best for most fruit and veg especially hungry ones like courgettes so buy one that says it's a John Innes loam-based formula 3 or is specially formulated for fruit and veg. Be prepared to add nutrients thru the growing season either with pelleted manure; blood, fish and bone or seaweed. These have balanced NPK levels and seaweed has extra minerals. Google NPK if you odn't know what it means.
You can also use liquid tomato feed as a tonic when watering things like tomatoes, chillies, courgettes and squash as it has higher levels of P and K which are needed for flower and fruit production. For cabbages and salads, get one high in nitrogen for leafy vegetables. Brassicas also appreciate some extra lime or calcium as that helps keep them healthy and ward off club root.
Fairygirl, the trough is 125L x 45W x 40H (cm), so not as shallow as they can be sometimes. As you mentioned, I'm intending to start rotating crops around. I haven't got too many planting areas ready just yet to have a 3 or 4 year rotation plan so for the moment I was thinking of moving a couple of indeterminate tomatoes into the trough. Last year they were in my border close to a fence but with a lot of sun and did very well. Incidentally, the soil I mixed in the trough came from that border! My feeling is that mixing this in helped structurally (but not sure about nutrition) and with water retention. It is a loamy type of soil.
By general fertiliser do you mean something like Growmore or blood, fish and bone, as Obelixx mentioned? Are there any others that you'd recommend? What about things like manure pellets, worm castings, slow-release (6 month) fertilisers etc. I'm curious to know what you think about this and the compost (e.g. loam-based or soilless) with the added info. Either way I unfortunately won't be growing carrots ever because my wife has a genuine phobia of them
Obelixx, you would recommend starting afresh. Hypothetically, if I did make my own compost, would the situation be better, in the sense that would adding this to a container help replenish the old soil, similar to how digging in compost or laying it on top of the borders or raised beds after the growing season would be sufficient in that planting format? I have to say that the prospect of replacing the soil every year is kind of painful. I enjoy the rewards of growing my own veg but it hurts if it isn't economical. Noted about using it as a mulch in the borders, that's a good tip - I guess the follow on question is, if the nutrients are so low in the used compost then how would it help as a soil improver?
I'm aware of the NPK notation and have a basic understanding of the relationship between each of the elements and plant growth; a related headache to the compost issue though is which fertilisers are generally best to use, how much, when etc. Is it OK to double up, for example, adding fish blood and bone around tomato plants and then at some point in the season start watering with Tomorite as well? If I lay a thick layer of bagged compost as a mulch would that be sufficient feed as a "slow-drip" or would additional fertiliser be necessary on top of that? I'm perhaps overly cautious about over-feeding... Google often makes things more confusing as you start finding things like comfrey and worm tea...
In the mean time I've seen some advice for mixing good topsoil, compost (not sure which) and organic matter in a 50:30:20 ratio as a good starter for container edibles. I've also had some advice last year that I shouldn't use topsoil at all. What do either of you think?
I forgot to say that I'm situated in the Southeast, UK, in case that helps with any thoughts on our weather!
Thanks a lot both!
Nick
(a)'garden compost' i.e. the compost you make in your garden compost bin from grass, plant trimmings, shredded paper etc etc etc, and
(b) 'potting compost' i.e. the bagged multipurpose type compost or loambased John Innes growing composts, 1,2 and 3.
In order to make your own 'potting compost' you use garden compost, loam, grit and/or other materials in varying proportions.
Otherwise (a) garden compost is best used as a mulch or soil improver.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
3 parts loam, 1 part rotted manure, 1 part sand, 1 part leaf
mold I got this from one of my old ww2 garden magazines
they sifted it to remove large chunks.
If your existing planting medium in your troughs already has a good rato of soil in its mix then adding a fresh mulch of well-rotted manure will feed it, well-rotted garden compost will improve it but provide less nutrition and adding a mulch of good quality commercial compost for planting will also help but be a bit more pricey.
Using spent compost from tubs and troughs as a mulch improves soil texture but you'd need to add a suitable fertiliser for the crop you intend to plant afterwards.
We add a layer of our own garden compost to any veg bed before planting up and then I scatter pelleted chicken manure as needed. The tomato and chilli beds get double rations and extra tomato feed later in the season.