Greenhouse - concrete floor or not?

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10 years 7 months ago #35898 by Del
Kitset greenhouse arrived - yay! Approx 3x4m, and my first. Should I do a concrete pad, or stick with a natural floor? What would you do and why? I understand a concrete floor acts as a heat sink, releasing warmth through the night, but what are the other advantages? Thanks

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10 years 7 months ago #469473 by Stikkibeek
It depends on whether you want to grow in the soil or not. I grow in soil, but have a concrete flagstone path which will give off a little heat after a warm day. By growing in the soil, it commits me to replacing soil about every third year.
Yes you can grow in bags and even use hydroponics, but bags you will have to change every time you replant, and hydroponics are a lot of work to test the nutrient and cost money to run pumps unless you do it the way I do. Bags also take a lot more water and it runs to waste.

What are you planning on using the greenhouse for?

OH built our new greenhouses on a 4x2 frame, all levelled and with 4x4 square posts to support the fame. We were always going to have to build a base as they green houses are on sloping ground. You can of course use hollow stone blocks or bricks as a base, or if you have access to suitable rock, one like Richard has built.

Did you know, that what you thought I said, was not what I meant :S

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10 years 7 months ago #469478 by Del
I'm a novice who's gotten all keen after planting our first garden in January - it's been remarkably successful, so I want to do more! My plan is to grow chillies, capsicums, eggplant, tomatoes, possibly a passionfruit, and to be able to get a longer growing season for herbs, brassicas, dwarf beans, etc. If I did the concrete floor, I'd probably put a raised bed or two in, and I guess some bags, but I'm trying to weigh up if the expense of doing it that way is warranted.

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10 years 7 months ago #469484 by muri
My plant house is a mixture og growing beds and plants in trays that are for sale.
Its rather large and i have mulched much of it, using mulch to raise the beds where the plants in pots are displayed.
It is probably 40+ years old being a market garden over 30 years or so ago and so probably has quite a good build up of disease, mainly mealy bug.
So long term in-ground growing in these conditions could well result in increasingly poor results over the years.
Changing out the soil as Stikki mentions can go a long way to help prevent build up of disease in this kind of situation if you dont want to use systemic sprays to prevent these kind of pests from developing

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10 years 7 months ago #469490 by Stikkibeek
I do utilize our green houses all year round. I plant root crops like beetroot and carrots during the winter, and greens like silverbeet and cauliflower too. In the summer I switch to capsicums, beans, tomatoes and cucumber. I also fit in some cos lettuce which do well all year round, and will be growing these in the hydroponic set up as well as cress and am aiming to try dwarf scarlet beans again. I grew them very successfully one year ans they were just coming into pick-able beans when I got hit with red spider mite. Know what to look out for now.

Did you know, that what you thought I said, was not what I meant :S

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10 years 7 months ago #469496 by RichardW
I dont think you need to as much 'changing out the soil' but take 'some' out and add some compost back in,the soil thats taken out gets added to the compost heap.
Dal- concrete paths work to steady the temps inside the green house,certainly noticed a difference since finishing the beds and pathways in mine recently
File Attachment:

Running superfine Merino's for 15 years drench free and seed grower, sold through www.sentinelsgroup.co.nz/


Inventor of Watson multishears www.watsonmultishears.co.nz

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10 years 7 months ago #469558 by RLD Landscapes
Just to throw in a wild card, you can set up a a hydroponic system as well, so no soil issue there. Soil based is fine, as long as you replenish the soil with good compost and let it lie fallow for a while in-bewteen planting, to recharge it and minimise soil pathogen build-up and "rotate" the crops. No different to an outdoor garden in that respect, just warmer and you can control the atmosphere better, put in some simple dripper irrigation, as its more direct (more efficient) and minimises any fungal spread. I know its only little so why not do a raised bed and hard-stand area, just use old pavers or simply pour a 100mm thick slab. Usually a hard surface is used when the main function is to raise seeds on tables, its just easier to keep critters at bay and clean etc.

phil@rld.co.nz
www.rld.co.nz

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10 years 7 months ago #469582 by Del
Wow that is an awesome path and beds Richard! They must do a great job in temperature stabilisation, not to mention looking fantastic.

Certainly food for thought. I'm leaning towards the concrete floor, as I think the location may lend itself to less than ideal soil conditions - it will go on an area which gets very soft in winter, being predominantly clay with a bit of runoff from a slope behind it.

Stikkibeek, that's a good suggestion re bricks - just thinking that I could possibly use breezeblocks to make raised beds, similar to Richard's but less beautiful :D

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10 years 7 months ago #469663 by Del
Ok, after copious wavering, I've now settled on my (draft) master plan! I'll put down a gravel base, then raised beds from bricks/blocks/concrete, with under surface irrigation lines. I'll put some heavy concrete pavers on the walkway and a little hardstand, where I'll have a wee seeding table and a tap. I'm not ready yet to branch into hydroponics - the whole concept of seeds in the ground is still novel to me! Baby steps :)
Thanks all, feeling more confident now around how to move forward and very excited... Hopefully I'll even get it done by the end of next weekend[?]

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10 years 7 months ago #469671 by RichardW
Good luck Del,love to see some progress photos too.

Running superfine Merino's for 15 years drench free and seed grower, sold through www.sentinelsgroup.co.nz/


Inventor of Watson multishears www.watsonmultishears.co.nz

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10 years 7 months ago #469674 by Hawkspur
The thermal mass of concrete - or any other similar material, works best if it is reasonably isolated from the ground thermally, so the heat mainly travels back into the space rather than down into the ground. You can do this the expensive way, with underfloor insulation, or if your ground is dry, it will be less conductive anyway. Warmth travels through concrete at a rate of about 100mm every 12 hours or so, so if you want to release heat during the night, this is the ideal thickness, because it will take on heat constantly during the day, and release it during the night, but a gravel bed that is on dry ground will have similar effect.
Richards rock walls will nicely release heat into the soil beds and the air, so will benefit both. Is there much ground water there Richard? The central path will give more heat into the air rather than the ground if it isn't on a wet thermally conductive base.
It all looks fantastic.

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10 years 7 months ago #469687 by RichardW
The water table ATM is 1.5m which drops to 5-6m at the driest time of year.
There's also the thermal mass thats held in stone walls that run down each side which you see in my photo,its earthed up on the outside and planted in native grasses to hold the warmth

Running superfine Merino's for 15 years drench free and seed grower, sold through www.sentinelsgroup.co.nz/


Inventor of Watson multishears www.watsonmultishears.co.nz

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10 years 7 months ago #469695 by carlyjean

Del;472176 wrote: I'm not ready yet to branch into hydroponics - the whole concept of seeds in the ground is still novel to me! Baby steps :)
[?]

Those 'baby' steps are steps in the right direction. Food grown by hydroponics can't compete with food grown in a mineral rich and biologically active soil! The nutrient density of veges grown in such soil far outweighs hydroponics.
You should never have to 'replace your soil'. You should strive to improve your soil each year by crop rotation, companion planting and green manures (cover crops)!! (I can't get enough of green manures! They are a great way to add humus to your soil and encourage soil biology!)

So a little tip that I know you'll get great results from: after a heavy cropper (tomatoes/brassica etc) instead of lying fallow- plant a mix of lupin, mustard seed and broad bean. Dig into the soil before flowering. Mustard will cleanse the soil of nasties, lupin and broad beans fix nitrogen, and broad beans also help inhibit fusarium wilt (fungal disease).

Concentrate on growing your soil and your plants will look after themselves!!

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10 years 7 months ago #469697 by kai

carlyjean;472212 wrote: Those 'baby' steps are steps in the right direction. Food grown by hydroponics can't compete with food grown in a mineral rich and biologically active soil! The nutrient density of veges grown in such soil far outweighs hydroponics.

Sorry but that statement is utter rubbish. I would suggest to anyone before ridiculing hydroponics that they study the science behind it.

I would like another small scale hydroponic set up here (compared to my previous commercial scale set up). My only reason for not doing already is that I have yet to find a suitable solar pump to power it.

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10 years 7 months ago #469699 by carlyjean
Sorry this was not 'ridiculing' hydroponics- it's merely a different view. I have been trained in organics and BioDynamics (a huge worldwide industry), and the science behind these growing practices is massive (and they don't allow hydroponics).
I hope this doesn't turn into an argument- I just wanted to get a different perspective across. This forum is about discussion, not ridiculing and I apologise if my comments came across that way!

I found this excerpt from the organic pathways
website that sums it up nicely:

"The soil is the foundation for plant and animal and human health. The soil acts as a buffer for any drastic changes, such as incoming diseases or insect pests etc. A hydroponic system is highly vulnerable and is lacking the stabilising effect of a real, living soil, even if it may use comfrey and nettle teas for fertiliser solutions."

I realise this thread is not about organics but it is about growing and this highlights the importance of healthy soil. For the home gardener I believe you can't beat growing in real biologically active soil!

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