Raised garden - how to use topsoil.

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rayonline

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#223557 5-Oct-2017 20:18

Hi all

We live in an area where the ground is quite granite and have struggled in many years. We built a raised garden along the fence. Mitre 10 suggesetd we go to a landscape place and get topsoil by the bulldozer since the $14 14 liter bags of Garden Mix would be quite expensive. So we layer the topsoil and with compost on top or do we mix it together? The guy at the landscape said mixing, just wanna double check.

Currently there is nothing there, no existing soil.

Cheers.

Stu1

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#1878119 5-Oct-2017 20:41

We just mixed it in after topsoil compost and sheep pellets worked well, we dig in more goodness every spring. I thought most mitre ten sold top soil out the back by buckets

timmmay

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#1878126 5-Oct-2017 20:57

I'd consider putting down a plastic groundsheet if you don't want anything in the soil to come up, or your soil to run away.

90% soil, maybe 10% compost. Chuck it in and grow things. It's not rocket science.

In Wellington I find a greenhouse really useful. I had it built after two years trying to grow things outside and having them killed by the wind.

t0ny

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#1878203 5-Oct-2017 22:49

Bunnings sells this thing which is like peat for 3 bucks a bag. I mixed that with the garden mix to get the volume up. Has worked out really well.

KiwiTim

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#1878281 6-Oct-2017 08:48

My father did what your doing. He got a truck load of topsoil delivered. I would spread the topsoil in your raised garden, then spread compost or animal manure over the top and dig it in. From the plants perspective most of the action will be in the top 20-30 cm, so this is where you want the organic matter mixed. Digging it deeper down will be less useful. Soil microorganisms constantly break down organic matter and ultimately it is converted to CO2 and floats away, so you need to constantly add more. If this is a vege garden or flower bed I'd add compost 2-3 times a year over the whole area. If this is shrub border, then I'd just mix the compost in the spots where you are going to plant the shrubs. In the case of trees and shrubs you could mix the compost down deeper than 20-30 cm, perhaps 45 cm. I would not advise putting a plastic sheet between the ground and your raised garden, as the plastic will prevent drainage, and the soil immediately above it will become saturated and oxygen deprived. Most plant roots do not willingly grow into anoxic soil. If you wish to prevent growth of weeds coming up from the ground below overlapping old cardboard boxes or weed matting will do that and still permit the passage of water. If this is a vegetable garden you should add lime to raise the pH. Organic matter increases soil acidity. If it was say a native shrub border, then I would not bother with the lime, as most native shrubs are quite happy in more acidic soil conditions.

Coil

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#1878283 6-Oct-2017 08:52

Go hire a trailer and drive around some back roads in your area and nab some volcanic soil from a cut away! Find someone selling or giving away horse poop and mix it all together, maybe some other composts too. Volcanics is great as it drains very well and is full of nutrients. Your typical brown topsoil has nothing on the ol volcanic.

*Grew up on a organic farm with volcanic topsoil.

Jase2985

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#1878378 6-Oct-2017 11:00

the likes of central landscaping do a specific garden mix soil. comes premixed with compost in it.

just buy it by the trailer load and be done with it :)

rayonline

1734 posts

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#1878463 6-Oct-2017 13:15

Yes they have the garden mix with everything in it. We bought the compost already, the others thought they didn't need the topsoil.

We got the topsoil, some compost for the top and lime and using cardboard for the bottom, got some clay breaker too, blood and bone and sheep pellets. Yes mainly vegetables.

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rayonline

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#1878780 7-Oct-2017 08:17

Read tui online as in tui garden products. They said compost needs to be digged in 20cm deep and wait 1 or 2 weeks since it burns the plants or else use garden mix. Your view?

MikeB4

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#1878794 7-Oct-2017 08:33

We never use top soil in raised beds it is too prone to clumping and turning to mud. We use pre prepared mixes and add our own compost and sheep pellets. We let the beds rest over winter then start early spring by aerating the soil, topping up the mix and slowly adding and digging in compost. It’s important to turn the bed at least weekly before planting. After planting ensure soil continues to be aerated. Water at least 2-3 times to week, don’t do small watering as this promotes fungal growth. Wet the bed thoroughly then leave it, water when it feels dryer a few inches under the surface.

KiwiTim

376 posts

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#1878810 7-Oct-2017 09:07

rayonline: Read tui online as in tui garden products. They said compost needs to be digged in 20cm deep and wait 1 or 2 weeks since it burns the plants or else use garden mix. Your view?

Fresh animal manures and compost can burn the roots of tender young plants, but having said that many years ago I worked at the Wellington Botanic Gardens. When planting the big flower beds we would dig in new compost, spread lime and fertilizer on the top, lightly rake in the latter, and then plant. The time span between digging in the compost and planting was 1-3 days and I never saw any ill effects.

I think fresh chicken manure can burn, but compost, if well broken down, is probably ok to use the same day as planting. What I do in my own vege patch is make sure the compost does not contact directly the newly planted seedlings; just make sure there is a handful of soil between their roots and the nearest clump of compost.

Have fun. Get yourself a Yates Garden Guide as that publication is an excellent guide for new gardeners.