Topic: Changing soil in raised beds? Falling yield of courgettes.

[gray1720]

A friend has asked the following - not growing mine in raised beds, hopefully someone here will know. She's a bit further north than most of us here - in Gothenburg, similar latitude to Barra in the Hebrides:

She grows courgettes in raised beds and each autumn adds mulch from the compost bin, then digs it in when everything thaws, usually around March, but the yield falls off each year.

Should she change to completely fresh soil?

Thanks!

Adrian

[ACE]

If you had a part of your allotment that when a bit barren you would not move all the soil, you would enrich it, The same goes for a raised bed surely. I would ask what damage is done to the mulch they put on then lets it freeze, I would dig it in not lay it on top. My raised beds are feed with chicken pellets as I am planting, then a few more later to encourage the crop. Also growing the same thing year after year will not help, perhaps a crop of field beans to dig in one year.

[Obelixx]

Agree.  Enrich and improve the soil with nourishing well-rotted manure.  Compost improves texture but isn't, in itself, filled with nutrients unless it's got lots of comfrey in it.

[ancellsfarmer]

"A friend has asked the following - not growing mine in raised beds, hopefully someone here will know. She's a bit further north than most of us here - in Gothenburg, similar latitude to Barra in the Hebrides:

She grows courgettes in raised beds and each autumn adds mulch from the compost bin, then digs it in when everything thaws, usually around March, but the yield falls off each year.

Should she change to completely fresh soil?"

Not in my opinion.
Feed the soil, not the plant. It contains billions of friendly organisms. Stop dosing it with poisons. Stop tipping them all into deep trenches, where they are less likely to thrive.


I think its time you introduced her to Richard Perkins. He is up in Sweden and should build confidence in your friend..
www.youtube.com/watch?v=EuN_kbQ1oaA

[BarriedaleNick]

No - just feed the soil.  I suspect her mulch is pretty low in nutrients as a whole or some specific one in particular which is diminishing returns.
Chicken pellets are a good quick fix but well rotted farm manure is the better option in the long run.  At least some sort of organic based feed can be used to perk up plants - I make a chicken poo tea for certain greedy plants which seems to help.

[plotstoeat]

I grow my courgettes in the compost I made in the previous year by taking all last year's compost out and replacing it with the new compost. I then cover it with black plastic and plant through it. I feed with Tomorite mainly but also some seaweed. This method has always been successful. I also grow some in containers which is okay but the season is shorter than the ones grown in the compost bin.

[galina]

It is awfully far north for courgettes, which may be a factor.  Maybe they need a good year as well as good soil to thrive.  And the actual temperatures and sunshine hours may matter as much as the soil. 

However,  we do not know the ph of the soil and it could matter, the variety of courgette or the actual weather.  Does Gothenburg generally grow courgettes or are they really difficult and marginal.  If they are a marginal crop that far north, then maybe planting through black plastic on top of the mulch would help, because it warms up the soil.  Like plotstoeat suggested.  As of course would a cloche cover in the early days before the plants are fully established.

The good initial year might have been a weather fluke and the decreasing yield may be due to factors outside of the soil. 

I would measure the ph value just to make sure that it is not way off, then I would add soil warming (black plastic) and protection (cloches).

Not knowing the growing conditions in Gothenburg, it would help to know whether all gardeners find courgettes difficult, because they are right at the very edge of what can be grown, or whether courgettes grow quite well and it is only your friend who somehow has a problem that others do not have. 

I remember a gardener from Orkney on this forum many years ago, who could not grow courgettes even with hand pollination in a greenhouse.   It sounds to me like there might be a geographical challenge as well as a soil challenge. 

[saddad]

I remember living 800' up in the Pennines in the 1970's it was (almost) impossible to grow courgettes at all... I think newer varieties have been developed to be more cold tolerant and possibly less light dependent... as Galina suggests your friend may just have got lucky that first year.. as I did in '76....