Why is nothing growing with composted bark mulch?

[keebo]

Just what the tutor says really. We put a mulch of partially composted bark on 2 of our veg beds which had horrific weeds last year and not a single plant is growing in it. We've tried all sorts, squash, borage, courgette, onions, kale, beetroot, lettuce... The plants don't die, they just don't grow. The squash, courgette and borage are exactly the same size as when I transferred them for pots. Meanwhile, the non-mulched beds are doing really well. Has anyone else had this? Any ideas? Do I need to get the mulch back off before next year?

from what kind of tree?

some trees produce weed suppressing things that stop seedlings of other plants to grow.

and how long ago did you plant out?

heat supresses growth as well as cold.

weeds growing is generally a good sign that all is well with the soil.

Was it truly composted? Did you buy it such or were they chips provided by a tree surgeon? Decomposing bark takes a lot of nitrogen out of the soil.

I can't remember which company it was, but we bought it in bags from the local garden centre. It was sold as 'ideal mulch for borders and veg beds'. It clearly isn't!

The squash, courgette & borage were planted out after the last frost in April, then I did another set in may so they've had both a bit of cold weather and warmer. Still no growth. Everything else went in May, the same time as the rest of the beds which are doing perfectly well.

does it look like there is a lot of conifer in it?

@keebo Partly composted bark mulch robs the soil of nitrogen as it decomposes. So I suspect that is what's happening here.

Maybe giving the plants a feed high in nitrogen would help things along.

Thanks! I'll try this over the weekend in the hope we can still have some squash for the autumn. Finger crossed!

In case anyone's interested, thank you for your replies! We added fertiliser (organic chicken poo pellets with high nitrogen levels) at the weekend and plants are already growing better!
Lesson learnt - welcome the weeds and avoid composted bark as a mulch.