black plastic sheeting

as some of you know i have cleared an area at the bottom of the garden and placed black plastic sheeting on top. This is preparation for next spring. Now today i decided to pull it back and put more soil in places that were not quite level and i found little seedlings growing under it. I was under the impression that weeds etc would be killed off? shall i just pull them out and recover ? will they eventually die?

 

also there are tree roots in that area will keeping it covered do anything to the tree?

 

How thick is the polythene? I've only used the thickest heavy duty black polythene used as dpm under concrete floor sabs and think a small amount of light still gets through, but any seedlings germinating under it will die and so will established perennials but it takes a bit longer.

If there's a weed seed bank in the soil you can always periodically roll back the polythene to let weed seeds germinate, then re-cover to kill them off.

Personally I'd be wary of covering a very large area under a tree, but putting a shed or impervious paving under one doesn't mean you'll kill/damage the tree.

 

thanks @Scrungee not sure how thick it is. Anyway decided just to put my mind at ease as regards the tree i am going to cut the holes in the plastic ready for raised beds at least then rain can get through and i will only have these areas to weed

 

If you make the raised beds the same width as rolls of Mypex (woven polypropylene, rather than polythene sheet) you can use it to stifle weed growth, reduce the need for watering, permit water (& oxygen) penetration to tree roots, warm the soil underneath, etc., covering them for some crops and removing for others, whatever works best.

 

thankyou