raised bed question

Hi, I am building my first raised bed for veg this week and I don't know wether it is a good thing to lay some builders membrane in the bottom, it will allow drainage and stop weeds and some pests but will it stop good root developement, my boards are 300mm high. any help appreciated.

 

Hi Blacksmith,

Depends what you are planning on growing, a foot is fine for most things, but if you are going down the Parsnip road then no.

 

Hi Ziggy, I could bury the membrane say about 200mm first and place the bed over it, Ican still bring the material up the sides.

 

Not sure it necessary unless you've got bindweed, couch grass, creeping thistle and so on.

Most of the annual weeds will be germinating in the top bit anyway & most veg roots dont go down that far.

Thing i'd be more concerned about is water loss with a raised bed, they are difficult to keep wet enough, so i'd be digging in as much organic stuff as possible and also some broken clay flower pots or moisture retaining granules.

 

I made three raised beds on the allotment this year mainly for carrots and parsnips . I don't have many perennials weeds so didn't use membraine .As Ziggy says water is a problem and although I now have some great carrots and parsnips it was a struggle early in the season to keep them moist for germination and whilst they were small. However for me it as been a success.
Dave

 

I am very fortunate in as much as I have an unlimited supply of mushroom compost which was based on horse manure, fresh horse manure, and I have purchased 1 ton of graded top soil (a nice medium loam that clings when compressed), I also have some leaf mulch and saw dust, can you suggest the mix ratio for the best result please.

 

Hi Dave,thanks for the reply, glad to haer your beds were successful, very incourageing, I am thinking that the membrane might stop slugs as I ahve read a lot about beds and organic gardens in preparation for my own attemps and on ething that crops up a lot is slug problems, my thinking is that they must come up the iniside of the beds so membrane will make a barrier. However this is only my theory as I have no previous experience.

 

No, we need Kristen for that sort of detail & unfortunatly he's not been around for a bit.

Mushroom compost good, pile the fresh horse poo up to rot down for 6 weeks, leaf mold is good for water retention and soil conditioner, sawdust robs nitrogen as it rots so either add more in the way of dilute urine or rot it down with some chicken poo first before adding to the bed.

Are you sure the sawdust is not from treated timber ?

 

Again I am fairly lucky as there are very few slugs on my plot ,not sure why..not lost anything due to slugs ...Agreed with Ziggy be careful with the sawdust .
Dave

 

the saw dust is ok, I have cut up 40 ton bags of firewood since last November and have added it to a wormery with horse poo and the worms must think it is viagra because we have a population boom.I can also get stable cleanings with more straw if this helps with water retension

 

Thats great then Again, straw needs nitrogen to rot down, but with horse wee wee with it it should be fine

 

Thanks for your replies guys.