Just filled this raised bed with some veggie mix I bought from my local nursery. According to them it’s equal parts mushroom compost and top soil. I’m seeing really poor drainage so far. This picture was taken after maybe 45 seconds of water from the hose. Any recommendations or amendments i need to make to improve this? I added a huge bag of perlite today but it’s still not draining very well.
by Global-View7706
21 Comments
How hard is your dirt underneath the bed? If it wasn’t filled up it may be compacted and not drain well.
Perlite is best for aeration and drainage, while vermiculite excels at moisture retention and nutrient availability.
Add vermiculite
also people like this mixture ===mels mix
[Mel’s Mix Resources](https://squarefootgardening.org/mels-mix-resources/)
I went the 25 percent ,compost, peatmoss, vermiculite, perlite, but I tend to go a little heaver with the compost, this will be my 3 year with raised beds, last year i just added compost to bring the level up after the winter.
I have the same type of raised garden bed and instructions are to fill almost half with wood, a layer of green matter, then compost and soil. I believe it is recommended to help with drainage that will eventually decompose.
soil can be too dry making it hydrophobic.
as a result the water stays on the surface without soaking in. When you say it is not draining do you mean that it is not penitrating the ground layer, or it is not penetrating through the soil you added?
What is that black material under the bed?
Do you have cardboard and weed barrier under the entire raised bed? If so odds are that’s a place to start.
is that ply wood poking out of the bottom right corner of photos 1 and 2?
Soil is probably hydrophobic and that’s why it’s pooling at the top
Does it have drainage holes??
How long did that take to drain away? How wet was the soil before you added water?
To prevent the soil from becoming hydrophobic, the best thing to do when filling up a raised bed is adding soil in layers and watering it. This will help to prevent what you are experiencing.
It’s strange. Next time I would get normal compost which always has bits of wood and other stuff for drainage and also add perlite like you did. Normally beds like this drain easier so something must be in the old compost that is hydrophobic.
Weed barrier will stop the worms, use cardboard which will kill the grass/weeds but then break down into worm food.
Most likely the soil was too dry to start with a couple of days of rain and it will be fine
How well did you mix it before you put it in there?
That mix looks pretty heavy.
Equal parts mushroom compost and topsoil can end up acting more like regular yard soil than raised bed mix… especially if there’s clay in it. Raised beds usually drain well because the mix is lighter and has more structure.
If it’s pooling after 45 seconds that tells me it’s prob too fine and compacted. Perlite helps, but one bag usually isn’t enough if the base mix is dense.
I’d work in something chunkier. Pine bark fines are great. Even some coarse compost that isn’t super screened. You want it to feel loose in your hand. If you squeeze it, it should fall apart, not stay in a sticky ball.
Also what’s under the bed? Fabric or hard packed soil underneath can slow drainage more than people realize.
Sometimes fresh compost mixes just look bad at first because they’re saturated. After a few dry cycles they can improve a lot.
Worst case I’d pull some of it out and lighten it up with a proper raised bed blend.
if you have a weed barrier underneath the bed that is definitely going to prevent proper drainage
Drill holes through your underlayment into the ground.
Drill weep holes 1″ up on the bottom of your beds (¹/⁴to ¹/²” around the perimeter).
Sometimes, if you go too heavy on your raised bed underlayment, you end up with giant containers instead. Containers need drainage.
No biggie, I’ve done it myself.
Good luck!
you have no junctional drainage
Remove what’s beneath the bed. Dig up and loosen the soil below the bed before you start filling it back up.
As others mentioned, is there drainage under your bed? And I’d also add that topsoil is not potting soil. Topsoil is normally for lawns/in-ground gardens.