Preparing a grow bed? When can I start planting in it?

[sheepdawg]

Hey everyone, I decided to convert a small area of my yard into a grow bed for future bonsai. It's basically going to be a simple patch of bare dirt with as many trees as possible growing in it, nothing fancy.

I tried weeding out the grass but was barely making any progress because it was a really thick mat, so I just got the roundup out and sprayed the area I want. The grass is starting to die, so I'm probably going to go through with a gardening fork and remove as much as I can.

I'm going to disturb as much of the soil as I can to try loosen it up by lifting it with a fork and just digging around. Would it be worth mixing in a manure or something similar when I'm doing this?

And how long do I have to wait to safely plant in the bed? Because of the roundup

Any other tips or tricks for getting this bed as good as possible?

Also, I'm planning on planting a Japanese Black Pine in there because I can't think of what else to do with it besides grow it out. Would this is alright? Would it be collectible in a few years?

Thanks

[treeman]

The most important thing is the drainage. The second most important thing is the drainage. If it drains well, all you need to do is turn it over with a fork after the weeds are dead. No need to remove them. No need to add anything to it. If the drainage is a bit slow, you will need to buy more soil (not mulch) and build it up so it's about six inches higher than the surrounding area. If you build up to 12 inches (30cm) it will be down to 15 cm (6 inches) within a year.
Then it should be in full sun and not full of roots from nearby trees. (this is a real problem!) After that break it up once more with a fork, rake it nice and even and plant. (wait for the weeds to rot away - watering helps) Mulch heavily and start to feed when growth is under way. You don't need to feed trees in the ground very much. Keep well weeded and water during dry periods. Don't leave anything in more than 2 years without cutting roots!
When you remove everything, you dig in the mulch, remove old roots and start again....

[shibui]

I have not experienced badly draining soil but I agree with Treeman that is important.
In most cases the soil will be fine as it is. If it is growing as many weeds as you imply it should be fine but I always add some manure or other fertiliser just to encourage even more growth. You will be more inclined to break up the hard soil if you feel you are doing good by digging in manure
My tip: Leave enough space between the trees so that you can move amongst them comfortably to prune, dig, spray or examine them all. They will also grow better with a bit of space. I plant mine about 50cm apart in the rows with 1.5m between rows to allow access and mowing.
You will need to mange the weeds while the trees grow - mow, mulch, spray or a combination of these.

You can plant immediately after using roundup (Glyphosate enters through the leaves, not through roots) but you obviously want to allow the roundup to kill the weeds before digging them up
If your weeds are creeping perennials like couch I would advise leaving it for a while after spraying. A lot of couch will re-sprout even after roundup so a second or third spray may be needed to kill it properly. Nothing worse than a perennial crop choked with couch grass You would be far better to spend a bit more time preparing properly and planting your trees properly at the correct time of year (winter/spring) than rushing in now.

Black pines are fine in a grow bed but you do need to manage the growth because they do not bud on bare wood. you will need to prune occasionally so that you'll still have some shoots with needles to build your tree after digging and pruning it. I think it is important to bare root plants as they go into grow beds. Nebari needs to be the best it can at this stage because when you dig it up the roots will be too thick to make changes then. one year I just took pines out of 11cm pots and planted the whole rootball in the beds without disturbing the roots. When I dug them several years later I had trees with a pot shaped nebari. A few roots had escaped and grown into the soil but the mass in the pot had just thickened and joined up into a solid woody mass (with pot shaped inverse taper).