Ground growing

[Trimmy]

If you have running grass like I have, nothing will slow it down apart from the lawn mower and whipper snipper. But of course you don't want to get too close to valuable plants with these tools. I tried growing some raised beds and the grass ran up through the bottom and through all the soil. The only fix was to disassemble the bed.

[SuperBonSaiyan]

Weed mat is of different qualities. Even the green shed has a range of different qualities and prices.
I have only used the cheaper woven weed mat and only for fixed installation. It does break down and leaves miles of tough plastic strips. When weeds grow through the fabric it can be real difficult to remove.
For the grow bed you will be taking it off every year or 2 to access the roots so probably better to go for reasonable quality.
Or go for something that's biodegradable. Sheet mulch with cardboard or newspaper covered with something to hold it down against wind works very well and should be broken down by digging time. If it decays early then simply put on another layer.

Preparation depends on the weeds you are dealing with. Annual weeds are easy. Just laying the weed mat or sheet mulch over them should kill them.
Perennials are another problem altogether. Couch, bent grass, oxalis and sorrel are the biggest menace up here. All will grow from pieces of root and most will find a way through weed mat.
I try to start with a cleanish area so spray with glyphosate now to kill off as many weeds as possible before planting. Spray well before any digging if there are perennials as most can grow from small pieces of root.

Weed mat is not a magic bullet. Unfortunately weeds will still come - seeds blown in on the wind, birds or from some organic fertilisers so you will still need to do some spot weeding as they turn up. The trick is to try to keep ahead of them so try to weed well before they set seed and spread further.

Raised bed on weed mat depends on how high the bed is. If it's over 50 cm high you could use wed mat under but shallower it will tend to get in the way when digging and may even prevent tree roots from going deep to get good growth.

I'm planning on doing a low bed, so I'll make sure to cut a hole through the fabric where I'm planting.

I know what you mean about the little strips of plastic, I removed it from my front yard and I'm still finding little ribbons now and again.

Do I need to have anything on top of my weed mat? (E.g. pebbles or mulch), or can I just leave it bare? Also, will mud seep through the weed mat? If it does I'll likely put down some pebbles to prevent getting muddy boots every time I go into the garden.

[shibui]

The weed mat I have used is quite light so will blow around if not help down. If it moves that will also allow light in to help the weeds get going too so needs to be held down tight as possible to be most effective. There are weed mat pins to peg it down along edges or can be covered with mulch of some sort. Depends on the size and shape of the mat as to what will be effective and practical.

Whether mud will seep up through depends very much on the type of soil you have. Fine, clay soils stay wet and the fine particles can seep through but most loamy and sandy soils should not be a problem. Your plan was to fill the bed with sandy soil which should not turn muddy and should not filter through the weed mat. You probably won't be in there that often anyway. If you find any problem stone mulch or something else can be added later.

If you have running grass like I have, nothing will slow it down apart from the lawn mower and whipper snipper. But of course you don't want to get too close to valuable plants with these tools. I tried growing some raised beds and the grass ran up through the bottom and through all the soil. The only fix was to disassemble the bed.

Glyphosate is useful on running weeds because it is systemic. I still spray along the rows, being careful not to let it drift onto the trees. In winter when there's no leaves on deciduous I can spray closer as glyphosate only enters through leaves and open wounds. Couch and sorrel are not easy to control but persistence and repeat treatment does help. I agree that the best solution is complete start again if they have been allowed to get away though.

[SuperBonSaiyan]

The weed mat I have used is quite light so will blow around if not help down. If it moves that will also allow light in to help the weeds get going too so needs to be held down tight as possible to be most effective. There are weed mat pins to peg it down along edges or can be covered with mulch of some sort. Depends on the size and shape of the mat as to what will be effective and practical.

Whether mud will seep up through depends very much on the type of soil you have. Fine, clay soils stay wet and the fine particles can seep through but most loamy and sandy soils should not be a problem. Your plan was to fill the bed with sandy soil which should not turn muddy and should not filter through the weed mat. You probably won't be in there that often anyway. If you find any problem stone mulch or something else can be added later.

My soil is very heavy red clay. The sand was only going to be inside the bed, so the outside (where I want to control the weeds with the mat) will likely still get muddy... So it looks like (eventually) I'll top it off with stone.

[shibui]

I can see you'll be out each day to do the rounds and check how the trees are doing. Definitely put something either under or over the weed mat to stop the mud seeping through.

[Jan]

Weed mat didn't work for me; the black woven one (that ends up black strips) didn't let enough water through, the thin black one (a bit like Chux wipes) didn't keep the weeds at bay so I went with Geo Textile (from "that" green shed). It looks like white felt and is meant for jobs like keeping soil and drainage gravel layers in retaining walls separated. It works a treat as weed-mat in my covered orchard. I've covered it with a layer of crushed shale (used locally as road base and driveway material) to keep it anchored in our windy area. It's been in for a few year now with no deterioration and no weed issues.

Jan

[shibui]

Geotex is definitely worth considering. Made mostly from recycled PET bottles and seems to last indefinitely, or at least a very long time.
Weeds will germinate on top with roots growing through but as a surface around a raised bed spraying or otherwise dealing with annual weeds should be no problem.
Not sure where the green shed gets supplies but we have a factory that makes similar in Albury.

[PWC]

You should be able to find supplies of geo matting from Plumbing supply companies, I work for one and we stock it in 50 meter roles in various widths starting from 600mm to 2000 mm.

[bonsaibrightlogpolar]

If you have running grass like I have, nothing will slow it down apart from the lawn mower and whipper snipper. But of course you don't want to get too close to valuable plants with these tools. I tried growing some raised beds and the grass ran up through the bottom and through all the soil. The only fix was to disassemble the bed.

Dealing with a runaway grass situation can be a real challenge, but fear not, my friend. You're on the right track with the trusty lawn mower and whipper snipper to keep that grass in check. Just gotta be mindful of the precious plants nearby, ya know? And kudos to you for giving raised beds a shot, although it's a bummer that the grass decided to play "up through the bottom" game. Sometimes, disassembling is the way to go to reclaim your soil kingdom.

[SuperBonSaiyan]

Raised bed on weed mat depends on how high the bed is. If it's over 50 cm high you could use wed mat under but shallower it will tend to get in the way when digging and may even prevent tree roots from going deep to get good growth.

To get the benefit of ground growing, is it better to have a shallow bed? Basically I'm unsure whether the benefit of ground growing is because the tree has access to the Earth (shallower bed), or whether it's because it's very free draining (higher bed).

[shibui]

Not sure that depth of the bed has anything to do with it.
Growth depends on light, nutrient and water availability and space for roots to run. Nutrients are generally in better supply in soil than in pots where they get leached out quick with increased watering. Good root run allows the trees to collect nutrients from more space.

Higher raised beds dry out quicker than lower beds or direct in ground so moisture could be a limiting factor in higher raised beds. Provided you can keep the water up to it and enough nutrients in the root zone there should be little difference between high and low raised beds. I would be wary of taller raised beds if watering might be an issue. Dry soils will encourage roots to grow deeper for permanent water. Might make it harder to dig when you need to

Real growth rates in soil will depend on the soil type, water and nutrient availability and competition from other plants Theoretical comparisons probably don't mean much until you have clarified the values of the local soils.

[SuperBonSaiyan]

Not sure that depth of the bed has anything to do with it.
Growth depends on light, nutrient and water availability and space for roots to run. Nutrients are generally in better supply in soil than in pots where they get leached out quick with increased watering. Good root run allows the trees to collect nutrients from more space.

Higher raised beds dry out quicker than lower beds or direct in ground so moisture could be a limiting factor in higher raised beds. Provided you can keep the water up to it and enough nutrients in the root zone there should be little difference between high and low raised beds. I would be wary of taller raised beds if watering might be an issue. Dry soils will encourage roots to grow deeper for permanent water. Might make it harder to dig when you need to

Real growth rates in soil will depend on the soil type, water and nutrient availability and competition from other plants Theoretical comparisons probably don't mean much until you have clarified the values of the local soils.

I'd rather water less so I think I'll go for a shallow bed. Also means I need to fill it with less soil (even cheap soil costs money).

I'm ok with roots running into the native soil, even if they are more difficult to dig later. Theoretically, the bigger the scar underneath, the more laterally the roots should grow.

I've been told my native soil is quite nutrient dense (red clay) though poor draining son hopefully the roots that grow into it aren't able to thicken significantly in 2-3 years between digs.

[Trimmy]

Digging out of clay is easy when the soil is damp all the way through in winter after a lot of rain. When it's dry in summer you'll be snapping roots all over the place. Even heavy watering with a hose may not be enough.

[SuperBonSaiyan]

Digging out of clay is easy when the soil is damp all the way through in winter after a lot of rain. When it's dry in summer you'll be snapping roots all over the place. Even heavy watering with a hose may not be enough.

I'm planning to treat each dig like a repot. I figure I should build nebari whilst it's in the ground.

[shibui]

In my experience digging heavy clay when it is wet is very difficult. The clay soil sticks to the shovel, your boots, everything. Then it is real hard to get the clay soil off the roots without breaking roots. Need to soak in water or use lots of water through the hose to wash it away. Clay grows good trees but difficult to work. Definitely add compost, gypsum or sand to clay soils to help open the structure a bit.
If the soil is easy to work when wet then it is not clay.

I have found that digging faster growing trees each winter is a great idea. As you say, treat each as a repot to cut and reposition roots to improve nebari.
I leave slower growing species for 2 years, sometimes longer. Pines and junipers are slower and the roots do not thicken and get hard so They can be left for 4-5 years at a time to thicken and are still easy to dig.