Looks good!

I’m not an expert but I did try this on a tiny scale with pots and a tiny patch of soil. It was a learning curve…

I had a hell of a time with pests when doing things without pesticides so you might want to add some decoy plants for them to attack instead, plants that will repel, and ones to attract beneficial insects. There are guides on this.

You might want to look at crop rotation if doing this long term because planning plantings in a certain order can reduce the need for adding fertiliser. ie. Legumes like beans or peas first enrich the soil with nitrogen, then plant stuff in decreasing order of heavy feeding needs as that gets depleted, re-nitrogen that spot by planting legumes again.

Companion planting guides can probably help too as planting similar types together can ‘concentrate’ a particular pest or disease in that area and make it worse for all of them.

I also used manual pest management methods like spraying soapy water and then when that didn’t do enough ended up straight up picking and wiping off pests such as thrips by hand. The Eco “pest spray” from Bunnings that was safe for bees didn’t really do a lot tbh. There’s neem oil but I saw something about it not being good to use on edible fruit and veg (?) so you might want to read up if you go that way.

For snails going after young seedlings I tended to bring pots inside at night or cover pots with overturned plastic tubs. The tubs may still work for a few individual seedlings in-ground but it may not be practical for larger areas with many plants.

For plants that weren’t covered I made it a nightly habit to pop out in the evening/night when the snails like to feed and do a quick check over with a torch.

There are things like crushed eggshells and coffee grounds to discourage slugs and snails from plants, saucers of beer, a lot of things for snails if you don’t have time for picking them off. Seeing as I didn’t have a big area or huge number of veg I found it most efficient to just step out and yeet them by hand.

I think I saw a Harlequin bug once. I don’t know much about them or if they’re safe to touch or crush but you can knock them into soapy water to drown. Try a jar of soapy water and scrape in with the lip or knock them into a bucket. https://www.diggers.com.au/blogs/learn/harlequin-bugs

Also I see cabbage - strongly consider placing decoy decorations like fake white butterflies as that might discourage cabbage moths. There are guides to cutting out butterfly shapes from white plastic (from milk or margarine containers) drawing on black markings with a permanent texta like a Sharpie, and gluing or pinning the fakes to sticks to poke in the ground.

I tried the yellow sticky trap sheets that are supposed to trap and kill pests, cheap on eBay, however I found that they trap and kill beneficial insects as well. Big thumbs down from me and I stopped using them. They were killing my pest-eaters and my pollinators.

Consider your choice of varieties too, heirloom varieties can be more vulnerable to disease and need more careful attention.

For example I found cucurbits can be really susceptible to powdery mildew. I used the Eco fungicide from Bunnings in large amounts, and later found out you can get the active chemical cheaper in bulk and mix it into water. I’ll get back to you on what it is in a bit if you’re interested, it’s a food safe supplement that alters ph to discourage fungus. Forgot the name.

Definitely consider training pumpkins and zucchini upwards if possible to keep them off the ground to reduce fungal infections, or buy bush cultivars.

Not foolproof though as my heirloom bush variety zucchini did get a little mildew and require spraying. The Jack Be Little pumpkin I staked up still suffered terribly from mildew. The Golden Nugget pumpkins (I think that’s the variety?) were bush types and a bit more resilient against mildew but got eaten by something, probably rats. My snow peas also straight up got munched.

So yeah. It might be smart to protect your plants physically from being eaten. You can do this while they’re seedlings with cloches cut from soft drink bottles but they quickly outgrow that.

Netting is good as things get bigger, you can drape it over star posts driven into the corners and fix it at the bottom with U shaped metal pins but do make sure to use the kind of netting that wildlife can’t get caught in, there are laws about that now. The upside is the holes are smaller. Chicken wire might prevent chewing through but with holes over a certain size rats and mice can get in. I didn’t have a big enough space to implement but there will be guides.

You can also build cold frame boxes from wood and plastic but that’s getting a bit elaborate.

Edit: Oh yes, and you can buy beneficial bugs online that will eat the pests! Just know that you can release them and they might just eat up once and then bugger off. This is especially true if you order the adults.

It might be better for long term to plant the attractants in order to create a bit of an ecosystem that encourages them to come and stick around.

But if you’ve got a heavy infestation and need help fast don’t worry, you can just order the bugs as eggs or even as adults and hit it hard.

What's in the middle trench with the chicken wire over it?