We built a vegetable wash station/play kitchen out of found wood (upcycled plywood or scraps from other people's projects). It has a 5 gallon bucket hanging above it for rainwater or hose water and a faucet from our local recycled hardware store, so it's functioning gravity fed wash station. We also put in a play stove and oven just for fun. Although if you're really crafty, you could make those functioning as well...in a kid friendly way.
We also have a huge trellis thing for our squash to grow up. It looks like only of those octagonal climbing structures at the playgrounds, but it's also made from upcycled 4x4 lumber (definitely not as pretty or geometric as the playground version), but the squash climb up the inside, and the kids climb up the outside.
Or you could grow the squash on the outside and the kids can have a dark(ish) fort on the inside. We have an old tire turned into a tire swing, a few other tires and a ladder made into an obstacle course, a pallet swing/bed under the grape arbor and a huge slip n slide made from all found materials (old vinyl tarp material 4'x15', 2 - 4"x6"x15' sticks on both sides of the vinyl to keep the water in, a slide made from 2 pallets - one side ladder, the other side covered in leftover laminate flooring for the slide (super slippery)....best thing ever for the kids during the summer!)
We also planted a few plants we didn't really care about throughout the yard so they could have something to grow all by themselves. I have a 2 year old and I have a small daycare for toddlers through age 7, and these things plus all the animals to help feed and water, they're pretty happy.
I wanted to build a full play structure/castle thing as well, but I'm a single mom with toddlers running around all the time, so I did break down and buy someone's old plastic play structure to add to the rest. Not too excited about having it, but it wasn't bought new and the kids enjoy it, so we'll live.
I don't know about designing a permaculture playground but....
How about rethinking the individual play structures.
A playhouse could be a trellis shaped like a house and covered in vines.
If the pathways were 2 feet wide and heavily mulched with wood chips they would make great bike trails.
Appropriately planted trees can be goal posts.
one of the water catchments can be a wading pool
Portland's got a lovely park, Westmoreland Park, constructed from natural materials, closer to their natural state than other wooden play structures. The picture doesn't show it, but its also got a basic metal frame and pile of large sticks, intended for kids to build structures. It also has a water play area and sand box. My kids, ages 2 and 5, love this park.
and now several minutes later...Wow! I just opened my own mental "Can O' Worms" - (And how ironic is that phrase, now seen through a Permaculture lens)
At first thought, "playground" brought forth visions of big plastic bouncy houses and big pressure treated wood forts and maybe some recycled rubber tire mulch to get some kind of "Green" rating or LEEDs (Leadership in Energy and Environmental Design) credits, and that brought a chuckle, as I tried to imagine fitting those kinds of components into what my mind envisions as "Permaculture" or a "Permaculture Design".
Now granted those are Todays "playgrounds", not that I'm old, but growing up "our playground" really wasn't much better - a bunch of galvanized pipe swing sets and monkey bars, and gigantic cement culverts set up like tunnels and turrets, but at least it was sand and pine straw that we landed on when we jumped out of the swing. (Is that even allowed anymore? ) One must jump right at the apex of the swing, at that moment you feel almost weightless!
(Grown man chuckles again - wondering if my knees could handle such frivolity anymore. ) But I digress....
- Problems into Solutions
The "Can O' Worms" opened when I realized - My DEFINITION of a "playground" is wrong! My mental picture of a "playground" is wrong!
And when I really sat and thought about it, as a kid, very seldom did I actually go to a playground. We played on them at school recess (Is that even allowed anymore? ), and occasionally we rode bikes to the city park and played. But when I honestly thought about it, my favorite "playground" was an old gnarly multi-branched Pink Crepe Myrtle tree in my front yard. My friends and I climbed up and down and all over that tree. It was a look out tower against marauding orcs or monsters invading our city block. It was the creepy hangman's gallows on Halloween night. It was a "quiet" place, where I could splay out among the branches and just relax and watch the world.
This may not be what you were intending or hoping for, but we "Practitioners of Permaculture" plant a lot of trees. Willow branches can be woven into some fantastic living structures. Close plantings of black locust in an orchard type setting could be coppiced and/or pollarded, providing wood for fuel and living structures for tree houses, or arched over into monkey bars, or sawn up into kid sized Lincoln Logs! How cool would that be,
These are just my quick random thoughts! But I hope this helps. I've found I'm choosing/needing to re-define a lot of things in my life, as a new/different set of values is slowly usurping my old ones.
Nature's a language; Can't you read?
~ The Smiths
Location: Zone 7b; West of the Great Dismal. On top of the Scarp
Its not an entire playground, but at our house, we've got a delightful play structure/chicken coop mashup. Living on an average-size urban lot, we definitely strive to stack functions! The kit was $50 from a neighbor who lost the momentum to build it, the green poly from our old, dysfunctional coop, and the logs from a cedar we took down to make room for more urban permie madness
There's a lot of fun things that can be done with cut logs. When we made our most recent garden bed, I edged it with hemlock rounds. These are great for sitting on while gardening, as well as for my toddler to walk across. I also enjoy walking across them! I have some vertical and some horizontal, to help with balance. They're various heights, too, to add to the fun.
You can also put bricks, thin log rounds or other things from kids to hop from on to another. Didn't we all play some variation or another of "hot lava" as children? My toddler also loves walking from brick or stepping stone to another.
If you've got boulders or large rocks on your property, you can all put them within jumping/hopping distance from each other. When I was a kid, my parents had an area they deposited all their large rocks. My neighbors and my brother and I all loved jumping from one to the next, claiming rocks as "ours," pretending they were thrones, etc, etc. These rocks, of course, also double as reptile habitat and as thermal mass.
Water features (streams, small ponds, fountains) are also great fun for kids, and double as insect, bird, and mammal habitat.
It's ironic, but the playstructure that my father-in-law bought for my son (with a slide, climbing wall, and fort) never gets used, but my son loves playing with sticks and walking on logs and rocks--perhaps largely because those are near where I'm working. Having the garden incorporating into the playstructures is great. Another such idea that incorportates play with food is having green beans and squash can grow up poles and make forts or tunnels: