A weed is not always a weed.
It is wonderful that parents, educators, city recreation departments and others are singing the praises of "natural playgrounds" these days. The concept has been growing constantly, especially since the 2008 publication of Richard Louv's book "Last Child in the Woods" introduced NDD or 'Nature Deficit Disorder." It is more than a romantic notion. There is actual science behind the benefits of children playing in nature.
The reality is that when it comes down to deciding on a natural playground, those responsible are often forced to cave into the simplicity and apparent safety of catalogue 2, page 93 through 95. It's ASTM certified so you can't get sued. And, if you cover the whole place in rubber surfacing there will be no injuries (or law suits), right? And, then your maintenance guy will stop complaining, too, because there is virtually no upkeep.
Yes, page 93 - 95 is easier, but there are problems with that choice.
One is the reality of cost. When you factor in the cost of rubber safety surfacing you can easily plan on shooting 1/3 of your budget (on a good day). So you can't buy as much play equipment. Reality bites.
Second is the reality of affordances. Affordances - or how much cool fun you can get out of each piece of equipment - should be many. But, by blowing all of your money being safety- and maintenance-conscious components you have a sparse, cold (even when scorched by the sun) playground that is boring after no time at all. All of that money you worked so hard to raise didn't go very far. As much as I love swings and slides they do their job pretty much the same way each and every time they are used so their affordances are low compared to, say, sand that can be different every time you start messing with it.
A natural playspace affords an almost limitless collection of play options that help build communication skills, negotiating skills, executive function, immunity - I could go on. In spite of being someone who thinks that play just for the sake of play is enough, I am forced to admit that its learning benefits are immense and just the beginning of what free play can provide for children (if grownups don't get in the way too much).
Third is the reality of maintenance. This is a straw man in the argument. It's not a real battle if put in perspective. We should not begrudge the maintenance required to keep a natural playspace playable. Look at it instead as stewardship. And not in the sense of the word that just means taking care of something (maintaining), but instead stewardship as in taking care of and honoring a natural space and the children who will find wonder there. Maintenance here is not a dirty word. We are caring for, maintaining, preserving and sustaining a space where the wonders of childhood can unfold and the brains and bodies of those beautiful little beings can thrive.
So, go for it. Mix playground equipment with fruit-bearing trees. Stop at the required fall zone rubber surfacing and cover the rest of the playground in grass and flowers and sand and, yes, even water and mud! To be good stewards of our children's play spaces and their childhoods themselves, we should "buck up" and sweep and dig and wash muddy clothes and rinse dirt-covered hands and feet. Be stewards of these magnificent spaces. Great things are usually worth a little extra effort.