Wow, you offer quite a lot indeed!
Firstly, are you a council or private run site? If a council site, then there are some general limitations about how much you can put up allotment charges compared to how much other leisure costs in the council are going up.
You're unlikely to be on a residential electricity tariff, so your tariff is likely to have increased (or be about to) significantly. Consider what your costs are likely to be over the next 12 months and how much income you need to raise in order to be sure of covering it. Or if that's too much, decide whether you can continue to run all your electric appliances.
Ditto for your water costs.
If you can't cover the costs, then you have to put up rents to cover it, or reduce what your costs are. Tenants might be understanding if you put the full details before them.
For example, if you pay for the bark chips, consider how much that costs (and whether you can recoup that separately from plot rent).
I am up north and don't offer what you offer, but we are middle of the road - high for plot charges. A full size plot (176 - 300 sq yards) is £96 p.a. (concessions less). Half that price for 76 - 175 sq yards. Less again for the smallest plots.
We charge £40 initial deposit (concessions less), returnable if the plot is in as good a condition as it was when let and there have been no warning letters.
Hope that gives you a ballpark idea.