I have found 2 good solutions for my plants whenever I travel..
The first solution - MUM. Yup. I gave my keys to my mum, who promised she'd drop by occasionally to water them.. and of course, she did. And she tidied up my garden too.. Thank God for mothers and especially for mine...! :)
The second solution - Zip-lock bags. These ones I weren't so sure about.
But, after my recent losses to soil mealies and red spider mites, I have no more edibles in my garden, apart from my mint collection, a lonely parsley and 2 purple chilli (who have survived most amazingly... I was going to throw them away when I spotted new baby leaves).
Most of them are currently planted in small pots, so before I went away, I gave them a good watering, put them into a few ziplock bags and told my mum to skip the watering for these plants. I did the same to the african violets I was propagating.
And oh... when I came back, my plants were growing well and comfortably inside the zip-lock bags. It was like a little greenhouse for them, keeping them in a humid environment and protecting them from the strong winds and heavy rains.