Posted: 26/04/2013 at 14:13
Between two and three weeks, depending a bit on weather conditions.
I have a few questions for you, though!
When did you "start" your pond?
How big is it?
Whereabouts in your garden is it?
What plants are there?
Where did the spawn come from? i.e. did a frog/toad lay it in your pond or did you bring it from somewhere else?
Newly hatched tadpoles eat the remains of their own egg sacs and then eat various algae and some semi-decaying vegetable matter before eventually becoming more-or-less carnivore, though will eat insect larvae. At a push, you could tie some small pieces of (raw) liver or red meat on a bit of string and suspend this in the pond water, though it wouldn't be a good idea to do this too much as young froglets/toadlets are very susceptible to problems caused by poor water quality.
I bet that if you google for more info as to what you could help with, food-wise, t'internet will probably come up with some ideas for you.