Can I hydrate my plants with ice in minecraft pe?

No… Unfortunately it has to be water

Nope, it has to be water. Here is a direct quote from the Minecraft wiki that explains it pretty well:

"Hydration
Conditions in which farmland is and is not hydrated.

A farmland block will be created dry. It will become hydrated if the following conditions are met:

1. Water up to four blocks away horizontally, including diagonals.
2. The water must be on the same level or 1 block above farmland block level.

The blocks between the farmland block and the water make no difference.

There's nothing the player can do to affect the rate at which farmland becomes hydrated. Each farmland block within a 9x9 grid of farmland with a single water block in the middle has exactly the same chance of becoming hydrated as a single farmland block in an ocean.

Farmland can also be hydrated by rain.

Different types of seeds grow faster on hydrated farmland than on dry farmland. Hydrated farmland will yield a fully developed wheat crop in a little over a single day/night cycle."