30 Water drops
Start off by making matches next to the water barrels as soon as possible to get the water flowing.
You need a lot of water drops, and in a perfect game, water would just automatically jump out and make +5 rows for us, but reality dictates otherwise.
Keep making matches next to the mushrooms to make babies. You're going to need a lot of them too to grow into adults and collect them. The water drops jumping from the barrels help in that they can also make matches next to the mushrooms. It's a very trying level.
(Try to keep a shovel towards the end of the level in case you only need one or two of a crop, and can then use the shovel on a single one to make the points. You really need the Hitter Companion, unlocked on level 990)