I really wish they would make their minds up. First we had 20 moves, then they took 2 away now they have added them back again and then knocked them down to 15.
The key to success here, is to make as much grass as you can where the slime is and to try and make patches of it so that you have more room for your crops.
The easy part is getting the spider, and once he is out of the way, you have more room to grow grass and get your crops.
Make them cascade for extra value.