yes, you CAN stack modifiers, however, not of the same type. Example, you can stack a pixie on top of the red barn farm, but you can NOT stack Maelstrom, Burning and Regular Snap Dragons together. You can only use ONE Snap dragon plant as a like. So, let's say you're gardening Pink Dandelions. The likes are:
1) Tropical Garden Gnome 2) Potted Cat Tail 3) Ball of Blue yarn 4) Pixie (spell) 5) Botanical Garden House OR Red Barn Farm (only one) 6) Maelstrom Snap Dragon OR Burning Snap Dragon OR Regular Snap Dragon (only one)
You can have all 6 of those, but on entries 5 and 6, you can only have ONE of those. Any more than one of item 6 won't count. A seed can't be planted in more than one house, but I wanted to show you the whole list from above.