What I do is make sure I have an area clear of items, then plop as many of the type of dirt I need to be covered by a Level 3 gardening spell. I can get 27 MEDIUM plots covered by a bunch of Level 3 spells and only have to cast them once. my rows are as follows:
X X X X X X X X X X X X X X X X X X X X X X X X X X X
I hope all the spacing stays true. It ALMOST looks like a heart. I find that in order to guarantee I line it up right, I have to go to the LAST row (the one with 2 plots in it), spin my character around so Im facing the 2-plot row, and then plop down my gardening field. If I do that, I can cast L5 Bug Killers (25 energy), L3 Sun (15 Energy), L3 Water (15 Energy), L3 Bees (15 Energy) and L3 Music (15 Energy), for a total of 85 (our of 86) energy used, and do it twice a day without any issues. I'm a Grandmaster Gardener and until I need to do any new gardening, I'm gonna stick with the medium plots of land cause I have TONS of seeds and very little fuss with this method :)
Now that you know that, you also need to know that I have a weapons rack 6 paces, one of those Mooshu guard towers 3 paces, an "urned plant" 2 paces, and a larger concrete statue about 4 paces away from the same grouping of plots. my advise to you is to keep them far enough away so you can see clearly, and it not interfere with your walking to harvest your plants and don't worry about it :)
If you ever find some Malestrom Snapdragon, dont throw them away or sell them. You can buy some from a guy in Nordrilund ( I think, might be one of the other four places) in Wintertusk. In my opinion, they are the best plant because they give you a lot of Aether and Sunstones during a regular harvest, plus vines and braided vines when you elder harvest them. They require a large soil plot, but you might be able to fit 9 or 12 into a "rank 3 growing spell" zone.
They do not give amber, however, which I have heard and experienced happens to be the most difficult reagent to find.