I would like to be able to make "garden" areas or "planters" where you could grow native (and earth) plants for decorative value, which could only be "harvested" by the player and wouldn't die if you just leave it as a decoration (assuming it needed to be cultivated). Trees and native plants should be a renewable/plant-able resource in any dirt patch (not farm) but I would be happy with planters. I would want to keep the planters small, regardless of the size of the plant, so that you can make nice clusters of plants. If you make the planter place-able just below the surface of terrain, then you could create very interesting natural-looking landscapes as well as terraced gardens for your colonies. Since you can place a variety of terrain, this would provide a much more interesting variety of landscape designs than having just object decorations. I know that rendering plants is not free for the processor, so if there needs to be a limit to the number of planters in the colony, that's fine. You can use free camera mode to see underground, if you need to pick up or re-position them.
Eventually, I would also like to see water sources/fountains made available for gardens, but I know that water is extremely hazardous right now as a terrain feature. (You cannot remove water by filling it in, once it is breached -- I found that out trying to mine at a beach.) Your fountain could become a new lake, if you're not careful. LoL.