As it is now, farming is the main suspect in the brainless grinding department. The moment you get seeds, it's just constant menial labour from which the only diversion is fucking around trellises, like the devil spawns they are.
I'm probably not the first one to propose this, but i'd say it's long needed - fertiliser and nutrients system for farming. Kinda like with cooking (and to way bigger extent alchemy), putting some randomness into farming would make it it's own thing, rather than a slave task.
The basic premise would be to add another layer to each tilled farm plot - nutrients level, a set of 3 stats that influence the speed (and maybe quality growth) of all crops planted. Let's call them A, B and C for now. Each plot would start with (A 0, B 0, C 0) and in that state all crops would have a relative 100% growth time. Each crop would get an unique set of nutrient needs, either positive or negative. A plant with a set (A ++, B+, C-) would drain a lot of nutrient A, some of B and deposit nutrient C into the plot. Plant with set (A--, B-, C+) would do the opposite. Plants would get bonus growth speed for all the required nutrients in the plot they need + they would lose growth speed the more of the nutrient they don't use. The whole premise would motivate people to play around with their crop placement, rotating them between each harvest. Instead of speed that could also be the quality growth (without going into negatives, as that's not fun) as slower growth rate might be too punishing + that wouldn't hurt mass farming for stuff like hemp.
Now for the way of finding out the right combinations, I'd use the primary colors - Red, Yellow and Blue for each of the nutrients. A (0,0,0) plot would be white, when (100;100;100) one would be black. (0;100;100) would be pure green etc. Of course i don't suggest making each farm looking like a rainbow barf. The acces to the colours could be locked behind heart magic (let's say 500EXP, unlocked by druidic rite - a totally random number for now). Either that, or to make an item similar to rustroot extract, preferably from semi-rare materials (fairy shrooms, heartwood leaves, kelp and such) that would let you see the colors of your farm for a few times before you have to refill it. That way a farmer could make some estimations between harvests and plan accordingly.
Another level of depth would be to add fertilisers. Akin to alchemy, but not that terribly complex, they could be a fast-yet-random way to add (and/or remove?) nutrients to farm plots. They would be made from non-farmable materials not to encourage spiraling. I was thinking insect meat + few types of rocks (dolomite, limestone etc. without going into chemistry), with their quality resulting in a bigger quantity of final product only. Fertilisers should be easy to make en masse, let's say 10 pieces from one craft, with some mechanic to spread them easily. Not to make it too easy to min-max, a plot could only be fertilised once per harvest.
The main premise here is to make farming NOT encourage grinding and spiraling, so if any part of it sounds like a spiral-in-the-making, that's not the intention here. If you think the whole idea is too extreme (as it probably is) i still welcome some discussion on this subject, as i strongly belive each part of haven should be it's own unique thing and we should encourage all the changes that make it so, even if they hurt the grindan, spiral-esque, bland and cheezy adventure H&H is.