The different areas/biomes to the north, east, south and west give you different kinds of seeds/crops. Desert seeds don’t require much water but take longer to grow (I don’t think prickly pears need any water). Plains seeds need lots of water but grow quickly. I’m a bit fuzzy on the jungle and tundra areas because by that point I’ve usually amassed so many seeds I’m not sure where they came from–I need to look into that at the market. Crops that require water though won’t grow until they’re watered, so it’s super important.
Fertiliser improves the crop making it more valuable (you’ll know when you’ve applied enough fertiliser because it stops you using any more). The added value isn’t separated out at market unfortunately, it’s just a lump sum for each crop, but you can see the difference with the crop pictures because they look bigger and/or happier.
As you weed, sow or till you build up an energy meter (at the bottom of the screen). When it fills up you become energised for a brief period and can weed, sow and till a lot faster. You can maintain this state by continuing to weed, sow and till before the energised gauge runs down. Several items upgrade your energised state eg. to make it last longer or double your damage and speed. Some items will charge your meter on tractor use or by killing enemies. It can be very powerful and useful.
One other tip: I would recommend using pickaxes before night time or weeding and sowing seeds because it’s easy to break the earth/crust in the wrong place when you’re trying to defend, dodge and attack! Pickaxes and expanding your plot is very important to manage your space, crops and defences.