Hello there! I was just wondering if trees need some space between them in order to grow (like Animal Crossing games for example)? Furthermore, do you need to water them too? Thank You!
That depends on if you're talking about Fruit Trees or the basic Oak/Maple/Pine trees! Fruit trees need a clear zone of one empty square on all sides (a 3x3 grid, basically, with the tree in the center square) to reach maturity. Oak, Maple, and Pine trees will sprout and reach sapling size even if planted right next to another tree, but they cannot reach their full maturity if within one square of a fully grown tree, so the 3x3 square technique is better if you're planting them to harvest sap or make a nice decorative park. (This also makes getting between them to harvest your tappers much, much easier!) No trees of either type need to be watered. Fruit trees grow on a set schedule (assuming the ground on all sides in the 3x3 grid is clear) and will reach maturity in 28 days. Oaks/Maples/Pines have a 20% chance to grow to the next stage every day except in the winter, meaning their average time to develop into a full-grown tree is about 20 days, though since there's an element of chance they can remain saplings for a discouragingly long time, sometimes.
I know fruit trees need all 8 spaces around them to be clear to grow, but I'm not too sure about the 'wild' trees. I think they may be able to be right beside each other. edit: What she said! haha
In the case of fruit trees, nope. In fact the game won't even let you plant a fruit tree too close to another one. You'll get an error message if you try. In the case of regular trees, you can plant them anywhere, they just won't get to full size if they're too close to an already mature tree. Regular trees will develop into saplings, so you can get a pretty dense forested area if you let the seeds spread and grow on their own, but the mature trees will always be at least one space apart, so there's some overlap in the zones there.
You can also plant fruit trees in the green house. The same 3x3 rules apply. You can also plant them in the floor (non dirt portion of the green house) but not directly adjacent to the border strip. Measure from the wall, go in one space, make sure you can walk completely around the area and plant your fruit tree. You can also plant them in the tillable dirt in the green house, again, that border strip can't be part of the 3x3. Once the tree has grown and is producing fruit you can plant veggies all the way up to the trunk, but planting anything next to it or planting the tree next to the border strip will stop its growth
Here's a good page to show tree and sprinkler placement in the greenhouse. https://stardewvalleywiki.com/Greenhouse You can't place the two left-most (iridium) sprinklers until the trees are fully grown as they will impede it because they are within the surrounding square area.