How do I get my neighbors to harvest my crops when I want them to?

For three horseshoes you can buy signs, one says tend here and the other says hands off.   These signs are meant for just what they say, as you can see with mine.

There will be times when you are doing a task and need to harvest your own crop, than you use the hands off sign.  The tend sign here is perfect when you are growing cotton, which takes four days.  For every neighbor that fertilizes the cotton crop, 23 hours will be eliminated from the time it is ready to harvest, that is why you want the tend here sign.  Happy farming!