Sowing calendars

I've come to the conclusion, after at least 40 years,  that I need to begin to be a little more organised.  In the spring I get all excited and sow anything and everything, fill up the patch at planting out and even if I wanted to successional sow, I haven't got the space.  So I thought a sowing calendar might be a reminder to be less enthusiastic in spring, leaving room for later sowing.  I run a desultory spreadsheet but the novelty wanes as the season progresses, I forget to look at my written garden book, so I thought I could run a second 'garden' calendar on my tablet completely separate from the existing humdrum daily household one, but I've yet to figure out how to have two distinct calendars.  The one I have syncs all together into one  display.  Next thought was an app with a reminder feature.  I'm still investigating than but I was after something simple.

I've heard PP talk about her sowing reminder, so my question is:  Does anyone have any bright ideas? What do you do to remind you about sowing at times other than spring?

Use the power of the 'Force' JJB, just like me. In other words just blag it!