Atomicrops

Year: 1

I got lucky and picked up the Organic Armor upgrade in my run. I only got hit once after I picked up the organic heart, and I was still able to get the achievement.

Edit: I got this achievement shortly before the Doom and Bloom update came to console. I have not been able to check and see if this method still works. Worked on June 7th, 2021. Feel free to let me know in the comments if this no longer works due to updates or patches.

Working as of 8-20-21.

The main thing to keep in mind is that if you get hit at all, you can dashboard quit the game. When you reload it will resume from your last completed day (as long as you passed day 1). Another nice side effect of this is that you keep all your cornucopias that you collected if you dashboard quit/resume during a season festival, which happens after a boss fight. Purposely dashboard quitting at the last boss, collecting the rewards then spending all your cashews at the casino can boost your cornucopias so that you can unlock better permanent rewards. Obviously it is best that you attempt this on year 1, after you have many permanent unlocks and have played through many seasons.