The main upside-down tomato problems are rapid soil drying, blossom end rot, stem breakage, and poor sunlight. Each of these hanging tomato issues has a fix. You just need to know why the problem happens in the first place.
I dealt with blossom end rot my very first season of upside-down growing. Dark sunken spots ruined about half my tomatoes. The fix turned out to be simple. I started watering at the same times every day instead of when I thought about it. The rot stopped showing up on new fruit within two weeks of steady watering.
Blossom end rot happens because of moisture swings. Your soil lacks nothing. Iowa State Extension backs this up. Your plant needs steady water to move calcium from soil into fruit. When soil goes from soaked to bone dry, calcium flow gets blocked. The fruit bottoms turn black. Steady watering fixes this issue.
Rapid drying ranks as the biggest upside down growing challenges for most growers. Your hanging bucket loses water faster than any ground pot. Air hits it from all sides. Wind pulls moisture out through the soil and stem hole. You may need to water twice daily during hot spells. A larger container helps hold moisture longer.
Stem breakage becomes a real threat when heavy fruit loads up on the curved stem. The plant bent upward after you hung it. That bent part now holds all your growing tomatoes. Too much fruit can snap the stem right at the curve. Pick tomatoes as soon as they ripen. Choose smaller fruited types that won't stress the stem.
Poor sunlight causes weak plants with few fruit. The bucket itself can shade young plants below it. Nearby walls and fences block light you might not notice. Your tomatoes need 6-8 hours of direct sun to produce well. Move containers to sunnier spots if plants look leggy. Watch where shadows fall all day.
To fix problems, check watering first. Always test soil moisture. Troubleshooting inverted tomatoes comes down to this one step. Most hanging tomato issues trace back to too little water or uneven timing. Fix that and many other problems fade away. Check your plants morning and evening when it's hot.
Fruit cracking shows up when you water too little, then way too much at once. The tomato skin can't stretch fast enough. This leaves ugly splits in your fruit. Iowa State Extension lists uneven moisture as the cause here too. Daily watering at set times prevents both blossom end rot and cracking on your harvest.
Read the full article: How to Grow Tomatoes Upside Down Successfully
