Blackthumb: Houseplant care

KTPlants

In-app purchases

About this app

Do your plants keep dying? You're not alone, and it's probably not your fault.

Most plants fail because of one problem: light. Too little and they slowly starve. Too much and they burn out. Blackthumb gives you a Light Score for every plant and location in your home so you finally know what's going on.

— LIGHT SCORE CALCULATOR
Stop guessing. Enter your light readings (in lux, fc, or PPFD) and Blackthumb calculates your plant's Daily Light Integral (DLI) — the actual amount of usable light it receives each day. See instantly whether your Monstera is getting enough light in that corner, or if your grow light is doing its job. Compare against your plant's ideal range and get a clear "too low / in range / too high" rating.

Track natural light and grow light separately. See a confidence score that improves as you log more readings. Powered by real plant science, not vague color zones.

— CARE REMINDERS THAT ACTUALLY WORK
Set reminders for watering, fertilizing, rotating, misting, pruning, repotting, pest treatment, and health checks — for any plant or location. Snooze what you need to, perform what's due, and never wonder "did I water that one?" again.

Sub-reminders make your care routine smarter: set a fertilizing reminder that automatically triggers every 3rd time you water. No manual tracking needed.

— ORGANIZE BY SPACE, NOT JUST SPECIES
Your plants live in specific places — a bright windowsill, a dim shelf, a grow tent. Blackthumb organizes around locations (Living Room, Bedroom, Balcony) so you can see everything in a space at once and manage care by room.

Create collections to group plants however makes sense to you: new cuttings, wishlist, plants to watch, seasonal rotation.

— FULL CARE HISTORY
Every watering, every fertilizer, every repot — logged with notes. See your plant's complete care timeline at a glance and spot patterns before problems start.

— FREE TO START, PREMIUM WHEN YOU'RE READY
Blackthumb is free to download. Start tracking your plants immediately. Upgrade to Premium for unlimited plants, unlimited locations, all reminder types, and the Light Score Calculator.

Built for people who kill plants — and want to stop.

What’s new

##Updates to DLI calculator accuracy
##UI fixes