Plant care apps (PictureThis, Planta, Greg) and pet care apps (11pets, Pawtrack) seem niche but pop up frequently in mobile system design interviews. They combine ML image recognition, schedule management, push notifications, and the unique challenge of building habits around things that cannot remind you themselves.
Functional requirements
- Add plants/pets to your collection
- Identify a plant via photo (ML)
- Schedule care tasks (water, fertilize, vet appointment)
- Reminders before tasks are due
- Track history of completed tasks
- Personalized care recommendations based on species
Plant identification
Image classification model:
- Cloud model (PictureThis-style): high accuracy, ~99%, requires network
- On-device model: 80–95%, works offline
- Hybrid: on-device for common species, cloud for unknown
Many apps offer expert botanist verification for uncertain identifications — paid premium feature.
Care schedule
Each plant/pet has tasks:
- Recurring (water every 5 days, walk daily)
- One-time (annual vet visit)
- Adaptive (based on season, weather, growth)
The “recurring” patterns are similar to a habit tracker but per-entity rather than per-user habit.
Adaptive scheduling
Smart apps adjust based on:
- Weather (rainy week → skip watering)
- Season (winter dormancy)
- Plant growth (younger plants need different care)
- User patterns (often forgets to water; remind earlier)
Weather data integration via OpenWeatherMap or similar.
Reminders
Local notifications scheduled via:
- iOS: UNUserNotificationCenter
- Android: AlarmManager + WorkManager
Constraints:
- iOS limit: 64 pending notifications
- Schedule a sliding window (next 64 tasks)
- Re-schedule when user completes / postpones / changes settings
Photos
User photos for each plant/pet over time:
- Track growth visually
- Spot disease (yellowing leaves)
- Compare against ML reference for diagnosis
Storage: local photos for the user’s collection; cloud sync optional.
Care recommendations
Per species:
- Water schedule
- Sunlight needs
- Soil type
- Common diseases
- Optimal temperature range
Curated database of thousands of species. Recommendations adapted to user’s climate (zip code → climate zone).
Multi-user (household)
Family members share plant/pet care:
- Shared collection
- “Who watered last” tracking
- Notifications sent to whoever is responsible today
Offline behavior
- Care schedule is local — works offline
- Plant ID requires network for cloud-based; local model for offline
- Photos stored locally first; sync to cloud when online
Battery and data
Light. Care apps are check-and-leave. Notifications are scheduled locally.
Frequently Asked Questions
How accurate is plant identification?
Cloud models hit 95%+ on common houseplants. Edge cases (rare species, ambiguous flowers) drop to 70–80%. Many apps offer expert review.
How do you handle a user with 100+ plants?
Bulk operations. “Mark all as watered.” Group plants by location. Filtered views.
What about pet medical records?
Many apps integrate with vet records via export. Storage encrypted; some apps offer share-with-vet links.