Perpetual Harvest Calculator
Calculate exactly how many plants you need for continuous harvests
Different strains have different veg and flowering periods. For precise planning with multiple strains, try Plantegia
What is Perpetual Harvest?
Perpetual harvest is a growing method where you stagger plant starts so you harvest fresh plants every few weeks instead of all at once. By maintaining plants at different growth stages simultaneously, you create a continuous supply without long gaps between harvests.
Quick Reference: Common Setups
| Flowering Time | Harvest Every | Plants in Flower | Plants in Veg* | Total |
|---|---|---|---|---|
| 8 weeks | 1 week | 8 | 4 | 12 |
| 8 weeks | 2 weeks | 4 | 2 | 6 |
| 9 weeks | 2 weeks | 5 | 2 | 7 |
| 10 weeks | 2 weeks | 5 | 3 | 8 |
| 10 weeks | 3 weeks | 4 | 2 | 6 |
*Assuming 4-week veg period. Adjust based on your grow style.
How to Use This Calculator
Enter your strain's flowering time, desired veg period, and how often you want to harvest. The calculator shows exactly how many plants you need in veg and flower to maintain continuous harvests.
Key Inputs Explained
- Flowering Period: How long your strain takes to flower. Check seed bank info — typically 8-10 weeks for most strains.
- Veg Period: How long you keep plants in vegetative growth. Longer veg = bigger plants but more space needed.
- Harvest Frequency: How often you want to harvest. Every 2 weeks is common and manageable for most setups.
The Two-Tent Setup
Most perpetual growers use two separate spaces: a veg area (18/6 light) and a flower area (12/12 light). Plants move from veg to flower when ready. This separation is essential because flowering plants need uninterrupted darkness.
Example Calculation
With an 8-week flowering strain and harvesting every 2 weeks, you need 4 plants in flower at different stages. Add 2 plants in veg (4-week veg period), and you need 6 total plants running at all times.
Tips for Success
- Start with fewer plants than calculated while you learn the rhythm
- Use the same strain initially — mixing flowering times complicates scheduling
- Label plants with start dates to track where each one is in the cycle
- Consider cloning for consistency — seeds can vary in flowering time
Frequently Asked Questions
How many plants do I need for perpetual harvest?
It depends on flowering time and harvest frequency. For an 8-week strain harvesting every 2 weeks, you need 6 plants total (4 flowering + 2 veg). Use the calculator above with your specific parameters.
Can I do perpetual harvest with one tent?
It's difficult because veg and flower require different light schedules (18/6 vs 12/12). Some growers use autoflowers in a single tent, but a two-tent setup gives you much more control.
What's the best harvest frequency for beginners?
Every 2 weeks is ideal for most home growers. Weekly harvests require more plants and management. Monthly harvests mean longer waits between fresh supply.
Do I need to start all plants at once?
No — you stagger starts to match your harvest frequency. If harvesting every 2 weeks, start a new plant every 2 weeks. The calculator shows this timing.
Plan Your Full Rotation
This calculator tells you how many plants you need. Plantegia shows you exactly when to start, move, and harvest each one — with a visual timeline across all your grow spaces.
Try Plantegia Free