# 12/12 from clone or seed: more harvests a year, and why the founder is a huge fan

> Flowering clones or seedlings on 12/12 straight away skips most of the veg, so one space turns over more harvests a year: about 4.5 harvests from a single room with 12/12 from clone, against about 3.3 with 4 weeks of veg and 2.7 with 8 weeks in the same space. Each harvest is smaller per plant, but packing in more plants (sea of green) raises yield per area. The founder is a huge fan and says that with good clones, dialled in, 4+ oz per square foot is not unheard of (field experience, well above published research yields).

- Canonical: https://genetixbay.com/knowledge/training/12-12-from-clone-or-seed.html
- Category: Training · Level: Intermediate
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Stage: Veg, Flower · Systems: Any system
- Updated: 2026-11-02 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**Does [12/12](https://genetixbay.com/knowledge/glossary/12-12.md) from clone yield more per year?** Usually, from the same space. With about 10–11 weeks from flip to harvest and a week to turn the room around, 12/12 from clone gives roughly 4.5 harvests a year, against about 3.3 with 4 weeks of veg and 2.7 with 8 weeks in the same room. Each harvest is smaller per plant, so you plant more densely ([sea of green](https://genetixbay.com/knowledge/glossary/sog.md)).

**How much can 12/12 from clone yield per square foot?** It depends heavily on cultivar, light and skill. The founder says that with good clones, dialled in, 4 or more ounces per square foot (about 1,200 [g/m²](https://genetixbay.com/knowledge/glossary/yield.md)) is not unheard of (field experience). That's well above published research yields, which topped out around 0.5 kg/m² in one light trial and 0.5–0.75 kg/m² in well-run research rooms, so treat it as a top-end result.

**Can you flower a seed 12/12 from the start?** Yes, but it won't flower straight away. A [photoperiod](https://genetixbay.com/knowledge/glossary/photoperiod.md) [seedling](https://genetixbay.com/knowledge/glossary/seedling.md) has to mature first, forming its first flowers at around the 7th node, typically after 3–5 weeks, so the run takes roughly 3 months. You'll also want feminised seed, since regular seed gives males you must find and remove. Clones from a mature mother skip that wait.

**Why do 12/12 runs take longer than the breeder says?** Because the clock starts at the flip, and there's a transition of about 10–14 days before flowering really begins. Breeder flowering times often count from first pistils, not from the flip. Plan a 12/12 run as breeder time plus about 2 weeks, and log both days since flip and days of flower.

**What do I need for 12/12 from clone?** A steady supply of healthy, rooted clones from a mother or nursery space, a flower room planted densely (sea of green), strong even light, and a turnaround routine so the room is never empty. The nursery is what makes it work: while one batch flowers, the next is rooting, so the flower room goes straight from harvest to the next batch.

**Short answer, in plain words.** Most growers spend weeks growing big plants before they flip to flower. **12/12 from clone** skips most of that: rooted clones go straight into the flower room. Each plant is smaller, so you plant more of them, and the room finishes a crop and starts the next one sooner. Over a year that's about **4.5 harvests from one room instead of about 3** (arithmetic below). The founder is **a huge fan**: with good clones, dialled in, **4+ oz per square foot is "not unheard of"** (founder's field experience) [5]. That's well above published research yields, so read it as a top-end result, not a promise.

> **Greenleaf says:** Count harvests per year, not grams per plant. A small plant that's finished is worth more than a big one still in veg.

## How many harvests a year?

Count from the flower room's point of view. With **about 10–11 weeks from flip to harvest** (a typical 8–9 week flowering time plus the 10–14 day transition after the flip; see [flip-to-flower transition](https://genetixbay.com/knowledge/environment/flip-to-flower-transition.md)) and **a week to clean and replant**:

| Approach (one space does everything) | Weeks per cycle | Harvests per year |
|---|---|---|
| 12/12 from rooted clone | 10.5 + 1 = 11.5 | ~4.5 |
| 4 weeks of veg, then flower | 4 + 10.5 + 1 = 15.5 | ~3.4 |
| 8 weeks of veg, then flower | 8 + 10.5 + 1 = 19.5 | ~2.7 |
| 12/12 from seed (seedling must mature first) | ~13 + 1 = 14 | ~3.7 |

Harvests per year = 52 ÷ weeks per cycle. A separate veg or nursery space lets any approach keep the flower room flowering non-stop; 12/12 from clone simply needs the least veg space to do it.

**Chart: Harvests a year from one space.** Flowering rooted clones straight away gives about 4.5 harvests a year from one space; 12/12 from seed about 3.7; 4 weeks of veg about 3.4; 8 weeks of veg about 2.7.

| Approach | Harvests per year (harvests) |
|---|---|
| 12/12 from clone | 4.5 |
| 12/12 from seed | 3.7 |
| 4 weeks veg | 3.4 |
| 8 weeks veg | 2.7 |

Source: 52 ÷ weeks per cycle, table above; transition from the flip-to-flower article.

## Yield per year, not per harvest

Each 12/12 plant yields less, so the trick is **density**: in a controlled study, higher [planting density](https://genetixbay.com/knowledge/glossary/plant-density.md) increased yield per area, at some cost to [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md) uniformity between plants [2]. Across many studies, yield per area is driven mostly by light and plant density [3][4].

Illustrative yield per square foot per year (multiply per-harvest yield by harvests):

| Per harvest | × harvests | Per year |
|---|---|---|
| 2 oz/ft² after 8 weeks of veg | × 2.7 | ~5.4 oz/ft² |
| 1.5 oz/ft² from 12/12 clones | × 4.5 | ~6.8 oz/ft² |
| 4 oz/ft² from good clones, dialled in (founder's field experience) [5] | × 4.5 | ~18 oz/ft² |

**Honest note on the 4 oz/ft² figure.** 4 oz/ft² is about **1,220 g/m²**. In the best published light trial, yield topped out at 519 g/m² at 1,800 [µmol/m²/s](https://genetixbay.com/knowledge/glossary/ppfd.md) [4], and our [grams per watt](https://genetixbay.com/knowledge/answers/grams-per-watt.md) answer puts well-run research rooms at about 500–750 g/m². The founder's figure is well above that range; it's a field result from [elite clones](https://genetixbay.com/knowledge/glossary/elite-cut.md) in a dialled-in room, and a great candidate for documented GenetixBay grow journals.

**12/12 from clone, by the numbers.** ~4.5: Harvests a year from one space; ~2.7: With 8 weeks of veg in the same space; 4+ oz/ft²: Dialled-in clone runs, founder's field experience (≈ 1,220 g/m², above published yields). Source: Tables above; trial yields [4]; founder [5].

## Clone or seed?

**12/12 from clone vs 12/12 from seed**
- **From clone** (Cut from a mature mother)
  - Pro: Can start flowering soon after rooting
  - Pro: Every plant the same: [even canopy](https://genetixbay.com/knowledge/glossary/even-canopy.md)
  - Pro: Known sex and known cultivar
  - Con: Needs a mother or nursery space
  - Con: Pests and diseases travel with clones
- **From seed** (Photoperiod seedling)
  - Pro: No mother needed
  - Pro: Clean start
  - Con: Must mature first: first flowers around the 7th node, after 3–5 weeks
  - Con: Regular seed brings males to remove
  - Con: Uneven heights between [phenotypes](https://genetixbay.com/knowledge/glossary/phenotype.md)

Seedlings go through a juvenile phase before they can flower, forming their first flowers at around the 7th node [1] (see [can I flower 12/12 from seed?](https://genetixbay.com/knowledge/answers/12-12-from-seed.md)).

## What "dialled in" means

1. **Good clones:** healthy, vigorous, rooted, pest-free, from a proven cut.
2. **Density:** a sea of green, many small plants (see [sea of green](https://genetixbay.com/knowledge/training/sog.md)).
3. **Strong, even light:** see [more light, more yield](https://genetixbay.com/knowledge/environment/more-light-more-yield.md).
4. **A nursery rhythm:** the next batch rooting while this one flowers, so the room is never empty.
5. **Climate and feeding** that keep up with fast-flowering plants.

## Common mistakes

- Comparing grams per plant instead of grams per square foot per year.
- Flipping seedlings 12/12 and expecting flowers in week one.
- Running 12/12 from clone without a clone supply, so the room sits empty.
- Planting too sparsely for small plants.

## Sources

1. Spitzer-Rimon B, Shafran-Tomer H, Gottlieb GH, et al. 2022. Non-photoperiodic transition of female cannabis seedlings from juvenile to adult reproductive stage. Plant Reproduction 35(4):265-277. https://doi.org/10.1007/s00497-022-00449-0
2. Danziger N, Bernstein N. 2022. Too dense or not too dense: higher planting density reduces cannabinoid uniformity but increases yield/area in drug-type medical cannabis. Frontiers in Plant Science 13:713481. https://doi.org/10.3389/fpls.2022.713481
3. Backer R, Schwinghamer T, Rosenbaum P, et al. 2019. Closing the yield gap for cannabis: a meta-analysis of factors determining cannabis yield. Frontiers in Plant Science 10:495. https://doi.org/10.3389/fpls.2019.00495
4. Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020
5. GenetixBay founder. Field experience (first-hand account; GenetixBay house position).