How Many Plants Can You Grow? The ACMPR Plant Count Formula Explained
It is the first question almost every patient asks about growing their own medical cannabis: how many plants am I allowed?
You do not choose the number. It is calculated from your authorised daily amount using a formula set out in the Cannabis Regulations. Here is the actual formula, worked examples at realistic daily amounts, and the reason the biggest number a calculator produces is rarely the number you want.
The formula
Section 325 of the Cannabis Regulations sets the maximum number of plants. In every version of the calculation, A is your authorised daily quantity of dried cannabis in grams, taken from your medical document.
| Where you grow | The calculation | In practice |
|---|---|---|
| Indoors only | (A x 365) divided by 90, then multiplied by 1.2 | About 4.87 plants for every gram per day |
| Outdoors only | (A x 365) divided by 250, then multiplied by 1.3 | About 1.9 plants for every gram per day |
| Both | Indoor portion: (A x 182.5) divided by 60, then x 1.2 Outdoor portion: (A x 182.5) divided by 250, then x 1.3 | About 3.65 indoor plus 0.95 outdoor, per gram per day |
The regulation assumes an expected yield of 30 grams per plant indoors and 250 grams per plant outdoors, with three indoor harvests a year against one outdoor harvest. If the result is not a whole number, it is rounded up.
Worked examples
These are the numbers the formula produces at daily amounts patients are actually authorised for:
| Daily amount | Indoor only | Outdoor only | Both |
|---|---|---|---|
| 1 gram per day | 5 plants | 2 plants | 4 indoor + 1 outdoor |
| 2 grams per day | 10 plants | 4 plants | 8 indoor + 2 outdoor |
| 3 grams per day | 15 plants | 6 plants | 11 indoor + 3 outdoor |
| 5 grams per day | 25 plants | 10 plants | 19 indoor + 5 outdoor |
| 10 grams per day | 49 plants | 19 plants | 37 indoor + 10 outdoor |
Health Canada publishes its own calculator, and your registration certificate will state the final figure along with how much dried cannabis you may store, your approved production site and your approved storage site.
Why the biggest number is not the best number
This is where the arithmetic stops being the important part.
Health Canada has noted that most people using cannabis for medical purposes in Canada use between 1 and 3 grams of dried cannabis a day. Among personal and designated production registrations, roughly 72 percent fall in the 10 to 24 grams per day range, and around 3 percent are for 25 grams a day or more, which translates to a capacity of more than 100 plants indoors.
That gap is why registrations are now being refused and revoked in large numbers. As of 31 March 2025, Health Canada had refused or revoked more than 4,100 medical cannabis registrations, around 3,400 of them on public health and public safety grounds. Our article on why Health Canada is revoking ACMPR registrations covers what is driving it.
Run the formula backwards and the point becomes obvious. A plant count in the hundreds requires a daily amount in the tens of grams, and a daily amount in the tens of grams is exactly what Health Canada now questions. A registration built on an amount your practitioner cannot defend is not an asset. It is a file waiting to be reviewed.
What actually determines your daily amount
Your authorised daily amount is a clinical decision made by a physician or nurse practitioner, based on your condition, what you have already tried and how you respond. It is not a number you request, and no clinic can promise you a figure before an assessment.
Our complete guide to cannabis prescriptions in Canada explains how the assessment works, and the 2026 ACMPR requirements checklist lists everything the application needs.
Practical considerations before you commit
- Space and equipment. Twenty-five indoor plants is a serious setup, not a corner of a spare room. Factor in lighting, ventilation, electricity and your time.
- Storage limits. Your certificate states how much dried cannabis you may store, which is a separate figure from your plant count.
- Coverage. Neither WSIB nor Veterans Affairs Canada reimburses home-grown cannabis. If you expect to qualify for coverage, growing may cost you more than it saves. Our breakdown of what medical cannabis costs in 2026 compares the routes.
- Security and site rules. Covered in our guide to the ACMPR requirements.
Want to know what plant count your situation would realistically support? Start with a clinical assessment.
Start Your ApplicationFrequently asked questions
How many plants can I grow per gram per day?
Roughly 4.87 plants per gram per day if you grow indoors, or about 1.9 per gram per day outdoors. The figure is rounded up to the next whole number.
Who decides my daily amount?
A physician or nurse practitioner, based on your condition and treatment history. It is a clinical decision, not something you choose or request.
Can I change where I grow after registering?
Your certificate names your approved production and storage sites, and whether you grow indoors, outdoors or both. Changing any of those requires updating your registration.
Is a higher plant count better?
No. A high plant count requires a high daily amount, and those are the registrations Health Canada is currently scrutinising most closely. A modest, clinically defensible amount is far more likely to be approved and to stay approved.
How much dried cannabis can I store?
Your registration certificate states a separate storage limit alongside your plant count.
Can I start growing as soon as I apply?
No. You must wait until Health Canada issues your registration certificate. While production gets established you can obtain starting materials and an interim supply from a licensed seller.
Next step
The plant count follows the clinical assessment, not the other way round. Apply now, read the full ACMPR requirements checklist, or contact our team with questions.
This article is for general information only and is not legal or medical advice. The formula described is set out in the Cannabis Regulations and may change. Confirm current requirements with Health Canada before applying.