The short answer

There is no federal number. Cannabis is still illegal under federal law, so the plant count that matters is the one written into your state's rules. In states that allow home grow, the limit is usually 2 to 12 plants per household, and a handful of legal states allow zero at home.

Someone in Michigan can keep 12 plants. Someone in Virginia can keep 4. Someone in New Jersey or Pennsylvania can keep none, medical card or not. Same country, very different answers.

Why the number changes at the state line

Federal law has not legalized cannabis in any form. It remains a Schedule I controlled substance, so cultivation without federal authorization is a federal offense even where a state says it is fine. State legalization is essentially a truce: states decline to prosecute their own residents, and federal prosecutors have mostly left small personal grows alone.

Because there is no federal framework, every state writes its own rules. That is why plant limits, who qualifies as a patient, and whether you can grow outdoors at all can change when you cross a county line.

Common limits in states that allow home grow

These numbers shift. Lawmakers adjust caps, courts strike down residency requirements, and ballot measures add or remove home grow. Treat any list, including this one, as a starting point and confirm your current statute.

Per-person caps vs household caps

Read this part twice, because it is where people get cited. Some states count plants per adult and then stack a household ceiling on top. New York lets each adult grow 6, but no household may exceed 12, and only some may be mature at once. Other states cap the house regardless of headcount. Colorado's 12-plant residence limit applies in a house with four adults just as it does in a house with one.

Medical patients usually get more room

Most medical programs set a higher count for registered patients. Hawaii allows 10 plants with a valid registration. Washington lets qualified patients grow up to 6, and up to 15 with a practitioner's authorization. Colorado patients on an extended plant count can exceed 12. Recreation-only states rarely offer that flexibility, so a medical card still matters if you grow for a condition.

What legally counts as a plant

This trips people up more than the cap itself. Some states count every plant from the moment it sprouts. Others count only flowering plants and treat seedlings as exempt. Missouri counts flowering plants. Maine separates mature, immature, and seedlings. Ohio's statute distinguishes flowering from non-flowering. If you run clones or keep a mother plant, find out how your state classifies it. A mother plant in a veg tent may or may not eat into your allotment.

Things that quietly lower your limit

Where to check before you plant

Start with your state's cannabis regulatory agency, the one that licenses dispensaries. Its site carries the statute or a plain-language summary of home cultivation rules. Then check your county and city codes for a zoning or occupancy ordinance that touches growing at home. Then read your lease. If you are a medical patient, confirm your registration is active and check whether your plant count is printed on the card or set by statute.

One more thing: the plant count is a ceiling, not a goal. Going over by a few plants is a ticket in some states and a criminal charge in others. If you live near the line, tag your plants, date your notes, keep photos, and save the statute you are relying on.