Winterization Post-Season Guide
Get your site winter-ready before the wet season arrives
Winterization protects your land, your water and your permit. Here is what the State Water Board expects from every cannabis cultivator, every year.
The Winterization Checklist
Complete these every year before the winter period starts. The Mitigation Report in your Site Management Plan lists additional steps specific to your property.
Drainage & roads
- Clear culvert inlets, outlets and trash racks of debris and sediment
- Check outlets for erosion undermining the culvert
- Repair wheel ruts, rills and gullies on road surfaces
- Block seasonal access roads to motor vehicles until the winter period ends
Secure materials
- Store fertilizers, pesticides and petroleum products outside riparian setbacks, covered, with secondary containment
- Secure anything synthetic that wind or rain could carry away
- Collect trash and take it to a waste transfer facility
Water & facilities
- Seal water tanks and bladders so wildlife cannot enter or become trapped
- Drain or insulate water lines where temperatures drop below freezing
- Remove chemical toilets, or service them and leave them unused
Stop Erosion Before it Starts
Bare soil is the biggest winter risk. The goal is to keep every bit of sediment out of Waters of the State.
Cover and stabilize
- Seed exposed soil with native, non-invasive grasses and cover with weed-free straw mulch
- Apply straw mulch at about two tons per acre, secured where site conditions call for it
- Stabilize disturbed areas and construction entrances and exits
- Seed and mulch fill pads and fill slopes right away
Capture sediment
- Install silt fences or straw wattles along the toe, face and grade breaks of exposed slopes
- Maintain every sediment control feature through the winter
- Surface footpaths and secondary roads used in wet weather
- Have permanent controls designed and built by qualified professionals
Soil, spoils & spent growing medium
Stored soil and spent media can leach nutrients and sediment into groundwater and streams if left uncovered.
Cover it
Keep potting soil and amendments covered and secured when not in use. Cover and berm any stockpile that won't be used within 48 hours.
Contain it
Store spent growth medium under plastic sheeting or in watertight dumpsters, away from the riparian setback and waters of the state.
Dispose or reuse properly
Send spent medium to an authorized landfill, or reuse it in garden beds or on a stable, revegetated surface with erosion controls.
Close out your Metrc records in advance
Everything on your site should be accounted for and wrapped up in your track-and-trace records before you walk away, not after. Getting entries current now means you aren’t scrambling or leaving gaps while you’re out of town.
Record it on time
24 hrs · 72 hrs
Most activity, including receipt, destruction or disposal, packaging, lab testing, and sales or donations, must be recorded in track and trace within 24 hours.
Cultivation milestones (planting, moving to canopy, flowering, tagging, plant destruction, harvesting) must be entered within three calendar days (72 hours).
When in doubt, enter it the same day.
Document destruction & disposal
Who · Why · How
For any destruction or disposal, the entry's notes must include who did it, why and how.
Harvested plants still drying, curing or being trimmed don't need tags, but they must still be recorded.
Reconcile your inventory
Every 30 days
On-site inventory must be reconciled with your track-and-trace records at least once every 30 days.
Do a final count before you leave, and include a reason for any package adjustment that changes a recorded quantity.
Record it on time
Most activity, including receipt, destruction or disposal, packaging, lab testing and sales or donations must be recorded in track and trace within 24 hours.
Cultivation milestones (planting, moving to canopy, flowering, tagging, plant destruction, harvesting) must be entered within three calendar days (72 hours).
When in doubt, enter it the same day.
Document destruction & disposal
For any destruction or disposal, the entry's notes must include who did it, why and how.
Harvested plants still drying, curing or being trimmed don't need tags, although they must still be recorded.
Reconcile your inventory
On-site inventory must be reconciled with your track-and-trace records at least once every 30 days.
Do a final count before you leave, and include a reason for any package adjustment that changes a recorded quantity.
- Harvests entered, with all batches and weights recorded
- All plant waste, trim and spent material recorded and disposed of properly
- Unused plant and package tags accounted for
- Remaining inventory counted, matched to Metrc and stored securely
- Transfers, sales, donations and lab results entered and complete
- Unused plant and package tags accounted for
- Nothing left pending that someone else would need to finish while you're away
Check the details for your license.
Time limits come from California's track-and-trace regulations (4 CCR §15049) and the Department of Cannabis Control's cultivator self-inspection checklist, which says it is not an exhaustive list. Confirm the rules for your license type with the Department (enroll@cannabis.ca.gov, 1-844-612-2322) or your Flowra advisor.
Heading out of state? Your site’s obligations stay
Many cultivators leave the property or the state once harvest wraps. Your winterization requirements don’t pause when you do. The rules apply to the site for the entire winter period, whether or not anyone is there.
Finish before you go
- Complete drainage work, seeding, mulching and sediment controls while you're still on site
- Remove or service chemical toilets and seal tanks and bladders
- Drain or insulate water lines in areas that may freeze
- Block seasonal access roads and store all materials with adequate coverage and containment
- Bring your Metrc records fully up to date with nothing left to reconcile
Plan for what you can't watch
- Sediment controls must keep working all winter, so someone needs to be able to check and maintain them after storms
- Heavy equipment is off-limits all winter, other than emergency repairs under an enforcement order, so a problem you can't fix remotely needs to be prevented now
- Check your Site Management Plan for site-specific winter measures before you leave