Growing Cannabis at Home in Washington

Growing Cannabis at Home in Washington

In Washington State, recreational cannabis has been legal for over a decade—but growing it at home is still restricted. Only registered medical marijuana patients are allowed to cultivate cannabis at home, and even then, it must be done carefully and in full compliance with state law.

If you qualify, home cultivation can be a powerful way to take charge of your medicine. Whether you’re growing in a closet, a garage, or a backyard greenhouse, your success depends on staying within the law, setting up the right environment, and tending your plants with care.

Click here for the most current home cultivation guidelines from Washington’s Department of Health.


Washington Law: What You Need To Know Before You Grow

Only medical marijuana patients registered in the state’s Medical Marijuana Authorization Database may legally grow cannabis at home.

Here are the legal basics:

Age Requirement: Patients must be 18 or older to grow. Minors may qualify for medical use with a designated caregiver, but only adults can cultivate.

Plant Count (Medical):

  • Registered patients may grow up to 6 plants for personal medical use.

  • A healthcare provider may authorize up to 15 plants if medically necessary.

  • Patients may possess up to 8 ounces of usable cannabis from their homegrow (or more, if authorized).

Plant Count (Recreational):

  • Home growing is not legal for recreational users. Any unlicensed cultivation, even a single plant, is a criminal offense.

Growing Location:

  • All cannabis must be grown in the patient’s private residence.

  • Plants must be not visible to the public and grown in an enclosed, secure space (a locked room, tent, or greenhouse is ideal).

  • Outdoor growing is allowed only if fully fenced, locked, and not visible from the street or neighboring properties.

Storage Rules:
Harvested cannabis must be kept secure, labeled, and used only by the registered patient. It cannot be shared or sold.

Caregiver Grows:
Designated providers may grow on behalf of a patient, but they must also be entered in the state database and follow the same limits.


Indoor Growing in Washington

Washington’s wet winters and unpredictable weather make indoor growing the most reliable option for many medical patients.

Build a Compliant Grow Setup

Make sure your grow space is:

  • Locked and enclosed

  • Located inside your residence

  • Not visible from outside

Popular options:

  • Grow tents in spare bedrooms

  • Converted closets with ventilation

  • Standalone grow cabinets

Light It Right

Choose full-spectrum lighting for healthy plants:

  • LEDs: Low heat, low energy, full control

  • HID (MH/HPS): High-intensity for bigger grows

  • Fluorescents: Budget-friendly for early veg or clones

Stick to these light cycles:

  • Veg: 18 hours on / 6 off

  • Flower: 12 hours on / 12 off

Use timers to automate your lighting schedule.

Manage the Environment

Washington’s indoor humidity can climb, especially in basements or poorly ventilated areas:

  • Temperature: 70–85°F

  • Humidity: 50–60% in veg, 40–50% in flower

  • Use:

    • Inline fans & carbon filters

    • Dehumidifiers during flowering

    • Hygrometers and thermometers

Pick a Growing Medium

Most homegrowers in Washington use:

  • Organic soil mixes with compost and perlite

  • Fabric pots for airflow and drainage

  • Hydroponics for more advanced growers (but watch for humidity spikes)

Nutrients & pH

Cannabis needs different nutrients depending on the stage:

  • Veg: Nitrogen-heavy formulas

  • Flower: Phosphorus and potassium-rich

  • Keep soil pH between 6.0–7.0


Outdoor Growing in Washington

Outdoor growing is legal for medical patients only, but you must be extremely cautious about visibility and security.

Legal Compliance

Your outdoor grow must be:

  • At your private residence

  • Fully enclosed, locked, and invisible to the public

  • Not accessible by pets, kids, or unauthorized adults

Weather Challenges

Washington’s Pacific Northwest climate is beautiful—but tricky for cannabis:

  • Rain & humidity: Watch for mold and mildew

  • Cool nights: Choose fast-finishing, mold-resistant strains

  • Sunlight: Ensure at least 6 hours of direct sun per day

Use greenhouses or hoop houses to extend the season and protect buds from early fall rain.

Outdoor Pest Control

Expect to encounter:

  • Slugs and snails

  • Aphids

  • Caterpillars

  • Powdery mildew

Combat pests with:

  • Neem oil or insecticidal soap

  • BT spray for caterpillars

  • Good airflow and spacing to reduce mold risks


What You’ll Need To Start Your Grow in Washington

Here’s your gear checklist for a successful homegrow:

Washington Medical Marijuana Authorization (registered)
Grow Tent or Secure Room
LED Grow Lights or HID Setup
Fabric Pots and Quality Soil
Ventilation System and Carbon Filter
Thermometer and Hygrometer
Cannabis-Specific Nutrients
Timers for Light Cycles
pH Tester and Adjusters
Plant Supports (cages or netting)


Best Strains for Washington Growers

Due to cool temps and high humidity, go for mold-resistant, fast-finishing strains:


Troubleshooting Common Washington Grow Problems

Problem: Mold or Bud Rot
Cause: High humidity, poor airflow
Fix: Prune dense foliage, increase air circulation, and use dehumidifiers

Problem: Yellowing Leaves
Cause: Nutrient deficiency or improper pH
Fix: Test soil and adjust pH; feed with appropriate nutrients

Problem: Stunted Growth
Cause: Cold nights or overwatering
Fix: Use heating mats or bring plants indoors; let soil dry between waterings

Problem: Stretchy Plants
Cause: Inadequate lighting
Fix: Lower lights or increase intensity

Problem: Insect Damage
Cause: Outdoor pests or poor sanitation
Fix: Use organic pest control and inspect plants regularly


Your Washington Grow Starts Here

For registered medical patients in Washington, home cultivation is not only legal—it’s a path to self-sufficiency, wellness, and a deeper connection to your medicine. With the right tools, knowledge, and respect for state law, you can grow confidently and cultivate high-quality cannabis right from home.

HomeGrow Helpline is here to support Washington growers every step of the way—from silly questions to troubleshooting your first harvest.

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