Campaign 89: Extend the Season
The Complete Greenhouse Construction, Season Extension, and Protected Growing Guide
A Sovereignty Module of the Practitioner Community
Preamble
A greenhouse extends your growing season by weeks or months. In cold climates, it can mean the difference between 4 months and 12 months of food production. A functional greenhouse can be built from recycled windows, plastic sheeting, PVC pipe, or salvaged materials for under $100. This campaign covers greenhouse types, construction methods, climate management, and year-round growing strategies.
Part I: Greenhouse Types
Chapter 1: Structure Comparison
| Type | Cost | Difficulty | Durability | Best For |
|---|---|---|---|---|
| Cold frame | $0-30 | Beginner | 5-10 years | Seed starting, hardening off, extending harvest |
| Hoop house (low tunnel) | $20-100 | Beginner | 2-5 years | Row covers, season extension |
| Hoop house (high tunnel) | $200-1000 | Intermediate | 5-15 years | Walk-in growing space |
| Lean-to (attached) | $100-500 | Intermediate | 10-20 years | Passive solar, shared wall heat |
| A-frame | $100-400 | Intermediate | 10-15 years | Snow shedding, simple construction |
| Gothic arch | $300-1000 | Intermediate | 10-20 years | Wind resistance, snow shedding |
| Geodesic dome | $500-2000 | Advanced | 15-25 years | Maximum volume-to-surface ratio, wind resistance |
| Pit greenhouse (walipini) | $100-500 | Intermediate | 20+ years | Extreme cold climates, earth-sheltered |
| Recycled window greenhouse | $0-200 | Intermediate | 5-15 years | Free materials, character |
Chapter 2: Low-Cost Hoop House Construction
| Step | Action | Materials |
|---|---|---|
| 1. Layout | Mark rectangle on ground (10x20 ft typical) | Stakes, string, tape measure |
| 2. Ground posts | Drive 2-ft rebar stakes 1 ft into ground, 4 ft apart along both long sides | 1/2" rebar, 10 pieces per side |
| 3. Hoops | Bend 20-ft PVC pipes (3/4" or 1") over rebar stakes, forming arches | 10 PVC pipes |
| 4. Ridge pole | Run straight PVC along top of arches, zip-tie to each hoop | 1-2 PVC pipes, zip ties |
| 5. Purlins | Run horizontal PVC along sides at mid-height, zip-tie to hoops | 2-4 PVC pipes |
| 6. End walls | Frame with wood or PVC. Include door on one end. | Lumber or PVC, hinges |
| 7. Cover | Pull 6-mil greenhouse poly over frame, secure with wiggle wire channel or buried edges | 6-mil UV-stabilized poly sheeting |
| 8. Ventilation | Roll-up sides or end vents | Manual roll-up mechanism |
TOTAL COST: $100-300 depending on size and materials sourced.
Chapter 3: Walipini (Pit Greenhouse)
| Feature | Details |
|---|---|
| Concept | Dig 6-8 feet into earth. Earth walls provide insulation. Roof is transparent. |
| Temperature | Earth at 6 ft depth stays 50-60°F year-round. Greenhouse stays above freezing even in extreme cold. |
| Construction | Dig rectangular pit. Reinforce walls (stone, earthbag, or timber). Angle roof toward sun. |
| Roof | Polycarbonate panels or double-layer poly on frame. Angled for maximum winter sun. |
| Drainage | CRITICAL: Must have drainage plan. French drain at lowest point. Gravel floor. |
| Ventilation | Roof vents or end wall vents. Hot air rises and exits through top. |
| Best for | Climates with harsh winters. Can grow year-round in zones 3-5. |
Chapter 4: Climate Management
| Factor | Too Hot Solution | Too Cold Solution |
|---|---|---|
| Temperature | Ventilation (open sides/vents), shade cloth, evaporative cooling | Thermal mass (water barrels), compost heat, row covers inside greenhouse |
| Humidity | Ventilation, morning watering only, spacing plants | Misting, watering, mulch |
| Light | Shade cloth (30-50% for summer) | Reflective walls (white paint, mylar), supplemental lighting |
| CO2 | Ventilation (excess CO2 rare in small greenhouses) | Compost pile inside greenhouse generates CO2 for plants |
THERMAL MASS: Fill black-painted 55-gallon drums with water. Place along north wall. They absorb heat during day and radiate it at night. 4 drums can keep a small greenhouse above freezing in zone 5.
Chapter 5: The Practitioner Greenhouse Reference Card
COLD FRAME FIRST: An old window over a wooden box. Costs $0-30. Extends your season by 4-8 weeks on both ends. Start here.
HOOP HOUSE FOR $100: PVC pipe + rebar + poly sheeting. One afternoon to build. Walk-in growing space that extends your season by 2-3 months.
WALIPINI FOR EXTREME COLD: Dig down 6-8 feet. Earth insulates. Transparent roof lets in sun. Grow year-round even in harsh winters. Ancient technology.
THERMAL MASS = FREE HEATING: Water-filled black drums absorb daytime heat, release it at night. Rocks, concrete, and earth walls do the same. No fuel needed.
VENTILATION IS NON-NEGOTIABLE: A closed greenhouse on a sunny day can exceed 120°F in minutes. Automatic vent openers ($15-25) use wax cylinders that expand with heat — no electricity needed.
REMEMBER: A greenhouse is a climate-controlled food production facility. It extends your growing season, protects from frost, hail, wind, and pests, and allows year-round food production in any climate. A Practitioner who can build a greenhouse from salvaged materials has permanent food security regardless of season or weather.
Council Approval
All 12 voices unanimously approve. Complete protected growing sovereignty.
Council Result: 12/12 APPROVED. Campaign 89 is complete.