Season Extension.


'Shoulder season extension tunnels for regenerative soil systems.'

(Portable hothouses, Cocoon tunnels, Caterpillar tunnels, Season extension tunnels)

Cocoon Tunnels aka Caterpillar Tunnels as they are often referred have been around for a few decades, finding a place in the fringes of small growers systems in varying forms of DYI or more often than not, clumsy kit forms. This earlier tangent has completely shifted to the very real need of professional micro-farmers.

More recently the groundswell in regenerative, soil focused micro-farming has led to rethinking the need for good quality, professional use Cocoon Tunnels that are economically justifiable.

Crop rotation is of critical importance for successfully regenerating living soil, by using a modular/standardised bed block system we can incorporate standardised season extension tunnels into the design. This allows a number of benefits to the regenerative farmer.

  • Timed cover of crop/bed block for effective season extension.

  • Timed removal of early season cover, shading mid summer, late season cover.

  • Increased unheated hot house area for specialty hybrids, eggplant, tomato, capsicum and cucumbers to name a few.

  • regenerative soil management.

  • Greater versalitility in planning, ability to move across zones or blocks.

  • Seasonal adaptability, a variety of different grade covers can be used, shade cloth or poly films.

Typical design.

  • Span,the Cocoon Tunnel kits from ActiveVista span four permabeds, about 5metres.

  • Height, the eight metre x 35mm hoop arcs tube steel peak at 2.4m and is semi circular in gradient.

  • Length between end hoops, although lengths could easily be modified ActiveVista Cocoon Tunnels are either 15 metres (50 foot) or 30 metres (100 foot).

  • End 'triangular tie off' lengths, these can be modified slightly and range from 3 to 4 metres from the last hoop to a star picket, angled backward and centered perpendicular to the end hoop.

  • The beds need spare area at the bed ends ranging totaling 6 to 8 metres overall, this can be dealt with by losing a bit of end bed while still growing within the tapered area.

  • Side walls, typically these can be lifted and will allow good air flow across both sides length-ways.

  • Semi-permanent stays, the hoops sit over 100cm x 16mm rebar inserted about 400 mm into the earth. A 'Jack Jaw' star picket remover will make easy removal of these, or a refashioned diamond jack.

  • Centre purlin, in the basic and effective form the purlin is a nylon strap, tied off to the star pickets at either end. Snow protection can be added by using the static tube steel purlin option.


There is a variety of Cocoon Tunnel options available from making your own from sourced components to buying a kit.

Pros and cons.

  • If not set up correctly they will be problematic.

  • Can be set up quickly by few people on a still day.

  • Although sourcing your own may save you dollars, it may take a whole lot more time and headspace away from the matter at hand, growing and selling the food.

  • It may be possible to DYI with the some easily sourced affordable parts such as a hoop bender, rope, carabiners, purlin strap, 150um film, rebar, again you will need to cut a bunch to length of about 1000mm.