Vern Nelson: Selecting durable posts for garden structures
The Oregonian, Saturday, March 10, 2012
By Vern Nelson
Here's the link to the original article.
The best kitchen gardens employ structures -- trellises, espaliers and many other types -- to make the most of available space and to help the garden be as beautiful as it is productive. Posts for garden structures are available in many sizes and materials. Each wood used has advantages and disadvantages.
My favorite posts are made of juniper, which contains aromatic oils that make the wood resist rot. Juniper is beautiful, sustainably grown in eastern Oregon and locally available.
Juniper posts are available as 8-foot-long 4-by-4s and 8-foot-long 6-by-6s and are similar in price to cedar. Planks of various sizes are also available. Lengths of 10 feet or greater require a couple of weeks to get, and 2-by-6 planks are available if you want to put an overhead cap across your espalier or use them for trellises.
Because of juniper's density, you'll need to pre-drill holes for screws. Driving screws directly into juniper could overheat your drill motor.
ALTERNATIVES TO JUNIPER
* Cedar is rot-resistant but expensive. I prefer tight knot when using cedar, as it is less expensive than clear grain cedar and more stable than standard grade cedar. Sustainability is also an issue; be sure you're using Forest Stewardship Council-certified wood. Cedar is easy to drill for dowels, screws and wire.
* Redwood is similar to cedar, but it's difficult to find sustainably harvested redwood.
* Fir and pine are cheaper but rot.
* Steel pipe is durable but looks awful and is difficult to use.
* Plastic/wood fiber posts come in several colors. They are OK for edging raised beds but may bend if required to carry a load.
* Posts treated with copper naphthenate or other materials resist rot, but I prefer not to use them in my organic kitchen garden.
Posts such as 4-by-4s and 6-by-6s are less likely to twist, cup or bend than 2-by-4 lumber.
Posts of many types of wood can be found used at recycled building supply stores or at garage sales.
Use stainless steel screws to fasten juniper together. If you hide the screws with wood screw caps or mahogany dowels, use Gorilla glue to attach them. It is waterproof. If gluing juniper or another oily wood like cedar or redwood, wipe areas to be glued with acetone to dry out the oils.
Seal juniper and other oily woods with Penofin for Hardwood, Exterior Formula, which was formulated for harder, denser, oily wood. An alternative for those concerned about volatile organic compounds is Timber Pro's low-VOC Deck & Fence Formula, available in clear or 25 transparent colors. Use two coats.