The Natural Gardner had wire cages wrapped in a frost protection material for an early start on plants that cannot take cold weather. The material looked like this found at Gardener's Supply.
Any wire fence will do, but this is probably wire used when pouring concrete.
This is one type of clip which can probably be found wherever fencing materials are sold. Some cages had only one layer, others two and three layers.
In this instance bamboo polls were used with heavy clips.
Just thought I'd pass along some ideas for you in the north country. :D In fact, I'm will have this fabric on hand next year when I plant the bare-root strawberries. I only have to lose 40 plants to a hard freeze one time to learn what to do the next year! Our planting guide said to do the bare-root strawberries in late January or early February. The two-week hard freeze in February was unusual for us in Central Texas and I just didn't think to cover the strawberries. Duh.
Until next time, God bless.