Answer: You can tie them to try to provide a broader base of support to hold the weight of the snow and prevent breakage. Here are instructions with diagrams on how to do that. You may need to cut and paste the complete url into your browser to make it work correctly.
Burlap is often used as a wind screen, so perhaps that is why burlap was also recommended.
You can also go out during the snowstorm and brush the snow off perodically (use your arm or a broom, when they are larger) to prevent the snow building up to a heavy weight.
I hope this helps.
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