Leyland Cypress trees catch a lot of wind! A deciduous tree like Maples or Oaks have leaves that turn on edge to let the wind pass through, but Leyland Cypress and Thuja Green Giant trees catch the wind. It is important to use the appropriate stakes and tie material for each tree size and also important when they should be removed. For Ball and Burlap trees especially, the root system to trunk connection will have loosened due to loading on the truck, transport to your location, and unloading. Securely staking them will allow that connection to re-tighten and also they will be straight when established. Explained below is exactly which stakes to use, how to tie them and where to obtain the material I recommend. Proper staking is one of the most important steps for success. Save your money on mulch and spend it on securing your privacy screen trees.
Ten feet and taller trees should be staked with six feet metal fence posts so that each tree is secured in three or four directions. Allowing them to blow back and forth, it will break the trunk to root ball connection, and you will loose a percentage of the row. Ball and Burlap trees from ten feet tall up to twenty five tall should be staked with tree tie webbing from am Leonard item LT500G, I prefer the green color. It is soft around the trunk yet still has 900 pound test strength. Landscapers have used have used electric fence wire or rebar wire pushed through twelve inch sections of garden hose for years which will work for smaller Ball and Burlap(B&B) trees up to twelve feet tall, but is not strong enough for taller trees and also takes lots of time and dull knifes cutting all that garden hose. I always return one year later and collect back my tree stakes and it is very important to cut the tree tie webbing from around the trunk. It is best to use an arborist knot that will hold on but still allow some stretching when you secure around the trunk but I also wouldn't be sure your helpers used it consistently on every tree. If you are faithful and remove the tree tie webbing after one year, the tree will not be hurt even if other knots were used.
Fourteen feet and taller trees are best staked by securing the tie around the trunk midway up from the ground so an eighteen feet tall tree would be tied at eight feet from the ground. For trees this top heavy, you should not tie to a metal fence post directly in front of the tree because as the wind rocks the tree it will pull the stake up. If you use six feet metal fence posts on trees this large, secure the tie from each tree to the bottom of the tree stake right at ground level in front of the next tree along the row. If you had trees spaced at eight foot on center, and reached up and tied the webbing eight feet high on the trunk, your lines would be at forty five degree angles. Long Island landscapers use three to four inch diameter pine poles available from Lynch's garden center in Southampton. Drive in the ground at 45 degree angles away from the trunk. These are strong stakes but still the lines should be tied up high on the trunks and the lines should be at forty five degree angles for strength to the stakes. Smaller Ball and Burlap trees can be staked with three ply poly twine, it usually comes in white and has an advantage in that it rots away after one year. This is perfect for landscape jobs a good distance away that you might not want to return just to release the tie material.
For seven feet tall B&B trees in twenty-two inch root-ball you can stake with two inch by two inch hardwood stakes six feet tall and use the poly twine or tree tie webbing.
When planting ten gallon size container grown trees five tall I use one inch diameter eight foot tall bamboo stakes they can be purchased for around one dollar each. For this application, use a post driver tool and drive the stake down through the root-ball into the ground below and use the poly twine. You won't have to return to the job and collect the bamboo stakes, the portion underground will be rotten by that time and the ply twine will have rotted away as well. After six months walk the row of trees and re-tie anywhere the twine has rotted away, so for spring planted trees they would be re-tied in fall.
David Watterson and Family have been growing trees in NC since 1995 and now grow trees in VA and have an affiliate nursery in GA. Wholesale and have a $2,500 minimum order. Trees from 7' to 25'. Http://www.leylandcypress.org