Spray existing weeds or grass with Round-Up® and rotor-till the area where the trees will be planted. If the soil has a high sand or clay content it would be beneficial to add 3-4" of organic matter; compost is ideal, but peat moss or rotted wood chips would be acceptable as well. Till this organic matter into the soil to help condition the soil for better water holding capacity and better soil structure.
Till in approximately one pound per 50 square feet of a general 10-10-10 fertilizer, which will provide necessary fertility as the plants develop. Fertilizing over the top with a liquid fertilizer, such as MiracleGro®, once every 2-4 weeks once the plants are established is also helpful. Fertilize once a year after the trees or shrubs have been established for a year.
Dig a hole large enough to accommodate any "root fan" that exists on a bare root tree or shrub without having to bend and tuck to make the roots fit. Bigger is better when digging holes for plating. Insert the plant so that the transition zone, where the root meets the trunk is buried just an inch below the surface of the soil. Do not plant too deep, as this is a common mistake, and can lead to problems including decline or death of the tree. This is very common with certain tree species, and we see this occur much too often, and it is easy to avoid. Trees planted too deep often end up with tiny root hairs that grow around the trunk, and lead to "strangling roots" later in the tree's life. Those tiny root hairs grow into large roots that circle the trunk near the base, and end up embedding into the bark and making the trunk weak and often indented. The tree looks normal above the ground, then snaps off just below the surface, during a light wind, when the canopy has just reached a beautiful height and width. This is always a heartbreaking occurrence and happens much too often, especially with maple varieties, and can be completely avoided by simply planting at the proper depth to start with.
Water slowly and deeply on planting day, as the water will seal the dirt around the roots and keep them from drying out. Keeping the soil moist for the first several weeks is important. If Mother Nature doesn't provide moisture then it is important that water is provided by your garden hose. Make a shallow dish in the soil around the trees roots, to hold water and allow it to soak into the soil slowly. Another great way to deeply water trees is to punch a nail hole in the side near the bottom of a five gallon pail. Fill the pail up with the hose, and the small nail hole will meter out the water slowly so that the water has time to be absorb and doesn't run away across the surface. For watering a row of trees or shrubs, a soaker hose, or drip line irrigation, works very well for slow and even application. To check moisture levels in the soil simply stick your finger in the ground; if it feels moist within the top two or three inches then there is likely enough moisture, if not then get out your garden hose.
Many of our customers intend to plant a long row of these Willow trees or other trees in order to create a wind break or visual barrier. If you only have ten or twenty trees to water it doesn't take long, but if you have 500 or 1,000 trees planted in a long row across a field in can take hours to water if you plan to use a hose and go from tree to tree. We suggest the following which has proven very successful over the years. Use a single row digger to make a furrow or shallow trench that is about 6-8" deep and wide. Plant the trees or shrubs in the bottom of the trench, but keep the trench open so water can flow down the trench past the tree planted in the bottom of the trench. Now put your hose at the top of the slope and let the water trickle all the way down the hill and each tree will get saturated roots and be well watered with very little effort.
Pull, hoe, rake, cut or somehow remove weeds and grass that sprouts near your newly planted trees and shrubs. Weeds compete for moisture and fertility and will stunt the growth of the trees or shrubs. Keep all weeds and grass at least three feet away from the base of all new plantings. You can use Round-Up again if necessary, but instead of spraying it on the weeds, use a sponge mop and wipe the weeds with the Round-Up, which will protect accidental drift of the spray onto leaves of the plants you want to keep. There are other pre-emergent herbicides that can be put down after planting to control weeds. Snapshot is one that seems to work well, on a smaller scale using Preen also seems to work pretty well.
Mulching - A terrific way to hold in moisture and prevent weed growth around the base of young trees and shrubs is to add a thick layer of mulch around the base of each plant. The mulch must be a minimum of 4-5" thick once compacted and settled to prevent sunlight from reaching the soil underneath and sprouting weed seeds. DO NOT use landscape fabric or plastic underneath the mulch. Many different types of mulch are available such as hardwood shredded bark, cedar mulch, or cypress mulch. Often local tree removal companies can provide bulk wood chips that will do the job, but may not look as attractive. Using a base of 4 inches of rough, cheap mulch, and putting 1 or 2 inches of more attractive mulch over the top can be an economical way to get the job done.