For convenience
many builders and landscape contractors will "warehouse"
landscape trees and shrubs at the construction site for days or
even weeks before they are to be installed. In many respects,
the average landscape construction site can look deceptively
like a nursery, making onsite storage an all too common
practice. But landscape plants, unlike lumber or plastic pipe,
require special care and attention when stored if damage or
serious injuries are to be avoided.
The greatest risk
to tree health is poor irrigation practices, particularly in the
summer heat. In the nursery trees are watered slowly using fan
spray emitters that distribute water evenly over the soil
surface. Box trees are often watered twice a day when day
temperatures exceed 80° F and night temperatures are 60 to 65°.
Watering trees quickly with a hose does not saturate the root
ball the way fan sprays do. It is often difficult and expensive
to have adequate labor available to properly water trees once a
day much less twice. Trees will be damaged or die if left
without irrigation for more than one day during hot weather. As
the rootball dries it contracts and can separate slightly from
the side of the box. Water applied at high pressure to the
surface will leak down these separation and out the bottom of
the box giving the irrigator the false impression that the tree
is well watered. Re-hydrating the rootball takes long, slow
irrigation.
Winds damage
trees in two ways. Hot, dry summer winds rapidly dry leaves and
increase the need for timely irrigation. Winds can also push
boxed trees over breaking branches and trunks. Falling trees can
also damage adjacent stored trees.
Equipment is
another source of injury. Trees are particularly at risk during
unloading, placement and installation. For the safety of workers
and the health of the tree, handling and planting boxed trees,
especially large boxes, should be done only by experienced
equipment operators. When using ground operated equipment or
cranes, make sure that boxes are well secured and that chains,
cables or straps are not attached to trunks or branches. DO NOT
remove the bottom of the box.. The bottom helps keep the
rootball protected and in one piece during transplanting. DO NOT
remove the sides of the box until it is in the planting hole and
backfilled two thirds up the sides. Rootballs should be moist,
but not soaking wet, while planting.
Once installed,
equipment operators (those of the landscape contractor as well
as those of other sub-contractors), should be careful when
operating equipment around trees since both impact and excess
soil compression can damage trunks, branches and rootballs. Many
machines, like backhoes and front loaders, release intense heat
and pollutants directly onto the canopy of trees from exhaust
pipes that are mounted above the engine.
If you must store
trees onsite, consider the following: arrange trees in groupings
or rows that will help them resist being blown over and damaged
by winds; allow sufficient space between trees so their branches
do not become tangled while in storage and subsequently broken
when trees are selected for planting; set up a temporary drip
system with a manual, battery or electric value; monitor the
trees regularly to insure that the irrigation system is
operating properly and trees are receiving slow, frequent
irrigation; schedule deliveries so that trees are stored the
shortest time possible and avoid storing trees over the weekend
(2 day and the occasional 3 day weekend).
If you have any
questions about installing trees, the University of Arizona in
cooperation with the Arizona Landscape Contractors Association (ALCA)
has produced an excellent video tape on planting landscape
trees. This tape, "Planting and Staking Landscape
Trees," is available through the Agriculture
Communications Department of the University of Arizona.