Tucson Botanical Gardens » Tree Connections

Tree Connections

Arizona State Forestry Division

TreeConnections, is a new, multi-faceted community education initiative focused on appropriate tree selection and care for urban desert dwellers. In partnership with the Tucson’s Midtown Neighborhood Association, project staff and volunteers took an inventory of 75 trees, developed and evaluate new tree signage and associated educational materials and volunteer-led tours and programs focused on urban desert trees. This program is designed to educate the Tucson community about horticulture and to promote education about trees and their importance to the health of the urban environment.

Pistacia chinensis

CHOOSING A TREE

SIZE – Be sure the size of the mature tree is appropriate for the location.

MESSINESS – Some trees drop large amounts of leaves and fruit. These trees are not ideal for locations near a pool, patio, or parking area.

EVERGREEN OR DECIDUOUS – Deciduous trees drop leaves during the winter. In the cold months they have bare branches which let sun through. Evergreen trees drop old leaves and needles throughout the year, but the trees are never bare. They provide year-round shade.

IRRIGATION – Even native desert trees will need watering when planted, and periodic watering for two years to establish. Some trees, such as citrus, have high water needs and require irrigation.

NATIVE vs. EXOTIC – Native desert trees are well adapted to our climate and will need little supplemental water. Exotic species may have higher water needs and some can become weedy.

PLANTING A TREE

LOCATION – Plant a tree where shade is desired, where messiness is not an issue, and where watering needs can be met.

SPACE – Be sure the location has enough space for the tree to grow and spread its branches.

TIMING – Fall is the idea season to plant a tree. Spring is also acceptable. Avoid planting in mid-summer.

DIGGING THE HOLE – The hole should not be deeper than the tree’s root ball, but it should be wider. Break up the edges of the soil ball. Back-fill the hole with soil from the site, use little or no additives.

ESTABLISHMENT – All trees will need a period of regular watering to establish. Reduce watering after a couple weeks. Supplemental watering may be needed for two years to complete establishment.

STAKING – Begin with a tree from the nursery which can stand on its own. If staking is necessary, do so properly, allowing the tree to flex. Wean the tree off the stake as soon as possible.

FERTILIZER – Most desert trees require little or no fertilizer. Citrus and non-native trees should be fertilized several times during the growing season. Do not fertilize newly-planted trees.

WATERING A TREE

KNOW YOUR TREE – Water needs will differ among tree species, and watering needs will differ in different sites, due to different exposures and soil types.

SEASONS – Adjust watering or irrigation with the seasons. Cease or reduce watering in winter and during rainy periods.

DESERT-ADAPTED TREES – water every 7-21 days in summer; every 30-60 days in winter.

HIGH WATER USE TREES – water every 7-10 days in summer; every 14-30 days in winter.

WATER AMOUNTS – Trees appreciate infrequent deep watering, rather than frequent light watering.

WATER THE ROOTS – and never the trunk. Most of the tree’s feeder roots are located at or beyond the outer edge of the tree canopy, and not near the base of the trunk.

ADJUST WITH GROWTH – Reduce or stop watering after trees are established. Move irrigation emitters out to the edge of the canopy and beyond, as the tree grows up.

CITRUS

CITRUS AND OTHER FRUIT TREES – have special requirements. These trees need more water and fertilization than desert trees, especially if a good fruit crop is to be produced.

LOCATION – plant a fruit tree where it can benefit from rain water runoff, such as near a gutter downspout. Locate fruit trees on an irrigation system, and in reach of a hose.

MESSINESS – locate fruit trees where falling fruit will not be a problem, but also plant them where the fruit can be reached and picked easily.

FERTILIZE – citrus three times a year, around Valentine’s Day, Memorial Day, and Labor Day.

SUN – citrus need a sunny location to gather the energy to fruit well. Some citrus varieties may need protection on cold winter days.

SICK TREES

WATCH YOUR TREE – You are the best detective for tree problems. Note any changes in how you have watered or treated your tree. Look for crusty salt buildup, wind damage, or fungus.

UNDERGROUND – Most tree problems in our area originate from problems underground. A dried leaf or withered branch will not tell the whole story of what is wrong.

WATERING – Underwatering is a common problem, especially in summer. But overwatering will also kill trees, especially if the tree is planted into a pit in compact soil that doesn’t drain.

BAD ROOTS – Some trees are strangled by wound-up roots, a problem that started in the nursery pot. Watch for, and do not buy or plant, a tree with girdling roots.

SOIL SALTS – Salts and minerals can build up in soil over the years, especially around trees that have not been watered deeply. Some trees are more susceptible. Flushing the soil with heavy watering can dispel the salts.

TEXAS ROOT ROT – is a pathogenic fungus which attacks many tree species. Look for dead leaves which remain on the tree during the heat of summer. Remove infected trees.

REPLACEMENT – replace a dead tree with a different species. Whatever killed the first tree could infect the next if replaced with the same kind. If root rot is suspected, consult a list of species which are resistant.