Adapted from
Western Regional Master Gardener Conference 2000
Steve Priebe, Horticulturist
City of Phoenix Street Transportation Department, Phoenix, Arizona

People want plants in their yard. How they get there requires interaction between a consumer and a supplier. If you happen to be the consumer, then these notes and this session will be of service

Seed Source – Much of the material purchasable in local nurseries comes from seed. There are many other options--cuttings grafting, tissue culture, etc., that will not be discussed. Recently, awareness of the locality of the collection site of the seed has gained importance. Field observations, called a provenance test, have been done to find out if it really makes a difference and the answer is 'Yes!' As an example, if the seeds of a ubiquitous species such as Scott's Pine are collected from a variety of locations and then tested in the other locales (say, different vegetation zones), the seeds always perform better in the zone in which they were collected. Further, seeds grown out of their original collection site do not perform as well throughout their life. Again as an example, plants that are grown from seed collected in California may not do as well in Arizona as the same species of plant grown from seed collected in Arizona. "Endemism" is the condition of being endemic. Endemic means that a plant is not only native to an area in general, but is native to very specific sites within the area. For example, saguaros are native to the Sonoran Desert, but there are areas within the Sonoran Desert where they do not occur or occur very sporadically, as in the densely silted out wash plain between Phoenix and Tucson. They are endemic to the gravelly slopes of the upper bajada.

Nursery Application of the Seed Plant
When seed is collected and grown with the ultimate goal of selling it as a plant for use in the landscape, it must be germinated in a seedbed or in a small pot. Once germinated and it begins to grow, consideration of its roots and shoots must be taken. This means that as the roots grow and fill the container, it must be bumped up (transplanted) into a larger-sized container. If this is not done in a timely fashion or if little is known about the growth rate of the species and it simply grows faster than one thought, then the potential for root binding exists. A plant can be root-bound at any stage. For example, if a plant is root-bound at the one - gallon size and then bumped to a five-gallon container and allowed to root in, one might never know it had been root-bound at the one-gallon size until it begins to fail in the landscape.

Hint: in addition to checking a plant for general health and appearance, include an inspection of
the root ball. One of your first clues might be the "shoot to root" ratio. Not all plants, such as 15-gallon and larger, will be easy to root inspect. It is a good idea to become familiar with the practices of a nursery so one has confidence in making larger purchases in which the roots may be difficult to inspect.

Spatial considerations have a tendency to get the best of us. In the nursery, it is common to see plants crowded together. This is fine for many plants, but be wary of trees that have had their lower limbs removed for the sake of space-savings. Prolonged crowding can make a plant one-sided. Be sure to pull the plant you want out from the crowd and look at it from all angles.

Selection of Nursery – Inspection of grown plants should include observations for disease and insect infestation. Pass on plants with poor leaf color, abnormal leaf development or poor development of leaves. Obviously, a bit of familiarity with a good-looking, mature plant of the same species is advisable.

Pruning at this stage of a tree's life should be for strength and structure. No topping--that one-sidedness should not have been the result of pruning (look for pruning wounds and, if the plant has been pruned, look for "wound wood", a sign that the tree has been pruned properly). Ideally, a young tree should have branches on two-thirds of its main stem. The branches should be evenly spaced. In addition to being free from diseases and infestations, it should also be free of stubs, broken branches and flush cuts.

Post-Purchase Practices – In the nursery and, more specifically, in a container, the roots are above ground and subject to much more drying than roots that are planted and occur subsurface. Consequently, the nursery is likely watering the plant, regardless of species, on a daily or near-daily basis. Find out! When you plant it in the ground, it will dry much less rapidly, such that watering every day will be too much. However, take care not to underwater and stress a young plant. Watch for signs of drought and check the soil periodically until a regime is developed.

The watering regime used in most local nurseries has a tendency to flush out (leach) all the nutrients. To compensate, fertilizers are used in excess of what you are likely to need. Keep in mind that part about nativeness and endemism. The closer a plant is planted to the soil type it's adapted to, the less fertilizer it will require. Plants from soils unlike yours are more likely to develop nutrient deficiencies. In Arizona, as an example, citrus, pecans, roses, hibiscus, etc. should be fertilized regularly. Native trees such as palo verde, ironwood, mesquite, etc. rarely require supplemental fertilizer.

Pruning the first few years should be limited to dead, dying or diseased branches, crisscrossing and crowded branches and water sprouts. Young trees are like kids: full of energy. Pruning may be required more frequently than once per year, especially if the tree was planted in the wrong place.

Also like children, don't try to train them in one lesson (pruning event). Observe good horticultural guidelines for pruning. Never remove more than 30% of the tree at a given pruning. Let it bounce back before removing more. Leave the lower limbs; they are necessary for building a strong trunk both from food production and from wind dispersal. Prune for strength and good structure first and for art second. As the tree matures, pruning may be curtailed to once a year and then even to once every several years.

Good luck and, as Alex Shigo would say, "Touch trees!"

Posted: 22-Nov-2003