Pruning should be done to maintain plant health (remove dead, damaged or diseased portions, cross branching, etc.), to highlight the “natural” shape of the plant, to train a young plant, and to eliminate hazards. Excessive or heavy pruning causes significant stress to trees and shrubs. The best practices are to prune the least amount necessary and prune for legitimate reasons. How much to prune depends on the size, species, age, as well as your intentions. Two good principles to remember–a tree or shrub can recover from several small pruning wounds faster than from a single large wound and never remove more than 25% of the canopy in a year. For more information register for a Garden class offered on pruning that will teach you the proper pruning techniques for trees and shrubs or visit http://www.treesaregood.org
for information on proper pruning of young and mature trees.
If necessary, native and desert-adapted spring-flowering shrubs can be pruned after flowering has diminished. However, prune before the upcoming hot, summer months. For more information on pruning shrubs go to the University of Arizona Cooperative Extension at:http://cals.arizona.edu/pubs/garden/az1499.pdf
Lightly prune your Mesquites (Prosopis spp.) and Palo Verdes (Parkinsonia spp.) to remove dead and crossing branches.
Pruning newly planted trees and shrubs is not recommended and in fact, can be detrimental. However, at planting time prune broken or torn and diseased branches. Save other pruning activities for the second or third year. For more information on developing a healthy tree visit http://www.treesaregood.org
Prune Prickly-pears (Opuntia spp.) or Chollas (Cylindropuntia) after flowering. If pruning your prickly-pears or chollas to maintain size, for propagation or to remove a damaged or diseased stem, prune at the joint or segment. Use a sharp, clean pruning tool and spray tool periodically with a 70% alcohol solution to prevent infection. If the pruned stem is to be used for propagation, allow the cutting to dry out for a week before planting.
Continue to remove spent stalks of aloes, agaves, and other succulents.
Spring-blooming perennials such as Penstemons (Penstemon spp.), Brittlebush (Encelia farinosa), Globemallow (Sphaeralcea ambigua), Fleabane (Erigeron divergens), and Golden Columbine (Aquilegia chrysantha) should be producing seed. Allow them to produce seed before pruning spent flowering stems. The seed is a valuable food source for many animals.
Deadhead herbaceous perennials to encourage continued flowering including Desert Marigold (Baileya multiradiata), Chocolate Flower (Berlandiera lyrata), Red Sage (Salvia coccinea), Mealy-cup Sage (Salvia farinacea), Gaura (Gaura lindheimeri), Tickseeds (Coreopsis spp.), Angelita-daisy (Tetraneuris acaulis), and Gaillardia (Gaillardia pulchella).