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Tree Calendar

Integrity Tree Service, Inc. is committed to providing our customers comprehensive and up-to-date tree care information.

Tree Care Calendar –

This Calendar is designed to help you care for your trees through the various seasons in the Arizona low desert. Our temperature extremes, low precipitation and unique soil conditions present challenges to tree owners. Here’s a heads-up on things to consider each month to keep your trees healthy, safe and beautiful.

| Jan | Feb | Mar | Apr | May | Jun | Jul/Aug | Sep | Oct | Nov | Dec |


  • January, like December, is a great time to trim deciduous trees like elm, ash, desert willow, chaste tree, peach, plum and other stone fruits.

  • Leave citrus, ficus and other frost-sensitive trees alone right now. They still need their winter coats for a couple more months.

  • Trimming of vigorous evergreens is OK if it’s not too cold and the pruning is not too heavy. As in December, if necessary you can give trees such as sumacs, eucalyptus and mesquites a light semi-annual pruning to keep them safe until heavier pruning in the summer.

  • If you plan to spray your olive trees to reduce fruiting, pruning them now before they are sprayed will help give your spray applicator better coverage.

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  • You should schedule citrus and frost-sensitive plant pruning after February 15, the average last day of frost in Phoenix. Pruning can be done through the end of March. This timing starts after the danger of frost damage but before citrus blossoms set for next season’s harvest. February/March pruning also allows the new growth following pruning to “harden off” before high temperatures arrive. You can check out your area’s average last day of frost here:

  • Heavy cutting back of certain shrubs and trees can be done during this time frame too. If pruned now, new growth will have time to harden off before hot weather arrives. (For more information on shrub restoration and rejuvenation, see the article Salvaging Sheared Shrubs.)

  • You can still spray olives this month.

  • Although light pruning can be done year-round on deciduous trees, early February is the last month for heavier crown reduction and thinning.

  • Now is the time to put down the first of four applications of citrus fertilizer (Feb/May/Aug/Oct).

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  • Now is prime time for pruning most evergreen trees and shrubs.

  • This is the last chance to prune citrus and ficus and other sun-sensitive trees. Be careful. If you wait too long, new foliage will not have time to fill in before sun damage occurs. As a rule, any area of bark exposed to direct sun for 3 or 4 hours needs to be protected with shade cloth or tree wrap to prevent sunscald. (For more information on sun protection, see the article First Aid for Sunburned Plants.)

  • There are two general rules for pruning flowering trees and shrubs: For plants that produce blooms on old wood or last season’s growth, prune as soon as possible after the bloom ends. For flowering plants that produce blooms on new wood or this season’s growth, prune in late winter or early spring.

  • March is a good month for fertilizing all trees.

  • It’s also a good time to apply a 2-3 inch layer of mulch around the base of trees and shrubs. This relatively inexpensive soil amendment does more to improve growing conditions around desert plants than any other treatment including fertilization. It reduces soil temperatures, runoff and evaporation, encourages nitrogen cycling and improves soil microbiology.

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  • Now’s the time to check your irrigation system for proper function and reset your timer for hotter temperatures.

  • Increase duration, not frequency, of watering cycles as temperatures increase. It’s better to water deeply and less often, especially if your trees are in turf settings. Be careful not to over-water though. It’s a two-edged sword. It has been said that more trees die in Arizona of over-watering than under-watering. Ideally the root zone should dry out entirely between waterings. Avoid putting water on top of water. (For more information on irrigation, see the article How Best to Water Your Trees.)

  • March and April are great months to plant citrus and most other trees as soil temperatures have warmed up and root activity increases.

  • There may still be time to spray your olives, but you need to schedule soon.

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  • May is a good time to prune trees to prevent storm breakage during summer monsoons in July and August. Alleviate end weight on heavy branches. Mesquite and eucalyptus trees are especially prone to wind damage.

  • If your trees have been lion-tailed in the past, consider pruning them properly to alleviate end weight. Lion’s tailing is an unacceptable pruning practice. It removes an excessive number of interior branches along the trunk and main branches. Not only are these smaller branches critical to protecting the tree from sunburn; they also help their host branches develop taper that is needed to support increasing end weight as the tree matures. (For more information on lion’s tailing, see the article The Art and Science of Good Pruning.)

  • Trim date palms in May. If you wait another month, the dates will be larger and heavier and the clean-up and hauling is more difficult and expensive.

  • May is the month for the second application of citrus fertilizer. (Feb/May/Aug/Oct)

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  • Monsoon winds are right around the corner. To reduce the risk of tree or branch failure, schedule pruning of large trees including mesquites, sumacs, eucalyptus and other vigorous tree varieties.

  • Install or adjust staking systems on younger trees. Staking ties should be strong enough to keep trees upright in strong winds but loose enough to allow the trunk to move slightly.

  • Trim Mexican fan palms after June 15th to be sure to get all the seed pods in one trimming. You can also trim Queen palms anytime after June 1st but expect some seed pods to continue to emerge through the fall.

  • The heat of summer is the best time to plant and transplant palm trees.

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  • Life in the desert is on simmer. Monsoon storms are here now or due very soon. Batten down the hatches, adjust tree stakes and enjoy the rain! Watch a baseball game or escape to the mountains and listen to the wind whistle through the pine trees. Go Diamondbacks!

  • Trim California fan palms after July 15th to insure getting all the seed pods in one trimming. If you don’t want to put up with all the yellow pollen until July, you can prune the trees earlier, but you’ll need to trim the trees again later in the year to get the rest of the seed pods.

  • Prune mesquites and eucalyptus trees now if you haven’t pruned them yet. There are two main reasons for summer pruning: First, these trees effectively compartmentalize pruning wounds, especially during this time of active growth so it’s safe to prune in the extreme heat. Second, because they are near the end of their spring and summer growth, they “hold their prune” for more of the calendar year following the pruning. Keep in mind that the longer you wait to prune your mesquites, the higher the risk of wind damage during the monsoon.

  • August is the month for the third application of citrus fertilizer. (Feb/May/Aug/Oct)

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  • As air and soil temperatures begin to drop in September, you can resume trimming most evergreens, both hardwoods and conifers.

  • If daytime temperatures have dropped into the 90’s, you can plant and transplant evergreen trees and shrubs. They’ll still have time to get established before cold weather arrives.

  • If your mesquites and eucalyptus trees survived the monsoons, it’s a great time to prune them. Because they had their spring and summer growth, they’ll now hold their prune for more of the calendar year.

  • If you plan to over-seed your lawn in October, prune your trees now to avoid dropping and dragging brush over the new seedlings.

  • September and October are also good months to fertilize your trees. Research has shown that stored nutrients from fall fertilization produce vigorous growth in the spring. Plants seem to hit the road running, so to speak.

  • If a soil sample indicates you don’t need fertilizer but your plants are still showing signs of stress, it may be time to apply a 2-3 inch layer of finished compost around the base of your trees and shrubs. This relatively inexpensive soil amendment does more to improve growing conditions beneath desert plants than a lot of other treatments including fertilizer. Compost can reduce soil temperatures and water loss through evaporation. It encourages nitrogen cycling and improves soil microbiology. It reduces runoff and erosion. It controls dust and weeds. It even cures the common cold. Ok, maybe not that last one but compost is still one of the best ways to assure plant health, the natural way.

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  • If temperatures remain mild, you can safely prune most trees. Every year is a little different so watch the weather reports for changes from seasonal patterns. If there are warnings of an early cold snap, be careful not to prune frost-sensitive trees too heavily. You’re taking away their winter coat! New growth that emerges after pruning is also more susceptible to frost-damage than older growth.

  • October is a great month for planting and transplanting evergreens. There are also a few beautiful deciduous trees in the Phoenix area that give a brilliant display of fall color. One that does exceptionally well here is the Chinese Pistache (Pistacia chenensis.) To see a wonderful specimen, visit the Arizona State University campus just outside the main doors of the Agriculture building.

  • This is also the month for the fourth and final citrus fertilizer application. (Feb/May/Aug/Oct)

  • Is the frost on the desert pumpkin? Probably not quite yet…

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  • As temperatures begin to drop, lighten up the pruning on most evergreen trees except for deadwood removal and structural improvements.

  • For more vigorous trees like mesquites, olives, sumacs and eucalyptus, a little more pruning can be done. In fact we recommend a semi-annual light pruning of trees pruned in May or June. Because most mesquites can’t safely go a full year on their summer trimming, it makes sense to prune them again now. This semi-annual interval also has the benefit of readying the trees for the holiday season.

  • It’s a great time to begin or add to a compost pile with all your raked leaves and other fall yard waste. By early spring you’ll have the best top dressing and potting soil around.

  • If you plan to put up lights for the holidays, it’s helpful to prune your trees ahead of time. It makes removal of the lights easier too. Also, don’t nail or staple wires to branches. Use gardening tape or twine instead. And to prevent girdling of branches, remove lights from trees after use.

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  • Citrus fruits begin to ripen now. Change in color is due to cooler temperatures but may not always indicate sweetness.

  • Deciduous trees should be pruned now through February. These include mulberries, pecans, elms, ash, desert willows, chaste trees, stone fruits and others.

  • Shrubs like Mexican bird of paradise, lantana, yellow bells, orange jubilee, bougainvillea, oleander and cassia can be cut way back. (For more information on shrub restoration and rejuvenation, see the article Salvaging Sheared Shrubs.)

  • As in November, December is a great time to remove deadwood from any tree. It’s also a good time to plant or transplant deciduous trees. Deciduous trees planted on the south side of a house provide summer shade but allow sunlight through during winter when the leaves are off. Happy Holidays!

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