Best Time to Plant Mountain Trees

16 March 2018

Tree Type Helps Determine Best Time for Planting. How to plant shade trees and evergreens. Watters' Spring Open House, March 16 -18, with tree planting demonstrations all weekend.

When is the best time to plant trees in the mountains? This question, pertaining to areas that experience cold winters, has both a long and a short answer.

When to Plant Trees: The Short Answer

In general, the best time for planting trees is late winter to early spring (February thru May).

This period typically is followed by a period of moderate weather, a good time for a new transplant to become established. If your schedule does not allow for a spring planting, then aim for autumn. Trees can be planted in summer in the mountains of Arizona, but closer attention to irrigation is essential.

When to Plant Trees: The Long Answer

For the long answer of when to plant trees, remember what has been said above, then add some elaboration. At this point, let's introduce some garden vocabulary:

Dormancy is defined as the time from when a tree has dropped its leaves in fall and before new leaves appear in spring. Planting trees when they are dormant (when they are not operating at their peak growth rate) is best. When trees are dormant they are less disrupted by harsh handling and transplant shock. Yes, our mountain climate is mild enough that trees can be planted in mid-summer, but with greater care.

Deciduous trees are those that lose their leaves in autumn. The dropping leaves signal that those trees are entering dormancy; their unfurling of buds in spring signals they are leaving dormancy.

Evergreens do not undergo the kind of dormancy that deciduous plants do. As they do not send out the clear seasonal signs of dormancy, when to plant them is not easy to determine. Fortunately, evergreens tend to be truly tough trees, allowing more leeway in their planting times. Planting is ideal from fall through late spring. With many juniper, cypress, and cedar varieties planting continues well into the heat of summer. Again, summer heat mandates that newly planted evergreens be watered twice per week.

Now that you know when to plant trees, what about the how?

Trees, especially native pines, have trouble with our crummy mountain soil. They don’t like to sit in wet soggy soils. In a wet environment trees’ internal metabolisms are slowed to an almost stasis-like state. New root hairs will form along with next spring’s buds as long as the soil drains properly. That’s why digging the right size planting hole and adding the correct soil amendments are critical towards a successful planting.

Here are the six steps to planting a tree successfully, no matter the season.

Step 1 – The bowl-shaped hole should be the same depth as the root ball, and three times as wide. Plants do not need a deep hole; they thrive when able to stretch out just under the surface of the soil in search of food and water. This is why a bowl-shaped hole promotes the best root development. Rid the hole of rocks and debris larger than a golf ball.

Step 2 – Improve the planting soil by amending with 'Watters Premium Mulch'. Good mulch will keep clay soils loose and aerated, and in loose granite will retain water up around the root ball. The amount of mulch per plant should be equal to the size of the root ball. That is the quantity of mulch you will need to blend into the native soil used to fill in around each plant.

Step 3 – Trees are so sensitive to soggy soil it's recommended they be planted on a slight mound. Do NOT bury the plant; keep the trunk out of the soil. The top of the root ball visible in the grower’s pot should still be able to see sunlight once planted.

Step 4 – Trees need the right plant food for a healthy start. Use my specially blended “All-Purpose Plant Food” 7-4-4, specifically designed for Arizona's mountain plants. Just sprinkle the granules on top of the root ball and water in well. The slow-release nutrients promote a plant's deep green color while encouraging thicker root formation each time it is watered.

Step 5 – Promote deep roots for a new planting by using Watters ‘Root & Grow’. Add this liquid rooting hormone to the water you use to saturate the newly planted root ball. It forces many new root hairs to grow into the surrounding soil. More roots mean a more vigorous plant. Use this root tonic once per month until new leaves or evergreen candles emerge in spring.

Step 6 – Top dress the planting area with a 3-inch layer of shredded cedar bark. This extra layer of nature’s insulation retains moisture, keeps out weeds, and protects from extreme temperature swings. It is like pulling a thick wool blanket over the roots when they are cold and shivering.

Water – Give newly planted trees a thorough soak twice per week throughout the growing season. Keep established trees moist, but allow them to dry between waterings.

For exact planting details that include drawings and measurements, ask for my “Guide to Mile High Planting”the next time you visit the garden center. You might also like the useful companion guide “Mile High Watering”.

Watters 56th Spring Open House - consider this a personal invitation:) We've stocked up on trees for this year's open house and brought Watters' growers off the farm to share their knowledge with local gardeners. It's the ideal week to plant a new fruit, shade or evergreen tree.

Until next week, I'll be here at Watters Garden Center helping local gardeners plant the perfect trees.

Ken Lain can be found throughout the week at Watters Garden Center, 1815 W. Iron Springs Rd in Prescott, or contacted through his web site at or

Gardening Classes sure to make you a better gardener

March 17 – Watters' 56th Spring Open House – Meet the Watters growers, talk directly to the professionals, and experience many of this spring's new plant introductions available only here at Watters Garden Center.

March 24 – Trees of Spring

Spectacular blooming trees are the talk of the town every spring in northern Arizona! You will be an expert on the best ornamental bloomers for our mountain climate. Learn which trees are fast-growing, give the best shade, and are the most low maintenance varieties. Watters’ garden experts will give you the scoop on all their local favorites, and how you can pick the best trees to fit your space and your style in your home landscape.

March 31 – Advanced Container Design

The right container with the right plants can bring a space in the landscape from so-so to stunning. Lisa Lain, owner of Watters Garden Center, has been creating container designs for decades. Her 3-step program puts the floral style back into your garden. The class is free to onlookers, but the first 12 students to sign up can create their own design with Lisa’s professional guidance for a $35 fee (pots provided). Come ready to get your hands dirty and your containers beautified!

April 7 - Drip Irrigation Design and Installation

April is time to get that irrigation system back up and running. Learn the benefits of drip irrigation, new technologies, and how to set a system up or add a plant to it.  With the right irrigation, you can save water and have healthier plants all at the same time.  Don’t know how to install and run an irrigation clock? We’ll teach you! Watters’ irrigation parts bins will be full in preparation for this class.  Come early and bring a lawn chair; over 100 students attended this class last time it was offered.

April 14 - Planting Advice that Works

Ready to start your garden, but just want a little extra help? This class will take an in-depth look at how to be successful when planting your personal paradise. We’ll discuss techniques for brighter, more beautiful gardens, and how to keep them healthy. Learn how to troubleshoot and combat problems like poor soil conditions, pests, and diseases that can frustrate any gardener from a master to a novice. Bring your notepad!

April 21 - Go Native and Low, Low Maintenance

Go native! Native plants add unique appeal to our arid climate landscapes while giving gardeners a break with their low maintenance habits. Learn which Arizona and southwestern native plants are best for your garden, along with a host of other LOW, LOW water use plants that once established require little to no water and even less care.  No other nursery has so many native and low care plants in the region with a horticulturist to help you plant it right. This class coincides with our annual native plant sale.

April 28 - Growing Your Own Groceries – Ladybug Release Weekend

This fun-filled class has everything edible for the garden this spring! We’ll cover the best heirloom varieties to local favorites, and highlight soil preparation, best foods, and care.  It’s the start of planting season, and this class arms participants with advice to prepare the garden for a great harvest of fresh veggies and herbs. The nursery is loaded with hundreds of non-GMO vegetable starts and organic herbs this weekend.  Let’s get ready to plant!

After the class, our Annual Ladybug Release is a fun event for young and old alike.

Open this link to see all of Watters classes this spring.


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Ken Lain, the Mountain Gardener

Ken Lain is attracted to sunshine, beauty, happiness, success and health through gardening, and wishes to point the way to others. Throughout the week Ken can be found at Watters Garden Center located at 1815 W. Iron Springs Rd, Prescott, or contacted through his web site at