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April/May 2024 Garden Checklist and Solutions

By Noelle Johnson | Illustration by Gary Hovland

We are entering the most colorful time of year in the desert garden when bloom seasons overlap as winter and spring flowering plants add vibrant interest to the landscape. This is the time of year when Arizonans are the envy of residents of cold winter climates who flee to the desert to enjoy our warm weather and beautiful outdoors.

Spring is the busiest time of year in the garden, especially when it comes to pruning and fertilizing. Often, plants are automatically pruned at this time of year, whether they need it or not. The truth is, that we tend to over-maintain many of our shrubs, often to their detriment. Before you trim, check out my guidelines below that will lead to healthier and more attractive shrubs with less work.

In our next issue, I will share my best tips for creating a heat-proof garden that thrives through the summer. I welcome your questions, which may be featured on these Garden Solutions pages. Please direct your queries to info@azplantlady.com.

Before we know it, the summer heat will be here, so I invite you to take time to enjoy our wonderful weather within your own outdoor space and experience the unique beauty that exists in the desert garden.

Noelle, aka “AZ Plant Lady,” azplantlady.com

ADD SUMMER-BLOOMING ANNUALS BEFORE IT GETS HOT
One of the best ways to bring bright splashes of color to outdoor spaces is by adding flowering annuals, such as angelonia (Angelonia angustifolia) and gomphrena (Gomphrena globosa) to containers and other high-profile areas in the garden. However, if you plant them too late in spring, they can have difficulty growing roots and becoming established due to the heat. When first placed in the soil, the priority is to grow roots to enable them to take up water, which is vital to summer survival.  This means that you will likely have to pull out your cool-season flowering annuals while they are still blooming, which can be hard. However, it is necessary to ensure healthy plants through the summer.

To accommodate our patio’s new design, our landscape architect has suggested relocating our beloved olive tree to a different spot in our yard. We are worried about replanting and whether it will be successful. 

You are right to be concerned. The older and larger a tree is, the more stress it will undergo when transplanted to another area—and there is the chance that it may not be successful. Whenever a plant is relocated, it loses a percentage of its roots, and its ability to take up water is reduced. According to ISA-certified arborist Jason Klug, the key to maximizing the success of moving a tree is to keep its roots intact. The use of a truck with a large hydraulic spade that will scoop up the tree and its roots and move it to a prepared hole is your best method toward success. Due to the variables involved, relocating a tree should be done in consultation with a certified arborist.

Illustration by Gary Hovland
Low to Middle Elevations

Now is the ideal time to cut back shrubs and groundcovers. For those that bloom winter into spring, prune them back by up to half size once the flowers have faded. For plants that bloom in spring and summer, pruning is done once the threat of freezing temperatures has passed, which is typically in March, and sometimes again in late summer if they are outgrowing their space. 

Get rid of stinknet, also known as globe chamomile (Oncosiphon pilulifer), a highly invasive, highly flammable weed that is rapidly overtaking natural desert areas and home landscapes. This flowering member of the daisy family has become more prevalent in recent years due to our generous winter rains, allowing it to outcompete native desert flora. This unwelcome guest begins to grow in winter and flowers in spring before dying in summer. The foliage is finely textured like a carrot leaf, and the plant produces globe-shaped, yellow flowers, which when crushed, release a foul odor. As they dry up in summer, each tiny bloom releases up to 100 seeds, so it’s important to remove them before they turn brown. 

Globe chamomile (Oncosiphon pilulifer)

Prune summer-flowering shrubs now, if needed to reduce their size or remove wayward growth. If you intend to do any severe pruning, now is the best time to do it. For shrubs that bloom once a year in winter/spring, such as feathery cassia (Senna artemisioides), ‘Little John’ bottlebrush (Callistemon ‘Little John’), or ‘Valentine bush (Eremophila maculata), wait to cut them back after their flowers have faded.

Directly sow warm-season vegetable seeds, such as bush beans, cantaloupe, cucumber and okra outside in the garden. Transplants can also be added instead of using seeds. There is no need to dig up the garden ahead of each growing season. Add 2 to 3 inches of compost, and lightly mix in bone and blood meal before planting.

Transition to summer flowering annuals in mid-spring to allow them time to grow roots before the heat and stress of summer arrives. Have fun trying some newer types, such as Angelonia, which has flowering spikes and comes in many different colors, including white, peach, red, purple and pink.

High Elevations

Prune trees in early spring if needed, removing any dead, diseased or crossing branches. A dead branch will make a cracking sound when pulled, while a live one will be flexible and have a thin, inner green layer under the outer bark. Shrubs that flower in summer and fall (but not in spring) should be cut back before April, including roses. 

Wait to clean up garden debris until temperatures are over 50 degrees. Pollinators, such as bees and butterflies, overwinter underneath fallen leaves in the garden. Removing dead flowers, leaves and stems too early means you’ll get fewer pollinators in the summer and fall.

Begin broccoli, cauliflower and tomato seeds indoors for them to be planted outdoors in the summer. Annual flowers, such as cosmos, marigolds and zinnias, can also be sowed inside. Use LED lights, which are more reliable than fluorescent lights, to maximize growth.

I love having aloes in my garden, but over time they multiply, outgrow their space and form dead sections. At this point, they just aren’t attractive anymore. Is there a way to bring them back, or should I start over?

These succulent plants are native to Africa and the Middle East, yet most aloe species flourish in our desert climate. Many are clumping types that produce new clusters on the outside, causing the original planting to expand its borders. As they grow and mature, older plants can turn brown. In some arrangements, aloes are meant to stand singly to show off their spiky shape. Whether you want a mass planting or a standalone plant, the solution to keeping them looking great is to divide them every three to five years. To do this, you can dig up the entire clump and break off a smaller section with roots and replant. Discard the rest or give them away. Alternatively, you can use a shovel to divide the aloes in the ground without digging up the entire mass. The best time of year to do this is in late spring, once they have finished flowering.

Art Holeman
Re-think shearing shrubs into balls, squares or cupcake shapes

Drive down any neighborhood street, and you will inevitably see front yards filled with manicured green blobs, which are the result of excessive pruning that removes the natural shape, flowers and beauty of shrubs. This style of pruning became popular during the Victorian era in the late 1800s and is still prevalent in the Southwest. It is the default maintenance practice of many landscape professionals and homeowners. 

However, this trimming method is unhealthy for plants, as it constantly strips away the foliage they need to make food and energy for survival. The result is a shrub with a thin outer green layer and a dense interior where sunlight cannot penetrate. Over time, areas will turn brown and die off, shortening the plant’s lifespan. Frequent pruning also causes plants to use more water as they struggle to regrow their leaves when compared to a shrub that is pruned twice a year or less.

So what can we do to avoid this outdated maintenance practice? First, allow shrubs to grow to their mature size where they will add texture and interest to the landscape. A bonus is that you will get more flowers, adding welcome color around your home. 

But what if you have a landscape filled with formally shaped shrubs? In most cases, you can revert them to their original form. To do this, severe pruning is needed, which involves cutting back to approximately 1 foot from the ground in the spring. In healthy plants, this will stimulate new growth within a few weeks. Older plantings, or those in poor health, may not grow back. In this case, you can replace them with a new one. 

Pruning shrubs every year is not necessary if there is room for them to grow. To ensure your plants have room to spread out, check out the Arizona Municipal Water Users Association at amwua.org/plants, a good resource for this information. If shrubs are too close together, you may need to remove some or switch them out for smaller ones.

Finally, how do you ensure your landscaper does not shear shrubs during each visit? Take them off autopilot and stress that you don’t want your plants sheared unless you specifically direct them to do so. Then, instruct them to prune your shrubs when needed in spring and how much to cut off.

I encourage you to begin this year with pruning less. You’ll have healthier and more attractive plants and save time and money.

Last year, our tree had a bumper crop of oranges. But some years, very little fruit is produced. Is there anything I can do to ensure that I will have plenty of citrus on my tree next winter?

It is common to experience a bountiful harvest one year while the subsequent harvest is disappointing. Citrus are “alternate bearing,” meaning that years when they are heavy with fruit are often followed with one where a lighter yield is produced. Understandably, this can lead to the belief that something is wrong when you experience less fruit production. Environmental factors, such as extreme temperatures and water availability, can also affect the amount of citrus that forms. Make sure that you are irrigating to a depth of at least 2 feet each time you water. According to the University of Arizona Cooperative Extension, orange and lemon trees should be fed three times a year, in January/February, March/April and in May/June, using a citrus food fertilizer, which aids in maximum production.

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