The time has finally arrived!  Summer temperatures are but a memory and fall is here! 

Every year we wait for the end of summer so we can start adding plants in the garden. The only question is what plants will I add?

The possibilities are endless…    
                                                                                                                           

Purple Lilac Vine (Hardenbergia violaceae)

The signs that fall in the desert may not be as evident as in other parts of the county, yet they are here.  Elongating shadows, cooler evening temperatures along with increased plant growth and flowering are clear signs that the heat of summer is fading and cooler temperatures are on their way.

Blackfoot Daisy  (Melampodium leucanthum)

October and November are the best months in which to plant most types of plants in the desert.  The reason for this is that plants use the cooler weather in which to grow a healthy root system so that by the time that the summer arrives, they are ready to handle the stress of the intense heat. 

Parry’s Penstemon  (Penstemon parryi)
Most trees, shrubs, perennials, and succulents can be planted now.  Stay away from planting palms, bougainvillea, lantana and other plants that suffer frost damage during the winter months.  They do best when planted in the spring.
 
Chaparral Sage   (Salvia clevelandii)
As in all climates, be sure to plant correctly.  Dig a hole three times as wide as the root ball but no more profound than the root ball.  This will allow the roots to grow outwards more quickly.  
 
When growing native plants, you do not need to add any amendments to the hole as this can cause the roots to just stay in place, enjoying the nutrient-rich soil, instead of venturing out into the regular soil.  If you do decide to add amendments to the soil, be sure to incorporate them well with the existing soil.   
 
Newly installed plants will initially require more water than established plants, so be sure to adjust your watering schedule accordingly.
 
Bower Vine (Pandorea jasminoides)

 So visit your local nursery and get planting! 


Globe mallow (Sphaeralcea ambigua) brings a unique “cottage-garden” feel to the desert plant palette along with some surprises. In spring a flush of beautiful flowers are produced that will cause people to stop in their tracks. After that, globe mallow will bloom off and on throughout the summer and fall.  
 

This shrubby, perennial is native to the Southwestern areas of North America where it is found growing along washes and rocky slopes. They grow quickly and reach approximately 3 ft. X 3 ft. in size. Globe mallow is cold hardy to about 20 degrees F.

Although most globe mallow plants produce orange flowers, they are available in other colors including pink, purple, white, red and shades in between. At the nursery, you will usually see the orange flowered variety available. However, some growers are beginning to stock selections of globe mallow in different colors. But buyer beware; unless specially marked or blooming, you don’t know exactly what color flower you will end up with make sure if you want a certain color to check for mark.  
 

Often, the surprise occurs after you plant them and wait to see what color the flowers will be. I bought four globe mallow, out of bloom, for my garden and ended up with one red, two pink and one white. For those who do not like surprises in the garden, you can wait and buy them in bloom in the spring.

USES: Globe mallow attracts hummingbirds as well as butterflies. They serve as a colorful backdrop for small perennials or small cacti. Consider planting with any of the following plants for a colorful desert flower garden – penstemon, desert marigold, ruellia, and blackfoot daisy. This beautiful but tough plant does best in full sun and performs well in areas with hot, reflected heat. Do not plant in shady areas as this will cause them to grow leggy.

Globe mallow do self-seed, and the seedlings can be moved and transplanted in the fall if desired. They are used frequently for re-vegetation purposes because they grow readily from seed.

MAINTENANCE: This pretty perennial is very low-maintenance.  No fertilizer or amendments to the soil are required. Prune once a year to approximately 6 inches to 1 ft. after it has finished blooming in late spring/early summer, which will help to prevent them from self-seeding, maximize future blooming and minimize unproductive, woody growth. Globe mallow is not the type of plant to repeatedly shear into a formal shape. When pruning, wear gloves and long sleeves since the tiny hairs on the leaves can be irritating to some as well as an eye irritant.

Once established, globe mallow is quite drought-tolerant, but will require supplemental irrigation for the best appearance and flowering. My globe mallow plants are connected to my drip-irrigation system and do very well when watered three to four times a month, spring through fall.

ADDITIONAL FACTS: Historically, globe mallow were used by Native Americans for medicinal purposes such as treating diarrhea, sore throats, eye diseases as well as skin disorders. Their roots were used for upset stomachs and poultices were made for treating swollen joints and broken bones.

*Have you ever grown globe mallow?

SaveSave

SaveSave

SaveSave


Do you like prickly cactus?  

I have a few favorites, one being santa-rita prickly pear (Opuntia violaceae var. santa rita). The color contrast of their blue-grey pads and the shades of purple are so striking in the landscape.  

This cactus makes a beautiful accent plant for the landscape. Both the pads and fruit are edible, (but you might want to remove the spines first ;-). Cold temperature and drought intensify the purple color.

Santa-rita prickly pear is native to the Southwest regions of North America. They can grow as large as 6 ft. X 6 ft., but can be pruned to maintain a smaller size.  Pruning is done carefully, by making pruning cuts at the junction where the pads connect.


Lovely yellow flowers appear in spring followed by red fruit in the summer months.  Javelina, rabbits and pack rats will sometimes eat the pads. Pack rats use the pads to make their homes.

The pads of the prickly pear are covered with clusters of 2″ spines as well as tiny spines known as glochids. Glochids are incredibly irritating to the skin and detach from the pad very easily. Their tips have a small barb, which makes them difficult to remove from your skin.  If you need to handle them, use a few layers of newspaper or a piece of carpet. Do not make the mistake of touching the pads with gloves because the glochids will attach to your gloves and render them useless, (I ruined a perfectly good pair this way). 
 
 **There are different ways to remove these small spines, including applying Elmer’s glue (letting it dry and then pulling them off), but many people have reported greater success using duct tape. 

 

 
USES: In addition to serving as an accent plant in the landscape, this prickly pear species can also be used as a screen. Some may be surprised to learn that they also make excellent container plants, just make sure they are not near any foot traffic areas. They do well in full sun or light shade in well-drained soil.
 
MAINTENANCE: Prickly pear is very low-maintenance plants. I always use tongs to pick up the pads that I have pruned, or you can use newspaper.  
 
Although they are incredibly drought-tolerant, watering once a month during the hot summer months, in the absence of rain, will be appreciated and will improve the appearance of your prickly pear. Shriveled pads indicate acute drought-stress.
 
 

Many people believe that the appearance of white, cotton-like areas on the pads is a sign of a fungal infection. However, it is caused by a small insect that secretes the white cottony mass, called cochineal scale.  Control is straightforward – simply spray off it with a strong jet of water from the hose – that’s it!

 
PROPAGATION: Prickly pear can be planted from seed, but there is a much easier way. Just cut off a pad that is at least 6 inches tall. Put the pad upright, in a shady, dry place for at least about two weeks. This allows a callus to form at the bottom.  
 
Plant with the cut end down, do not water for the first month because the bottom is susceptible to fungal infections. After the first month, water every 2 – 3 weeks until established.  If planted in the summer, provide shade until established (about three months). *I generally do not recommend planting in the winter but encourage waiting until spring when the soil warms up. 
 
If you have a large prickly pear, you can prune it, or you can start over by taking it out and cutting off some of the pads and plant them in the same place. Many of my clients have done this and been happy with the results.
 
INTERESTING HISTORICAL FACT: The Aztecs would cultivate prickly pear cactus infected with cochineal scale because the insects secrete a dark red dye with crushed. This was used to dye cloth. The Spanish exported this dye from Mexico back to Europe where it was used to dye royal garments and British military uniforms. The dye was highly valued by the Spanish, next to gold and silver. It takes 70,000 insects to produce 1 pound of dye.
 
*This is but one of many beautiful prickly pear species available to the home gardener.   Do you have a favorite species of prickly pear cactus?
 
 There are some signs that summer is beginning to fade and that fall is around the corner.  The stress that the high temperatures of summer bring has caused many plants to slow down their growth.  
 
However, the slightly lower temperatures in September bring on a flush of new growth for many trees, shrubs, and succulents in the garden.  I enjoy being out in my garden this time of year and seeing many of my plants rejuvenated.
 

With the somewhat cooler temperatures, I am now seeing many gardeners venturing outside and taking stock of the condition of their landscape.  Fall is a busy time in the desert garden because it is the ideal time to install many types of plants, which will be discussed in a separate post in early October.

  
SHRUBS: I just finished lightly pruning my ‘Rio Bravo’ sage (Leucophyllum langmaniae).  Summer flowering shrubs that are cold-hardy look their best when lightly pruned at this time to help reign in rangy, sprawling growth. This should be only done with hand pruners only.  Do not use a hedge trimmer and shear your shrubs.  They should have a pleasing natural shape when you are finished.  Do not prune back frost-sensitive plants at this time.
 
 ANNUALS:  Although the local nurseries are abundant with winter annuals, I don’t recommend planting them now.  The temperatures are still quite hot, and there is a good chance that they will not make it.  
 

In the past when mid-September came, I would load up the truck with 100+ flats of annuals to plant around the community where I worked as the horticulturist.   I would then spent the next four weeks making repeated trips to the nursery to replace dead plants that just could not handle the heat of early fall.  From then on I would wait until October to change out summer annuals and replace with winter annuals.  As a result, we suffered very little plant loss.

TREES:  Mesquite and Palo Verde trees that are overgrown can be lightly easily pruned back.  Resist the temptation to heavily prune at this time.  January and February is the time for heavy pruning to occur for these trees.
 
SUCCULENTS:  Cacti, agaves and other succulent plants do best when planted when soil temperatures are warm, which makes September a great time to install them before cooler temperatures arrive.   Prickly Pear cactus can be pruned back this month if needed.  Problems with agave may show up this time of year. 
 
If your agave suddenly collapses, there is a good chance that they have gotten an infection with agave snout weevil.  There is no cure and the agave should be removed, it will be smelly due to the decay the weevil causes – and not just a little stinky.
 
One of my (least) favorite memories happened years ago when I worked as a horticulturist on a golf course.  One year, we had to remove countless agaves throughout the landscapes due to a large infestation – the smell was awful.  If this happens to your agave, do not plant another agave in the area – use another type of plant instead.
 
ROSES:  Roses should be lightly pruned and fertilized this month (see earlier post for details).
 

CITRUS:  Make sure to fertilize your citrus trees if you have not already done so (see earlier post for details).

 
NEXT MONTH – get ready for planting and wildflower garden preparation!
Blue Palo Verde (Parkinsonia florida)

When people think of the Sonoran desert, hillsides studded with saguaro cactus and cholla often come to mind.   But interspersed between the cactus, you will find the iconic palo verde trees with their beautiful green trunks and branches.

The word “Palo Verde” means “green stick” in Spanish, referring to their green trunk, which is a survival mechanism in response to drought.  
 
Palo verde trees are “drought deciduous,” which means that they will drop their leaves in response to a drought situation.  Their green trunks and branches can carry on photosynthesis, even in the absence of leaves. 

‘Desert Museum’ Palo Verde (Parkinsonia hybrid ‘Desert Museum’)

Palo verde trees act as a “nurse plant” to young saguaro cacti by protecting them from the cold in the winter and from the intense sun in the summer.  Beautiful, yellow flowers are the product in the spring.    

  ‘Desert Museum’ Flower
There are three species of palo verde that are native to the desert Southwest; blue palo verde (Parkinsonia florida), formerly (Cercidium floridum), foothill palo verde (Parkinsonia microphylla), formerly (Cercidium microphyllum) and ‘desert museum’ palo verde (Parkinsonia x ‘Desert Museum’)
 

Another species of palo verde that is prevalent in the landscape are called palo brea (Parkinsonia praecox), formerly (Cercidium praecox).  They have a dusty green trunk and branches that twist and turn.  Their cold hardiness range is around 15 to 20 degrees F.

Palo Brea
PALO VERDE USES: Palo verde trees serve as beautiful specimen trees where their green trunks, branch structure, and flowers serve as an attractive focal point in the landscape.  They are drought tolerant, once established and provide lovely filtered shade year-round.  
 
When deciding where to place your tree, be sure to take into account that they need a lot of room to grow, mature sizes are listed below.  
 
Palo Verdes don’t do well when planted in grass and will decline over time.  Locate away from swimming pools due to flower litter in the spring.
Because of their more massive thorns and branching tendency to point downwards, palo brea trees aren’t recommended in areas close to foot traffic.  
  
Mature Sizes:
Blue Palo Verde – 30 ft x 30 ft
‘Desert Museum’ Palo Verde – 30 ft high x 40 ft wide
Palo Brea – 30 ft x 25 ft
Foothills Palo Verde – 20 ft x 20 ft
As with many desert trees, Palo Verde trees have thorns, except for the ‘Desert Museum’ Palo Verde.  

Foothills Palo Verde
PALO VERDE MAINTENANCE:  Prune to elevate the canopy and maintain good structure.  Avoid hedging and “topping” trees as this stimulates excess, weak growth.
 
MY FAVORITE: As a landscape manager, horticulturist and arborist, I have grown and maintained all of the palo verde species mentioned, and I truly enjoy them all.  However, at home, I have 4 ‘Desert Museum’ trees.  In comparison to the other species, their trunks are a deeper green; they produce larger flowers, are thornless and grow very quickly in the desert.  Also, they require little, if any, tree staking when planted. 

The blooming of my desert willow tree (Chilopsis linearis), is beginning to slow down.  The leaves will fall in December.  However, there were a few lovely pink flowers left.

Also, the recent monsoon storms have caused my ‘Rio Bravo’ sage, (Leucophyllum langmaniae), to burst out in flower.

Beautiful, magenta brachts surrounding the tiny, cream-colored flowers on my single bougainvillea shrub.

I also love the multi-colored blooms of my lantana ‘Patriot Desert Sunset.’  They will soon stop blooming for the winter.

The vibrant colors of my red bird-of-paradise, (Caesalpinia pulcherrima) add vibrant color to my garden and nectar for hummingbirds.  


In another month, many of these flowers will no longer be flowering, but until then, I’ll enjoy the view.

This beautiful plant is one of my favorite shrubs in the garden – so much so, that I have three.  Yellow bells produce bell-shaped flowers beginning in spring and lasting through the fall months until the first frost.
 
 Hummingbirds and butterflies are attracted to the flowers.  The vibrant green foliage and colorful flowers make this shrub a welcome addition to any desert landscape. 

Yellow Bells is a large shrub that grows to a height of 4 – 8 ft. and spreads 3 – 8 ft. wide.  You can find its native habitat in the Americas.  There are two different types; Tecoma stans angustata and Tecoma stans stans.  Visually, the most significant difference is in the shape of the leaves.  Tecoma stans stans had a broader leaf and are pictured above and below.

USES:

Because of its size, this large shrub makes a great backdrop plant.  I have used it to screen fences, sheds and also planted it up against the house.  Yellow Bells works well as a tall, naturally-shaped hedge.  This shrub thrives in full sun to filtered shade.  They do best in warm-winter areas but can be successful as a summer annual in colder regions.

MAINTENANCE:

This shrub is relatively low-maintenance.  It will freeze back in the winter months when temperatures go below 28 degrees F.  Since it blooms on current season’s growth, all that is required is to prune back the frost damage in early spring.  Seed pods are produced and can be removed if desired, which will extend the bloom period and improve the appearance, (the seed pods do not bother me, and I do not remove mine).   After an initial application of slow-release fertilizer when planting Yellow Bells, I have not needed to fertilize further. 

**Occasionally, caterpillars will appear but can be easily removed by spraying some BT (Bacillus thuringiensis) which is an organic pesticide.

 
 

COMMON NAMES: 

There are many familiar names for these beautiful shrubs.  Tecoma stans angustata is native to the Southwestern US and northern Mexico and goes by the names Arizona yellow bells, yellow bells, and yellow trumpet bush. 
 
Tecoma stans stans are native to Florida, the Caribbean and parts of South America and also goes by the name of yellow bells and sometimes yellow elder.  Because of the overlap of familiar names, be sure to purchase plants based on their scientific name.

I just had to share this photo of my flowering Arizona fishhook cactus(Mammillaria grahamii) also known as (Mammillaria microcarpa).

While walking outside in the garden this morning, I caught a glimpse of pink off in the distance. As I went over to explore further, I noticed my little Arizona fishhook cactus in full bloom. I don’t have many cacti in my garden, but even if I did, this little one would probably still be my favorite. 

Pink crowns of flowers appear off an on throughout the summer months in response to rain much to the delight of native bees.

I found this little cactus growing alongside a large boulder in an area of desert that was getting ready to be graded for a new house. At the time my crew and I were digging up different types of cacti, like barrel cacti and teddy bear cholla, to relocate them around the site out of harm’s way. I received permission to keep this little one.

One of the things that I love about this little cactus is it flowers off and on during the summer months in response to rain or a small amount of water from my garden hose.

Look closely at the spines, you can see where it gets its common name with their fishhook shape.

Believe it or not, I can hold this cactus (carefully) without getting pricked.

During the rest of the year, this small cactus fades into the background and is hard to see.  You can find it growing underneath bursage shrubs throughout the desert.

Do you have a favorite flowering cactus in your garden?