Most people are drawn to blue flowers, so it’s not surprising they’re really popular Phoenix landscaping plants. Anything that produces blue to blue-purple blooms is usually the first thing to sell out in a nursery, because the majority of plants bloom in any color but blue. While the ‘true blue’ flower is a rare thing to see, these are really close, and put on a beautiful show in the yard. We’ve picked plants that perform well here in the Phoenix and Scottsdale climate.
1) Vitex agnus-castus
Commonly known as the Lilac Chaste Tree, this rugged small multi-stemmed tree can also be maintained as a large shrub. Blooming in May to June here in the Phoenix – Scottsdale area, it makes a striking statement in early summer.
This plant can grow to 25′ tall by 20′ wide, but is easily maintained smaller with proper pruning. You can also extend that wonderful blue blooming by removing spent flower heads regularly, perhaps as long as into early fall.
It is deciduous, so be prepared for its bare branches over winter. Some people don’t like this plant because it isn’t evergreen, but when placed well it’s leafless season make it architectural interest, especially if it’s shape is maintained.
2) Solanum crispum
The Blue Potato Vine is an outstanding plant for covering fences and walls around your courtyard or patio. A native of Chile, it is right at home here in the Phoenix – Scottsdale area, and a welcome way to soften privacy walls or enclosures.
This semi-evergreen climber can grow to 20′ tall, and gives you tons of lovely blue blooms from midsummer through fall. You won’t have to wait long for it to grow larger after planting, it is pretty fast growing.
The best placement in your landscaping is on a wall that faces south or west to protect it from frost damage. It’s not the frost that harms the leaves and stems, but the flash frying action of sun hitting all those little ice crystals. When protected from morning sun completely, the frost will melt long before harm can be done to the plant.
A favorite with homeowners across it’s hardiness range, Sage, as most people refer to it gives you an easy to maintain medium-sized shrub that looks great in any style of landscaping. They are xeriscape tolerant, and looks great year around, plus it does not require pruning or shearing to keep it looking good. Plant in full sun for best flowering and plant density.
There is more than one species in this family of plants that shine in the climate of Phoenix and Scottsdale: Texas Sage (L. frutescens) has very silvery leaves and matures to about 8′ tall. While it can be sheared, it is beautiful in its natural shape. Chihuahuan Sage (L. laevigatum) has greener leaves and is a bit smaller growing at 4-6′ high and wide. Some of the variations include named varieties, Heavenly Cloud, and Green Cloud.
4) Duranta erecta
Graceful, cascading flower sprays cover the new growth of the Skyflower; a very appropriate common name for this rugged native of Mexico. This large, sprawling shrub can also be trained into a tree-form. A fast-grower that matures to 20′ high and wide, but you can keep it smaller with pruning.
The flowering is profuse from late spring into summer, followed by ornamental berries. Several cultivars available with blooms in a range of light blue to rich lavender. Best flowering is in full sun. The birds love the ornamental berries that follow the flowers, and make quite a nice contrast of colors in the landscape. The fruits are poisonous to mammals, including people. Plant it away from where young children play unattended.
5) Ruella peninsularis
Known as Desert Ruella, this handsome shrub is a great addition to your Scottsdale or Phoenix xeriscaping. It’s a native of southern California, so is perfectly at home in a dry location. The shrub is on the smaller side, maturing to 4-6′ high and wide. You can shear it, but be sure to do so after flowering is fully finished, or you won’t have much blue color.
The blooms look very similar to a petunia, but this isn’t the same as a Mexican Petunia, which is actually a perennial, not a bush with woody stems. The blue-purple flowers top off the attractive foliage from late spring through early summer. For great blooming, it needs to be in full sun, which may mean you do need to give it a little water regularly during the hot season. Ignoring the minimal needs for moisture assistance in desert landscaping plants gives you scraggly plants, instead of lovely specimens.
6) Plumbago auriculata
While Cape Plumbago is not a plant for formal sheared shaping, it has many attractive uses in Valley landscaping. A vigorous grower that is out of place in the wrong spot, hedging it means losing all or most of the pale blue blooms. It can be trimmed a bit, when done selectively and maintain that lovely flower show very nicely.
This shrub has a really long bloom season – from March through December. It has a sprawling habit, and can grow up to 6′ high and 10′ wide. To truly enjoy this plant, give good thought to where you place it in the landscaping. It will handle full sun, but your flowers will fade a lot in the hot season. Also, for the best blooming it prefers a dry location. Too much water makes it grow leaves, not blossoms. The key to successfully avoiding both of these known issues is to plant it where only morning sun touches it. Don’t put it in all shade though, because then you’ll have no flowers at all.
First image courtesy of gailhampshire, CCby2.0.