Drought Tolerant and Dependable - Senna artemisioides - Silver Foliage too!

I love the silver foliage of Senna artemisioides! It is well known that this gorgeous foliage color is an evolved adaptation to withstand solar radiation and slow down transpiration. It is wonderful how silver is the perfect color to make all plant combinations sing! It combines well with everything. This "little black dress of plants", is the magic ingredient to make semi-arid gardens look like they make sense. Any flower color works with silver. Even with no flowers, some silver-foliaged punctuation among other green plants creates excitement and rhythm. It also visually cools the garden. Here is a garden photo from blogger Noelle Johnson www.azplantlady.com that illustrates what good blender silver foliage is in the landscape.

Noelle Johnson

Senna artemisioides is the plant in the rear of the foreground with cheery yellow flowers. The species name, "artemisioides" reminds us that this plant looks similar to Artemisia. Below is a closeup of the flowers and feathery foliage, which is the inspiration for its common name, Feathery Cassia. What looks like leaves are actually another drought adaptation, and are actually flattened leaf petioles. Once in awhile, you will see a remnant of a leaf. This plant blooms in late winter/early spring for several weeks. Later, it can throw out a few blooms if it is not too hot. It is always an early treat to see it blooming, and I never water it. I have it planted in well-drained sandy loam soil in full sun. This plant really does well with heat, so feel free to place it next to a sidewalk or wall. 

Pretty against a blue wall                                                                                                                           S. Reeve

The plant originally comes from the MacDonnell Ranges just west of Alice Springs in the Northern Territory of central Australia. Flowers are followed by flattened green seed pods that look like flat edamame. They look like pea pods because they are a legume, and also a member of the Fabaceae Family. Senna is also a member of the Fabaceae sub-family, Faboideae characterized by having bilaterally symmetrical (zygomorphic) five-petaled flowers with fused or connate stamens. These pods eventually dry brown. If you find them unattractive you can trim them back after flowering and you can also take the opportunity to keep this shrub under its 6-8 foot height and width. It trims easily and remains neat in the landscape. This plant blooms on old wood, so do not wait to prune it. Combine this plant with any selection of silver-foliaged Leucophyllum frutescens or blue-flowering Eremophila hygrophana for perfectly matched, and oh so satisfying, complementary colors. Add a grouping of Agave gemniflora, a Cercidium x 'Desert Museum" and a local boulder and you have a great combination! 

Senna artemisioides                                                                                                                                 S. Reeve

Here is a closeup of the fragrant five-petaled flowers, and the needle-like phyllodes that are 2-4 cm long or around 2 inches. The flowers of Senna like other members of the Fabaceae are frequently visited by native bumblebees. This plant is reportedly hardy to the low 20's and is deer resistant. It is best to grow this plant slowly. Do not fertilize. Water deeply and infrequently, or in my case, not at all. Overwatering can lead to root rot. Fertilizer and water will cause an unattractive droopy growth habit when the flowers are blooming. Naturally, the growth habit is rounded and attractive. Seeds can be collected and sown for propagation. Soak overnight in boiling water. Love this plant for its ease of care and naturally beautiful habit and because the bees love it too.

Join me for a talk on bulbs especially suited for San Diego gardens on Saturday, March 17th at 9 am

 

Join me for a talk on bulbs especially suited for San Diego gardens on Saturday, March 17th at 9 am http://www.mastergardenersd.org/seminar/

Metrosideros collina 'Springfire'

Metosideros collina 'Springfire' backlit by the sun                                          S. Reeve

I love hummingbirds, and I love that hummingbirds love this plant! Metrosideros collina 'Springfire' has been in a pot on my deck for five years now. It is thriving and just gets bigger and better every year. Right now it is loaded with coral-colored brushy blooms that draw hummingbirds like a magnet. I watch from my kitchen sink as they go from flower to flower. This plant gets serious and long (by hummingbird standards) attention from the flying gems. Surprisingly, honey bees visit it too. Initially, this shrub was reported to get 6-8 feet tall, but reports from gardeners that have been growing it for some time say it will get much bigger. San Marcos Growers says 25 feet eventually! Quite a difference! My travels have taken me to New Zealand to see another Metrosideros species, Metrosideros excelsa, the New Zealand Christmas tree or Pohutukawa. I was completely taken with this plant and it became apparent after some observation that it grew best right along the coast. Plant descriptions for Metrosideros collina say the plant grows best in coastal conditions as well, so I hesitated to try it since I live about twelve miles inland. My gardening location gets some coastal influence, but I wondered if it would be enough? Well, I can now suggest that Metrosideros can be grown a little inland and it does well and blooms fantastically! 

Honeycreeper on Metrosideros polymorpha                        Les Williams

I love to watch the flowers fiery glow in the sunlight that backlights them. Metrosideros collina is found from French Polynesia all the way to the Hawaiian Islands out in the middle of the Pacific Ocean. Endemic Hawaiian birds called honeycreepers pollinate them in Hawaii and hummingbirds love them here. Flowers last from two weeks to almost one month and bloom heaviest in January-February and throw out additional blooms almost year around. These long-stamened and long-styled flowers produce copious nectar for much of the life of the flower. Interestingly, studies show that smaller plants produce flowers with more nectar than flowers on mature plants. I guess they need a little help to get the bird traffic to come visit them! Metrosideros flowers resemble the brushy flowers of Callistemon because they are in the same family of Myrtaceae. 

Metrosideros collina 'Springfire' bloom                                                                                                 S. Reeve

                                                              
The foliage of this plant is a wonderful gray-green and the leaves are thick and coriaceous. They appear gray because of a light dusting of white that covers the leaves. I would have like to get a photo of a hummingbird on this plant but hasn't happened yet. Metrosideros foliage is hardy and healthy looking all of the time. My plant gets regular water and seems to thrive from the additional attention. I collect kitchen water and throw it on whichever plant strikes me as needing water. Because this guy is right outside my door he gets his fair share when I am too lazy to walk further. My life is certainly brightened by this wonderful plant.

Gardening in San Diego-This or That?

This is a photo of my garden in Athens, GA where I lived starting in the late 90s. I loved getting the chance to garden in the South. My career as a flight attendant brought me out to Atlanta originally, and school kept me there a little while longer. Words cannot express how much I loved that garden, the soil that I built, and all of the plants that flourished there. I miss it so much! In my mind, I can still walk around and look at the plants. As the saying goes, when the gardener leaves, the garden dies, and, unfortunately, it only exists now in history. I dearly miss the sweet little native spring ephemerals that started the gardening year, and the cherished, but loud, memory of the frog chorus in the springtime. The thing is I saw firsthand how camellias, azaleas, hydrangeas, magnolias, and other "Southern" plants grew and thrived on almost 60 inches of rain a year and deep acidic loamy soil. We had warm summer nights and sometimes 100% humidity!

Sharon's garden Athens, GA

And yes, I have seen some passable examples of Southern plants in San Diego but I shudder to think about the amount of water and changes to the soil that this illusion requires. Do I desire to grow the wonderful plants I grew in Georgia? No, not really, they exist only in my memory. It seems strange to me to try to recreate such lushness in such an alien arid environment. In Southern California, our alkaline soil, dry summer weather, lack of humidity, cool nights, irrigation water filled with salts make this climate so completely different, as to seem like another entire planet. No, gardening as I did in Georgia is only a historical point in time--never to be repeated. I have a fresh opportunity here to try a whole different way of gardening with a huge palette of plants I only imagined I would ever grow. It's funny how many California natives I tried to grow in Georgia with disastrous results because that is what I knew. It was only when I made the decision to work with what I had that the successes came. 

This is how I would like to garden now. The upper photo is a Michael Buckner garden in San Diego and I love the hot colors. The second photo is a Kate Frey garden in Northern California. I want something in between. I am so lucky to try to grow completely different plants in my garden. It sure is trial-and-error at this point and I am learning more with my failures than my successes. Do I want to try to recreate my Georgia garden as much as I loved the plants? No way. I love it here, but I sure do wish it would rain more. 

Justicia sericea 'Inca Queen'

Close up of hummingbird-attracting flowers

If you are looking for a great drought tolerant plant that stays green and looks super healthy all of the time, think about getting Justicia sericea. I am very impressed with the performance of this plant in my La Mesa garden. My garden is in USDA Hardiness Zone 10b, and I have well drained sandy loam soil. You probably know this, but I love hummingbirds! This Peru-native is a great hummingbird plant and it blooms almost non-stop in full sun. This, like many of my favorite plants, is in the Acanthaceae. Justicia is the largest genus in the Acanthaceae with 600 species from tropical areas in the world. This particular Justicia has anti-inflammatory properties. It was introduced by my friend Warren Roberts from UC Davis. It blooms more heavily in the cooler months, but still blooms in the summer. True red open tubular flowers that look made for hummingbird heads to slide into cover this plant most of the time. Flowers have an easily recognizable bilabial corolla with a three-lobed bottom lip and two stamens. You can see this in the photo. It barely gets water--ever. What is so impressive is how it looks in spite of no water. This non-woody shrub is lush-looking and maintains an almost surreal symmetry, even after five years. Its beautiful rounded form requires no trimming. I was going to go outside and get the dimensions for you, but it is dark out--oops, so I shall have to depend on my memory. It is approximately 3-4 feet across and 2.5 feet high. It is also so green and lush there is no "dead stuff" to prune out. Attractive bright red flowers never need deadheading, they self-clean and fall off with no lingering discolored aging blooms. You either see flawless blooms or no blooms at all, just pleasing opposite dark green elliptic foliage. I have never done anything to this plant except plant it. Now here's the weird part, for such a wonderful plant for Southern California, you would think it is in the Sunset Western Garden Book, but it's not! 

Justicea sericea 'Inca Queen'

It's a Winner Agastache for San Diego!

I love Agastaches but have not had much luck with them in a couple of places I have gardened. I didn't expect much with the new Agastache I tried, and have been very pleasantly surprised. Agastache 'Purple Haze' has grown well in La Mesa, CA. When I lived in Athens, GA the only one that worked was Agastache x 'Blue Fortune'. It was the only Agastache that tolerated clay soil and not the sharp draining soil that most Agastaches prefer. This was bred in Holland by Gert Fortgens of Arboretum Trompenburg. But compared to hot colors of western Agastaches, it was not satisfying. A fairly insipid blue actually. Agastache 'Blue Fortune' is a hybrid of two species, Agastache rugosa, from Korea, and Agastache foeniculum, from the US. While it was nice to grow ONE Agastache, I wanted more. 

Gardening in San Diego I thought would be a slam-dunk for Agastaches and I was so excited! Unfortunately, my trials with them have resulted in my thought that many of the hot-colored species need winter cold in order to thrive and come back. I have the well-drained sandy loam neutral soil that they like, but for some reason, they do not thrive. As I continue to learn I will certainly be updating with new information. I would like to try Mexican species as it would seem to me that they do not need as much cold. I know several of the hybrids that I lust after grow well north of us in Sonoma and are used to beautiful effect by Kate Frey in her wildlife gardens. Is it the increased winter chill or is it the additional precipitation? Only time and further experimentation will tell, and I am happy to be doing the research. Agastache 'Purple Haze' is also a hybrid of Agastache rugosa and Agastache foeniculum. This plant was bred by Coen Jansen who has a small nursery in the Netherlands. He breeds our prairie plants into exciting and tough hybrids, and then he sells them back to the US. The plant has been long-blooming for me. It started in the summer and is still throwing out blooms in February. I really like the color of the flowers. Photos do not do it justice. It is a much richer purple and it appears washed out in photos. The size of the plant has increased by about six times since I planted it a few months ago. The foliage is substantial and very healthy even crammed into a garden bed. No disease or insect problems of any kind. Such a robust plant! Here is a photo.