Dietes bicolor, Dietes iridioides, Dietes grandiflora
While much confusion exists about the common name, the three featured plants are essentially the same but with variations in flower size and flower color. A number of years ago, Dietes was thought to be part of the genus Moraea; in fact my ancient copy of Sunset Western Garden Book (1977) lists ‘Fortnight Lily’ (and its cousins) among the Moraea. The two genuses were eventually separated mostly because Dietes grows from a rhizome and Moraea from a corm. In botany, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes. Another example of a rhizome is ginger root, available at most grocery stores. Corms, sometimes confused with true bulbs, are short, vertical, swollen, underground plant stems that serve as water/nutrient storage vessels to help plants survive drought, heat and/or winter.
What I planted in early June of this year is Dietes bicolor (‘Butterfly Iris’). Dietes is Greek for “with two relatives” in reference to the dual relationship to Iris and Moraea; obviously, bicolor means having two colors. Dietes is a member of the family Iridaceae.
Before I discuss caring for Dietes, I want to elaborate on how to identify one species from the next. Keep in mind that growers and therefore nurseries are somewhat cavalier about which common name they pair up with which botanical name when they label them.
Dietes bicolor (‘Butterfly Iris,’ ‘Yellow Wild Iris,’ ‘Peacock Flower’) has cream or yellow flowers.
Dietes grandiflora and Dietes iridioides both have white flowers marked with yellow and violet; appear similar in photographs, but they are quite different:
D. grandiflora (‘Wild Iris,’ ‘Large Wild Iris,’ ‘Fairy Iris’) flowers are much larger, last three days, and have dark spots at the base of the outer tepals; the plant is larger overall.
D. iridioides (‘Fortnight Lily,’ ‘Wild Iris,’ ‘African Iris,’ ‘Cape Iris,’ ‘Morea Iris’) flowers are small, last only one day, and lack the spots.
Actually, I do have one more topic (can you spell r – a – n – t) before I proceed with Butterfly Iris. I mentioned a few weeks ago that watering issues might prove to be a life-long challenge for me; I think some previous posts have affirmed this. Here’s another example. About 10 days ago I noticed my three Butterfly Iris (according to Ms. Language-Person, the plural of Iris, the plant, can either be Iris or Irises) were doing rather poorly. For that matter, my Society Garlic wasn’t looking too hot either. All in all, the other shrubs were doing fine, so it pretty much had to be Pests or Irrigation (bugs or water). I examined plants for insects and found none…ergo, a watering problem. I thought about this quite a bit and then wandered to a somewhat related subject. I began to wonder why it was that:
(1) Plants for sale at Las Vegas nurseries look happy/healthy and my same plants were “looking like crap.” I’ll explain quotation mark momentarily.
(2) A very significant percentage of shrubs at these same nurseries reside under polyethylene shade cloth or lattice structures, including those labeled FULL SUN.
Here’s today’s geography lesson. Las Vegas is situated in the Mojave Desert, surrounded by dry mountains with undeveloped areas dominated by desert vegetation and limited wildlife. City elevation is around 2,030 ft above sea level. Much of the landscape is rocky and dusty. Las Vegas’ climate is an arid, desert climate; averages about 300 sunny days per year and more than 3800 hours of sunshine; averages about 4.2 inches of rainfall, occurring on an average of 29 days per year; snowfall is rare but possible. Las Vegas shares Koppen climate classification (can you dig THAT?) with Yuma, Arizona, Mexicali, Mexico and Dubai, UAE!!!
Now let’s explore the plants at Las Vegas nurseries. With a small handful of exceptions, the plants they sell are not native to the Mojave Desert. Rather, they come from other locales like California. So what does that mean? It means many plants which flourish in places like Azusa, California, with an average high in July of 89°, have adapted (somewhat) to the Las Vegas desert climate. The nurseries know this and prefer to keep most of their inventory in partial shade so plants stay vibrant and people want to buy them. Trust me. You certainly would not buy my Butterfly Iris in its present condition.
OK, so what’s the problem with my Iris? I took a field trip to one of my favorite nurseries to find out. I posed the question from (1) above and was told I wasn’t giving the Dietes enough water (AAUGH!!!) and when I told him I had one drip emitter per plant, he (somewhat sarcastically) rebuked me and said I should have three emitters for each plant. Oddly enough, another guy at the same nursery but in the sprinkler department said two was enough…I went with two per plant, at least for now. I’ll report at a later date if/when my plants recover.
Before everyone reading this falls asleep, let’s recap lessons learned. First, never forget it’s a desert out there! Second, if a plant needs more water to thrive (not just survive), don’t assume you need to run your sprinklers longer; perhaps more emitters is the answer.
Once again I feel I must rush through the “care and feeding” part of my discourse but at least Dietes is pretty simple. AHS Encyclopedia says to grow in “moist but well-drained soil.” The University of Florida (!!) Cooperative Extension recommends “Plants in the full sun appear to do best with frequent irrigation…Plants grow…in standing water, making it ideal for water gardens and wet soil.” Hmmmmmm. An all-purpose fertilizer while blooming will improve overall appearance and health of plant. No pests to speak of and disease is all but non-existent if soil drains well. Average winter tolerance of the three species is to 20°. Pruning isn’t needed except to cut out dead leaves. Do not remove flower stalks of D. iridioides; they can bloom for years. If you want additional plants for your garden or for friends, lift the plant and divide the rhizome…no more frequently than every three years.
- RIP Wally. He made a valiant effort but succumbed to our record-breaking high temperatures this past July.
- I named the African Sumac, “Simba.” If I have to explain that, please unsubscribe to my blog.