Yucca plants flower more than once in their lifetime, while Agave (century plants) flower once and then die. But do yucca flower every year? Plantsman extrodinaire Jan Emming is the author of this post on yucca flowers. (edited slightly.)
Yucca Flower Cycles
“Most yuccas skip anywhere from 2 to 4 years in between flowerings on individual heads. This is because yucca die just a little when they flower. Technically, the terminal growth points of yuccas die during the process of blooming. Thus they need to develop new side shoots in order to resume growth and eventually flower again. Typically those new heads have to grow for at least one full season before flowering again, and many of the slower growing yucca require several years.
The act of flowering often encourages branching, but not always. Some faster-growing “tropical yuccas” (from warm and wet climates) can flower almost annually out of their new heads. Most of the slower-growing “desert yuccas” (dry climates) take a minimum of 2 years, and many take 4 to 5 years to bloom again.
While a given head might not flower again for 2-4 years that doesn’t mean another head or branch elsewhere on the plant (if it has them) can’t bloom the next year if it’s large enough to do so. Thus, many yucca clumps or multi-branched specimens might flower annually, albeit on different stems or heads from the prior year. Yucca blossoms are edible, and we will post on one way to use them on Savor the Southwest.
Monocots Are Different
Compare this terminal flowering pattern of yuccas to that of other monocots. For example the African aloes produce flower spikes out of side buds, a cellular division process that does not kill the terminal growth point. This means that aloes can easily bloom annually, and many species can readily produce multiple flower spikes per year, whether in sequence or all at once, because they don’t need to replace their growth tips. They are using lateral side buds, a process called axial flowering. (More on growing aloes – here)
By contrast agaves also flower terminally, but almost all species (with only a handful of exceptions) die after flowering and setting seed. While many agaves have pups that continue to grow after the main mother rosette dies, once a given rosette blooms that is it and that particular head will not continue to survive even if it has pups surrounding it that might replace it over time. This single-time flowering habit is called monocarpic. [[see below]] While many agaves do produce side pups before doing their final blooming as a reproductive hedge against complete seed reliance only. But many do not pup and are solitary rosettes that rely entirely upon seed reproduction alone.
There are also tropical monocots worth mentioning in this discussion. The Bromeliad (pineapple and also airplant) family has members that exhibit both types of blooming characteristics depending upon species. Some are monocarpic terminal bloomers where the flowering rosette dies afterwards, while others are polycarpic and flower more than once, like the yuccas do. Most bromeliad genera flower terminally like the yuccas, while others flower axially like the aloes.
Most palms are polycarpic and flower axially as well, but there are a few monocarpic palms that flower terminally and die after producing only one flower show in their entire lifetime.
I hope this will help readers understand the differences in growth habits and flowering patterns in the various monocot plants that might be in your garden or plant collection.”
Monocarpic Defined (Yucca are Polycarpic)
Monocarpic plants are those that flower, set seeds and then die. The antonym is polycarpic, a plant that flowers and sets seeds many times during its lifetime. Along with agave, there are a number of species of bamboo that are monocarpic, which is of concern when whole forests of bamboo all flower at once and die. You may have heard of this as a problem with panda survival – and it is of concern.
A monocarpic plant can live a number of years before it will flower. Flowering in some plants signals senescence (old age and death) while in others plants it is the production of fruits and seeds causes changes within the plants which lead to death. These changes are induced by chemicals that act as hormones, redirecting the resources of the plants from the roots and leaves to the production of fruits and or seeds.
Jan again: “Monocarpic flowering is found in many plants – including dicot plants. Some well-known examples are many annual plants which naturally survive only a few weeks or months, flower one time, and then die before a full year has passed. We usually call them annuals, but they are readily considered to be monocarpic even if they produce hundreds or thousands of flowers on numerous stems.
Monocarpic dicots that live for two years include certain garden vegetables such as beets and carrots. These usually live for two years, a lifestyle commonly called biennial. They live their first year as non-flowering plants, overwinter once, and then flower their second summer and die afterwards, making them monocarpic biennials. There are also monocarpic perennial dicots, such as certain succulents like hen-and-chicks which live for multiple years as leaf rosettes that do not flower, then bloom once and perish.”
All this botany too much? Don’t worry, most of my writing is not this technical. For example, have fun with this flowering monocot – and a cousin of yucca – the colorful canna! They bloom reliably all summer, every summer.
About our Guest
Jan Emming lives in the midst of the desert at “Forever Ranch and Gardens,” outside Yucca Arizona. His website is JanEmming.com
More about overall care of your land and landscape in this book: Month by Month Gardening for Arizona, Nevada, and New Mexico (Cool Springs Press). This link is to Amazon and if you buy the book there the Horticulture Therapy non-profit Tierra del Sol Institute will get a few pennies – at no extra cost to you.
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