Monthly Archives: October 2018

Help Your Christmas Cactus Bloom This Year

cropped-cropped-dscn05311.jpgWe’re sharing this post from 2016 again as a reminder that dark, cooler autumn nights are needed for Christmas Cactus to produce glorious blooms at the holidays. Given the right conditions now, you’ll enjoy beautiful flowers before too long. Read on for all the details!

Let me start by saying I’ve killed my share of houseplants, but one that has lived for close to three decades is the Zygocactus. Commercially, growers sell two slightly different plants as Zygocactus: the Thanksgiving cactus which has pointy edged branch segments and blooms around turkey time and the Christmas cactus which has rounded segments and blooms for its namesake. Care for the plants is essentially the same. Mine, shown above, is the Thanksgiving variety, Schlumbergera truncate.  Through periods of  neglect, inconsistent feeding and infrequent (twice maybe?) repotting, this plant keeps blooming prolifically year after year. I’ve rooted cuttings several times as gifts, but curiously, the offspring have rarely flowered in their new homes, where I might add, they get more TLC than they would living with me. This begs the question, what does this plant need to thrive and re-bloom? Here are the best tips from the experts and a few of my own observations.

  • It likes a bright, but not sunny location with temperatures that do not drop below 60 degrees.  Mine moves from indoors to an east facing screened porch from Memorial Day till Labor Day, or longer if the fall is mild like it was this year.
  •  It is a cactus which likes humidity. Unlike most cactus which prefer dry air, it hails from the tropical rainforests of South America and likes moist air. Sitting the plant on a pebble tray with water that does not touch the bottom of the pot can help, or living in a kitchen or bathroom would be ideal.
  •  It wants good drainage. If repotting, use standard, well draining potting soil. Water when it is dry just below the soil line, about once a week. I’ve  found  it amazingly forgiving if  when I forget to water. Over-watering will cause branches to rot, so more is not always better.
  • Spring and Summer are its active growth times. Prune when it is done blooming or in early summer to promote side branching. Cuttings can easily be rooted in water or soil. Adding houseplant food during the growth period helps. I have cut back branches to about six inches in the spring and the plant tripled in size by the end of the summer.
  • Here’s the key! It needs longer autumn nights to rebloom. Photoperiodism is a plant’s reaction to periods of light, similar to our circadian rhythm. Starting in mid to late September, the Zygocactus needs between nine and twelve hours of uninterrupted darkness each day in order to flower. Thanksgiving cactus take about six weeks of longer nights to sprout buds, Christmas cactus need about eight to twelve weeks.  This longer “sleep” period is the trickiest part of the reblooming process and why the porch, which is generally dark at night, works so well. Other options are to locate the plant in a similarly lit room, or  early each evening, cover it with a box or put it in a closet. Complete darkness insures maximum blooms. From experience, I’ve found that the occasional interruption of darkness reduces blooms, but will not thwart all flowers.
  • Stop the longer night process when buds emerge. The plant is now ready to flower. At this time, reduce watering slightly to promote brighter flower color.
  • Watch for bud drop. This could indicate you’ve reduced water too much. If the plant is new to you, it also could be reacting to a change in environment. Drafts or temperatures below 60 degrees may also be the culprit. I often see shriveled tiny buds at the end of the blooming cycle, as though the plant is  exhausted from the work it takes to flower for weeks on end. I found no science to support this notion, just my take on it!

Zygocactus are graceful, pretty plants, with or without blooms. Their showy, colorful holiday flowers are a beautiful treat at the end of the year. With a little extra care in the fall, they will regale you with splendid  holiday color.

Related posts:

Keeping the Ho Ho Ho in Holiday Plants

A Year in the Life of an Amaryllis

Text and Photo by Linda McDonnell, a Denver County Master Gardener

Tree of Heaven: Don’t Let the Name Fool You

Google Free ImageAilanthus altissima or Tree of Heaven, is a notorious, fast growing, invasive plant which left unchecked can quickly become a large shrub or substantial tree. An urban nuisance, you’ve likely seen it jumping out of cracks in sidewalks, pushing through established shrubs and lining alleys where little else will flourish. I recently found a seedling growing in the corner of my pebble-lined basement window well, a testament to its ability to survive in poor soil with little moisture.  It will grow most anywhere except very dense shade and swamps and is capable of choking out desirable plants, forming  thickets and damaging sewer lines or building foundations. The vigorous lateral root system sends up numerous suckers and the plant will also easily establish by seed. Remember the novel A Tree Grows in Brooklyn? The title’s tree is Tree of Heaven – aptly used as a metaphor for determination and survival.

In the late 1700’s the tree was brought to this country from China and was heralded for its rapid growth. According to the U.S. Forestry Service, a young specimen can grow 24′ in the first four years and a mature tree can easily reach 50’ or more and produce over 300,000 seeds annually.

Ailanthus altissima has several distinguishing characteristics detailed in this Colorado State University publication. Sometimes mistaken for Sumac, Tree of Heaven leaves are pinnately compound (made up of several elongated leaflets) with a glandular notched base and smooth edge. The smooth leaflet margins differentiate the plant from Sumac, which has a jagged leaf margin. When Tree of Heaven foliage is crushed it has a foul odor resembling rancid peanut butter, hence another common name, Stink Tree. Clusters of yellow-green flowers emerge in spring; later in the season, female plants produce tan to reddish, single-winged samaras or seed pods. Large triangular leaf scars are visible on the twigs and are another defining characteristic of this notorious plant.

To eliminate Tree of Heaven, vigilantly pull small seedlings by hand.  If the plant is well established, cutting it down will trigger the root system to produce an army of suckers, which in short order can result in a small colony. An effective treatment is to make numerous slashes on the trunk or drill holes into the bark and immediately apply a full strength herbicide containing Triclopyr on the openings. Waiting even longer than 30 seconds to apply the chemical renders the treatment ineffective, as the plant quickly seals the wound in the cambium layer and prevents the herbicide from reaching the root system. It can take multiple applications to kill a well established plant. As always, follow all instructions for the safe use of chemicals. Simply digging mature suckers up without the use of herbicide may be effective over time, but the bossy root system is likely to make this a frustrating and counterproductive exercise.

Additional Resources:

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410131.pdf

https://www.invasivespeciesinfo.gov/plants/treeheaven.shtml

https://articles.extension.org/pages/62664/ailanthus-altissima-tree-of-heaven

https://www.extension.iastate.edu/forestry/iowa_trees/trees/tree_of_heaven.html

Photo Credits:

Image 1 (seedling): Google Free Image

Image 2 (tree):  Annemarie Smith, ODNR Division of Forestry, Bugwood.org

Image 3 (flower): Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Image 4 (tree scar): Daniel Herms, The Ohio State University, Bugwood.org

Written by:

Linda McDonnell, a Denver County Master Gardener