I’ll admit the title might be a little misleading. “Professionals” is a bit of an exaggeration because professionals have degrees in horticulture and greenhouses with temperature controls and light regulation that make fiddling with flower timing eerily precise. This post is filled with Barb’s at-home hacks for altering flower timing when you don’t have fancy equipment.
Healthy orchids tend to flower at the same time every year. It’s crazy, I know, but weirdly true. If you buy a flowering orchid in March and raise it well, it will most likely flower again the following March. However, you can fiddle with the timing a bit, particularly after the bud spike has begun growing.
Getting back to orchids, this temperature dependence is the same reason we can alter bud spike development by changing the temperature. Cooling your orchid down will slow down bud spike development because the chemical processes that need to happen to create the bud spike slow down. Conversely, increasing the air temperature will speed up those reactions and get your plant to flower faster. The key here is to make small changes. Nothing too crazy. Sudden, drastic temperature changes will overstress your plant, possibly to the point that it drops the bud spike entirely.
Speeding Up Flowering:
When it’s needed: If you need a plant to bloom earlier.
How it’s done: Barb had to do this recently because a plant she entered in the Philadelphia International Flower Show was not open the day before she had to take it down to Philly for judging.
The bud was nearly open, so to give it an extra nudge, Barb set the plant on a heating pad the night before. That photo on the right is what she woke up to the following morning! Some important things to point out: (1) The heating pad was on its lowest setting. The goal is just to warm up the plant a bit, not bake it. (2) The orchid is not sitting directly on top of the heating pad. Barb just flipped a dry tray upside down and set the pot on top. That way, she was only heating the air around the plant rather than cooking the pot and the roots. (3) This worked overnight because the bud was already very close to opening. Tighter buds and less developed bud spikes will require more time.
Slowing Down Flowering:
When it’s needed: If you have an orchid that is already flowering and you want to extend the life of those flowers. Or, if you want to slow down bud development to delay flowering.
How it’s done: To slow down flower development, just cool the plant down. Barb has a couple methods that she uses depending on how long she needs to stall development. For small changes, she just uses a bow window in her living room, pictured on the left. The glass surrounding the plant on three sides cools it down more overnight than sitting further away from the windows. Barb also turned a spare bedroom into another cool room for orchids. She partially closed the heating vents in this room and keeps the door shut so the room stays ~5F cooler than the rest of the house. The room still gets excellent evening sunshine. I’ll give you the same warning as with warming the plant up, you don’t want to make any drastic changes to temperature. Most orchids can stand temperatures down to ~50F, but they don’t like sudden changes, like from 70F to 50F in two minutes. If you are going to move an orchid to a cooler temperature, do it incrementally. For instance, Barb may inch a plant closer to her bow windows over the course of a couple days. Or she may leave the spare room’s door open to warm the room up before she moves the plant into the room. Then, she’ll slowly close the door to cool the room down while the orchid is in to allow the orchid to acclimate.
I don’t know about you, but twice a year, Day Light Savings always messes me up. For at least a week after we fall back or spring forward, I’m a wreck—I can’t focus, I’m more tired than usual.
Part of the problem is because that 1 measly hour change messes with the human body’s circadian rhythm. You may have heard of that term before, in Latin circadian roughly translates to “about day”, meaning this rhythm is about ~24hrs long.
Although we still don’t understand all of the details of circadian rhythms, here are some things we do know:
Circadian rhythm in plants:
The most visible way that plants demonstrate their circadian rhythm is by tracking the sun with their leaves or flowers. In fact, the first time this motion appeared in scientific reports was in the 1700s, so we’ve know about it for a while. Even today, we don’t understand exactly how plants control their circadian rhythm.
Sunflowers are excellent for observing this solar tracking. What’s absolutely wild about these flowers is that they reset themselves at night. They follow the sun from east to west during the day, but overnight they reset back to face east for the next sunrise. This demonstrates that, although they may follow the environmental cue of sunlight, that’s not the only driver. Without sunlight at night, they still somehow move back to face east (not south or north) and they are reset back to east before the sun rises again. Check out this video to watch sunflowers in action: https://www.nature.com/news/video-sunflowers-move-to-internal-rhythm-1.15548
Circadian rhythm in orchids:
The most obvious example of circadian rhythm in orchids that I’ve observed in my own plants is flower scent. Have you ever bought a plant that the grower swore smelled beautiful, but every time you smell it, there’s no scent? Try smelling that flower at different times of the day—including the middle of the night. The chemicals responsible for the scent are expensive for the orchid to make. Most orchids won’t waste the energy or resources to make those chemicals if their pollinator isn’t active. It’s like calling your night-owl friend at 6am. Why bother when you know she’ll be asleep and won’t answer? You have a better chance of her answering if you wait for a time when you know she’ll be awake.
For instance, I have an oncidium that only has a scent in early afternoon while my mom has a brassolaeliocattleya (Blc.) that has the most beautiful, powerful scent…at 2am. The difference is that my oncidium’s target pollinator is probably most active in the middle of the day, while the Blc.’s pollinator is likely nocturnal.
Biomes – an area of land with specific environmental conditions that is home to animals and plants adapted to those conditions
The greatest diversity of orchids are found in tropical and subtropical regions of the world. These are areas with a lot of rain and warm average annual temperatures. Epiphytic orchids are almost exclusively found in these biomes because their roots grow out into the air where they have no soil or media to moderate temperature or protect them from water loss. Meanwhile, cooler climates are home to terrestrial orchids that can survive harsh winters with their roots and rhizomes safely buried under ground.
Rainfall and temperature are the most common environmental factors used to define biomes.
These environmental factors are largely controlled by where on the planet the biome is located. Tropical biomes are found right along the equator, while subtropical biomes are a bit further away from the equator.
For a more information, check out the charts below!
Because most scientific articles and texts are published using metric units, I spruced up this graph to include imperial units (inches and Fahrenheit) so my fellow Americans could follow along. (Figure adapted from Whittaker, R.H. Communities and Ecosystems. New York: Macimmilian, 1975; and Rickefs, R.E. The Economy of Nature. New York: W. H. Freeman, 2000.)
This graph, called the Whittaker Biome Model, breaks down common biome types over a range of temperatures and rainfall levels. For instance, from this graph we can estimate that a tropical rainforest receives 80-160 inches of rain per year with an average temperature of ~70-85°F.
This graph also tells us a little bit about the organisms (plants, animals, insects, etc.) that live in those areas. For instance, an epiphytic orchid might grow well in a tropical rainforest or a tropical seasonal forest because the temperatures stay warm all year round and both receive sufficient rainfall. However, a grassland or desert would be too dry for an epiphytic orchid while the taiga and temperate deciduous/coniferous forests would be too cold.
Sometimes there are overlaps between biomes that would make this graph very confusing, so not every biome is represented here. For example, this graph doesn’t identify subtropical rainforests, but we can still talk about them in terms of their rainfall and temperature. Subtropical rainforests are characterized by receiving a lot of precipitation, at least 30 inches. They also tend to be cooler than tropical rainforests, although the temperature rarely goes below freezing. Orchids living in subtropical rainforests will be more tolerant of cooler, drier conditions.
This map of the planet is colored for biomes, rather than countries. If you look carefully you’ll notice that there are lateral bands/zones of particular biomes. From equator to poles, it goes: Tropical rainforest – tropical grassland – desert – temperate forest – taiga – tundra. This makes sense because we know that average annual temperature decreases as we move away from the equator.
Jen Schmidt is a graduate student at Cornell University who, with the help of her mother (Barb) is turning into a crazy plant lady at a young age.