Of all the tender perennials, polka dot plant, Hypoestes phyllostachya, is one of the lesser likely to survive winter outside, even if sheltered from the cold. Yet, it is actually becoming more popular as a warm season folliage plant for pots of small mixed perennials. It is a delightful small houseplant, either alone or as an understory plant to larger houseplants like ficus. As an understory plant, It is easier to work with if grown separately in small pots that can get nestled into moss on top of the soil of the larger plants. If it has a problem, it can easily be replaced or removed.
The foliage typically has so many pink spots that less than half of the foliar surface area is green. Some have white or darker reddish pink spots. The bloom is not as interesting as the foliage, and is not often seen. Roots like rich and evenly moist potting soil. The biggest plants are not much more than a foot high. Most stay less than half as tall. New plants are easy to propagate from cuttings. When things get warmer in spring, plants that have more stems than foliage can be cut back to regenerate.
‘Tis the season for seasonal potted plants. These are not well established houseplant or potted plants that live out on porches and patios through the year. Seasonal potted plants are those that are purchased at their prime, allowed to live in our homes and offices while they continue to bloom or maintain their foliage, and then most likely get discarded when no longer visually appealing.
Poinsettia epitomizes winter seasonal potted plants. Florists’ cyclamen, azalea, holly, amaryllis, Christmas cactus and small living Christmas trees are other overly popular choices. All are grown in very synthetic environments designed to force optimal performance, with no regard to survival afterward. They are like cut flowers that are not yet dead. They are true aberrations of horticulture.
Technically, any of them can survive as potted plants, or out in the garden after they serve their purpose as appealing seasonal potted plants. Their main difficulty is that it is not so easy for them to recover from their prior cultivation, and adapt to more realistic environmental conditions. For now, it is best to enjoy them at their best, and try to maintain them at their best for as long as possible.
Eventually, they all experience a phase in which their original growth deteriorates to some extent, while they start to generate new growth that is adapted to the situation that they are in at the time. Christmas cactus are probably the most proficient at adapting, and becoming delightful houseplants. They are even likely to bloom occasionally, although not on any particular schedule for winter.
Holly, azalea and cyclamen can eventually get planted out in the garden. Most hollies grow into large evergreen shrubbery, but do not produce as many berries as they originally did. Azaleas are cultivars that were developed to be seasonal potted plants, so are a bit more finicky than those developed more for landscapes. Cyclamen can be added to pots of mixed annuals and perennials.
Living Christmas trees are not so easy to accommodate. Most are pines that need their space.
It is unfortunate that, like Easter lilies and poinsettias, most kalanches, Kalanchoe blossfeldiana, are enjoyed while actively blooming, and then discarded as their blooms fade. It is so easy to simply snip out the deteriorating flowers, and grow the small perennials plants for their appealing succulent foliage until they bloom again. They do not get much more than half a foot tall, so can stay in small pots indefinitely. They seem to prefer the porosity of clay pots. Because they can rot, they should be watered when the surface of the soil seems to be getting dry, and their drainage saucers should not be allowed to hold water too long. Kalanchoes like bright but indirect sunlight. They can be acclimated to direct sun exposure, but might seem to be somewhat stunted. If brought in before frost, they can be happy out on a patio. The clustered small flowers can be white, pink, red or bright or pastel shades of orange or yellow.
Just like potted chyrsanthemums, azaleas, hydrangeas and poinsettias, potted specimens of Guzmania magnifica are popularly purchased while beginning to bloom, enjoyed as house plants through a long bloom cycle, but then discarded as bloom eventually deteriorates. They are rarely allowed to produce new pups that can be divided and grown into fresh new plants to bloom later.
The bright yellow, orange, red or pink bloom stalks, as well as their rich green basal foliage, are so glossy that they seem to be plastic. The colorful parts of the blooms are pointy strap shaped bracts that arch outward from upright stalks. The leaves below have the same shape, but are longer, and more densely arranged in neat rosettes. Tiny flowers are mostly obscured by the bracts.
Guzmania magnifica, likes bright ambient sunlight without direct sun exposure, and can tolerate significant shade, especially if grown for only a few months while blooming. They seem to like misting, but probably do not not need it. They should be watered only weekly to every two weeks, when the surface of the soil seems to be getting dry. Too much fertilizer might scorch the foliage.
Plants can inhabit nearly every climate on Earth. They live in hot and dry deserts, cold arctic regions, rainforests and just about everywhere in between. Plants seem to have it all figured out. Some even know how to live in our homes as houseplants, although they probably did not plan it that way. Most houseplants are tropical plants that are naturally endemic to tropical ecosystems.
It is actually their tropical heritage that makes them more comfortable in our homes. Tropical climates tend to be conducive to proliferation of all kinds of plants. Those that want to live there must be competitive. Trees compete by growing faster and taller than other trees. Vines compete by climbing the trees. Understory plants that live under taller plants compete by needing less sunlight.
It is these understory plants that do not mind the shade of our homes. Even those that like bright ambient light might never expect to get direct sun exposure. The various ficus trees that might naturally grow tall enough to reach the top of a forest canopy in the wild are still understory plants while young. Because they know how to use resources efficiently, tropical plants do well in pots.
However, these advantages are not so useful out in the garden. Tolerance to partial shade also means that some tropical understory plants need to be sheltered. If too exposed, foliage can get roasted by sunlight or arid wind. (Most tropical climates are more humid than local climates are.) Complaisant roots do not disperse well enough to sustain lush foliage without regular watering.
Ironically, roots of the various ficus trees are very aggressive because they to not disperse deeply, but instead spread out at the surface of the soil where they grow into exposed root buttresses.
The most familiar weakness of tropical plants is their susceptibility to frost. Even though it does not get very cold here, it gets cool enough in winter to offend plants that would never experience cool weather in the wild. Actual frost can severely damage foliage, and can even kill some tropical plants.
Pavement serves a purpose in a landscape. So does decking. They are the flooring of the outdoor spaces that are used for outdoor living. Patios and decks are where we barbecue and dine. Walkways and porches are how we get around the exteriors of our homes. Driveways are where we park cars. For what they get used for, they are better than turf grass, ground cover or bare soil.
So why is it so trendy to clutter pavement and decking with potted plants that would really prefer to be in the ground? It would be more practical to pave less area, and leave more space to plant things in the ground. There would be no damp pots staining concrete or rotting decking. There would be less area to rake or blow, with fewer obstacles in the way. Watering would be much easier.
Well, as it turns out, there are a few plants that should be potted. Houseplants are the most obvious. After all, not many homes have exposed soil where houseplants can be grown on the inside. Even if they did, it is still easier to keep houseplants potted for portability. Plants such as orchids and Christmas cactus, can live in the garden most of the time, and then come in while blooming. Portability is also important for tropical plants that need protection from even mild frost. It might be easier to move them than to cover them.
There are also a few plants that are contained because they are invasive. Mint and horseradish are culinary plants that are so famously invasive that not many of us would bother growing them if they were not so much better fresh from the garden than purchased from elsewhere. Rather than allow them to escape, mint is popularly potted, and horseradish is commonly grown in deep tubs.
Container gardening and growing plants in pots is something that we do for out own convenience, or just because it looks good cluttering otherwise useful parts of the landscape. With only a few exceptions, plants prefer to be in the ground, where they can disperse their roots as extensively as they like. They are healthier, and need less attention. To them, container gardening is unnatural.
The softest and laciest of the asparagus is the asparagus fern, Asparagus setaceus. The extremely small ‘leaves’ (or ‘cladodes’) are less than a quarter of an inch long. The tiny and mostly unnoticed pale white flowers that bloom sporadically in warm weather make it obvious that asparagus fern is not really a fern. (Ferns do not bloom.) If any green berries develop, they are toxic.
The wiry perennial stems can climb like vines to almost reach upstairs eaves, although most get less than half as high. Individual plants produce only a few stems, rarely more than ten. Pruning out old deteriorating stems stimulates new growth. Potted asparagus fern eventually gets crowded with swollen roots, so needs to graduate to larger pots. As a houseplant, it needs regular watering.
It is hard to believe that such a delightfully robust and luxuriant tree like the Indian laurel, Ficus microcarpa nitida, can be so problematic. It looks so perfect, with lustrous evergreen foliage, like something that would be seen on Sesame Street. The broad and dense canopy is very symmetrical and neat. The stout trunk and limbs, outfitted with whitish gray bark, are bold and sculptural.
The problem is that the roots are so extremely aggressive. Buttressed roots elevate curbs, sidewalks and anything else that they can get under. Fibrous roots clog drainage, and strangle roots of more complaisant plants. Indian laurel is a tree that really needs room to grow. The canopy can get wider than fifty feet, and roots will spread much farther if they want to. Fortunately, Indian laurel shorn as a hedge has less foliage, so does not need to disperse roots so extensively.
Staghorn ferns are epiphytes. They cling to tree trunks, rocks or whatever they happen to grab onto. They can root into decayed wood if it is porous enough, but they are satisfied to just cling to the exterior. They do not need soil. They sort of make their own soil by collecting debris that falls from the canopies of trees above. In the jungles where they live, they get all the water they need from rain. They often live in the crotches of branches because that is where they happen to land. (The epiphyte I wrote about earlier was just a palm that landed in the wrong place, but is not really an epiphyte. https://tonytomeo.wordpress.com/2017/11/15/epiphyte/ )
In home gardens, staghorn ferns are often grown on wooden plaques so that they can be moved around like potted plants. Because it does not rain much here, they need to be watered occasionally. They do not grow very fast, but eventually need to be attached to larger plaques, or divided into smaller clumps that fit onto new plaques. Alternatively, they can be grown like plants in hanging pots, but without the pots. Even if they start out in pots, they may eventually envelop and obscure their pots, and form a big rounded hanging mass that only wants water and debris from above. A small bit of fertilizer might improve their naturally light color, but too much will roast leaf margins.
My colleague Brent Green acquired this humongous and well rounded specimen from a client who wanted it removed from an olive tree that it had grown too big for. It had been there for decades. Brent gives it a banana every month or so because it likes potassium. It does not get much debris from above in Brent’s well groomed garden.
They were not always houseplants. They came from somewhere else. Most came from shady tropical forests, which is why they have such big dark green leaves, and are so tolerant of shady home interiors. They are pretty good sports about tolerating the domestic lifestyles that we subject them to, but they would really prefer to be thousands of miles away, growing wild back home.
Home interiors lack the sort of weather that the natural environments of houseplants get. The majority of houseplants would prefer rain, humidity, occasional breezes and perhaps more warmth. Some succulents may not miss the rain, but might crave heat and more sunlight. Regardless of what houseplants want, that can not get all of it in the comfort of our homes. They want to get out!
Unfortunately, that is not an option. Plants that have adapted to the relative darkness and protection from (shortwave or SUV) ultraviolet light in the home would roast if suddenly exposed to direct sunlight. (Windows block SUV light.) They would get battered by wind and damaged or killed by frost in winter. Those that become outdoor plants should be transitioned slowly and methodically.
However, there are a few times a year when the weather is not expected to get too cold, hot or windy, when houseplants can come out to the garden to get very lightly rinsed with a hose. Taking them out immediately prior to a light rain is even better. Rain is gentler and more sustained than a brief and coarse hose rinsing. Both techniques rinse away dust and residue from insect activity.
Rinsing does not eliminate mite, scale or mealybug infestations, but temporarily eliminates the residue from such infestations, and somewhat disrupts their activity. Mites prefer dusty plants to clean ones. While plant are outside, it would be a good time for any necessary repotting, or to apply horticultural oil to control mites or scale. Mineral deposits can also be scrubbed from saucers and the bottoms of pots. If hosed during sunny weather, houseplants should be shaded by a larger tree or awning.