Fall: A Sad Season for Climbing Houseplants

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My pink cissus (Cissus adenopoda, now Cyphostemma adenopoda) attempting a takeover of a white spruce. Source: laidbackgardener.com

September is the time of year for me to bring my houseplants back indoors … and the ones the most reluctant to come in are the climbing plants.

I hang their baskets outside for the summer from the branches of the various trees on my property … and they love it! After long months dangling from their pots with nowhere to go but down, they finally get to do what they really want and reach for the sky. They quickly cling to nearby branches and try to hoist themselves up.

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Propellor plant (Dischidia albida) massively invading my crabapple. Source: laidbackgardener.com

Some have tendrils or stems that wrap around branches, others literally cling to the bark of trees with aerial roots or suckers. They’re doing what comes naturally and it’s easy to see they’re having the time of their lives.

Then comes fall and the return to domestic life indoors. I don’t even bother trying to untangle them from their host: I know from experience that simply breaks stems and leaves, leaving them worse off. Instead, I just cut off the clinging growth and bring them back indoors, shorn and chastened.

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My variegated sweetheart hoya (Hoya kerrii ‘Variegata’) put out a 7-foot (2 m) stem this summer. Indoors, it rarely grows more than 6 inches (15 cm) a year! Source: Laidbackgardener.blog

Which plants do this? Mostly the faster-growing ones, like cissuses (Cissus adenophylla and C. amazonica are two I grow) and mandevillas (Mandevilla cvs), but even the apparently slow-growing hoyas (Hoya kerrii) and dischidias (Dischidia albida) take off at a rapid pace outdoors and need to be chopped back.

The aroids, like the various cultivars of heartleaf philodendron (Philodendron hederaceum) and pothos (Epipremnum spp.), though, always seem slower on the uptake and fail to profit from their summer host trees, just dangling downwards. I still have to trim them back, though, as their stems have gotten overly long and I don’t want plants creeping all over my floor indoors.

It’s a bit like tough love for vining houseplants. I know they hate being pruned, but they’re tropical plants and simply can’t remain outdoors permanently, not in my cold winter climate. So, snip, snip and in they come. Then they can spend the winter dreaming about being back outdoors again next summer!

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A Valentine’s Day Horticultural Rip-Off

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Hoya leaf cuttings sold as plants.

Gardeners are often the victims of horticultural rip-offs, attempts by greedy suppliers to grab their money in return for dud plants, useless products, or ineffective services. Why wouldn’t they try to make a quick buck from Valentine’s Day too?

The Love Leaf

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Anything to make a sale!

You’ve probably seen one and if not, head straight to your local garden center, as they are probably selling them right now: a thick, leathery, green heart sitting all on its lonesome in a small pot. It’s the leaf of Hoya kerrii, sometimes called wax hearts, sweetheart plant, love leaf, or Valentine hoya, and its unique heart shape is certainly surprising. Sometimes the vendor even pushes the envelope so far as to write “I love you” or something similar on the leaf or paint flowers on it. How cute! It sounds like a nice little gift for Valentine’s Day. What’s the problem?

The problem is that, as a gardener, you expect this rooted leaf to grow into plant, right? That, when you bring it home and lovingly care for it, it will one day grow new stems, more leaves and – who knows? – maybe even flowers.

If so, you’ll be severely disappointed. Because the leaf will probably never produce a new stem or other leaves. In the rare case in which it does, that can take years. It usually can’t, because neither the leaf or its petiole has any dormant bud from which new stems can grow. This is called a blind cutting.

Your blind leaf can live for years without growing and without changing: a sort of horticultural living dead (not much of a Valentine’s Day symbol, is it?). After 4 or 5 years, if you continue to take care of it (and its needs are fairly minimal: a sprinkling of water every now and again will suffice and of course, no fertilizer is ever needed), it will simply die one day, having lived out its leafy life.

Very occasionally, a love leaf will, after some 7 to 10 years, put out a stem. That’s because a tiny bit of stem was torn off with the leaf and that did include a small dormant bud. But most hoya leaf cuttings are simply blind.

What Happened?

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This rubber plant leaf is blind: it has produced numerous roots, but no stem. Photo: gardentia.net

Hoyas aren’t the only plants with with leaves that root and never produce a stem. There is a surprising number of plants whose leaves you can coax into rooting, but that will go no further. Several Ficus species, for example, such as the rubber plant (Ficus elastica) and the fiddle-leaf fig (F. lyrata), produce blind leaves. On Facebook forums, I often see thrilled indoor gardeners marveling over the leaf cuttings they took of a rubber plant: “Look,” they crow, “my leaf has roots!” They all look forward to the huge and beautiful rubber plant it will one day become, but they are going to be bitterly disappointed. No plant will ever grow from a rubber plant leaf cutting. A stem cutting, sure, but not a leaf cutting. It too will live on for years, then die for no apparent reason. Such is the way of blind leaves.

Take Your Own Hoya Cuttings

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Stem cuttings of hoya will produce new stems and leaves. Photo:

If you have a hoya at home or a neighbor or friend willing to share a piece, you can easily take cuttings of it… but they will need to be stem cuttings. Insert the lower end of a section of stem with at least two leaves into moist potting soil and, after a few months (hoyas are often very slow to start), the cutting will begin producing new stems and new leaves from dormant buds located on the buried part of the stem, at the leaf axils. You can even take a leaf cutting, at least sort of, as long as you include, along with the leaf, a section of the stem at its base, as that is where the dormant bud will be found. This is called a leaf-bud cutting and it must include a stem section with an axillary bud. Both the stem and leaf will then take root, but only the stem has the ability to produce a new plant, because only it bears buds.

Of course, there are plants you actually can grow from leaf cuttings or even leaf sections: African violets, crassulas, sansevierias, etc. But they all have the ability to produce adventitious buds, that is, buds that appear outside of the usual places. Hoyas, like most plants, don’t have that capacity: they’ll only sprout from axillary buds, buds found on the stem, at leaf axils, not from the leaf or any part of the leaf.

Buying a Sweetheart Plant

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Hoya kerrii ‘Albomarginata’

H. kerrii makes an excellent houseplant… as long as you buy a plant, not a leaf. I have had one for years, in fact, a particularly charming form with variegated leaves called H. kerrii ‘Albomarginata’. Its growth is somewhat uneven (as with many hoyas, it seems sit for months, then suddenly puts on a spurt of growth for no obvious reason) and mine has not yet bloomed… and that’s normal, because it often takes up to 7 years before it starts to flower and my plant is only 4 years old.

Maintenance is a snap because H. kerrii tolerates almost any combination of indoor conditions: sun or shade (although fairly intense lighting is required for bloom), slightly moist to almost dry soil, a humid atmosphere or a dry one, frequent or sporadic fertilizations, etc. What it won’t tolerate is cold: try to keep temperatures above 60˚C (15˚C) at all times. H. kerrii is a climber and can be allowed to work its way up some sort of support, like a trellis. However most people use it in a hanging basket, allowing its stems to extend downwards. Do feel free to shorten the very long stems that occur occasionally.

So, off you go: pick up your own sweetheart plant with its heart-shaped leaves on this day dedicated to romantic love… but do buy a plant, not a leaf!

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Clone a Plant Today through Leaf Cuttings!

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It may seem strange to think that a whole plant can grow from a single leaf. This seems the stuff of science fiction, the equivalent of growing an entire human being from a severed pinky finger! Still, it’s possible… at least for a limited number of plants. Some succulents (Echeveria, Crassula, Sedum, etc.) will even produce  a plantlet from a leaf that simply falls on your window ledge! In general, however, the cutting needs to be in contact with some sort of growing medium to sprout successfully.

Let’s use the African violet (Saintpaulia) as an example of how to produce a plant from a leaf cutting:

422_1-2.KTake a healthy leaf and cut the base of the petiole (leaf stem) neatly at about a 45˚ to 90˚ angle. Insert the petiole into a pot of moist substrate (potting mix, perlite, vermiculite, etc.) about 3/4 to 1 inch (2 to 3 cm) deep, setting it at an angle so that the blade of the leaf is directed upwardly where it can better capture the sunlight it needs for growth. No rooting hormone is necessary, but it is helpful to cover the cutting with a “mini-greenhouse” (a clear plastic dome or bag) to maintain high humidity. Place the cutting in a warm spot, over 65˚F/18˚C at night, with good light but out of direct sun. After a few weeks to a few months, small leaves will appear at the base of the original leaf: these are the beginnings of new African violet plants.

422_3-4.KWhen the plantlets are about 1/3 the height of the mother leaf, separate them (there is almost always more than one baby and sometimes up to 5 or 6!), planting each in its own little pot. Afterward, move them into larger pots as they grow. It is quite likely they’ll be in bloom within 6 or 7 months.

The same method will work on gloxinias, butterworts, begonias (especially rhizomatous begonias) and snake plants.

20150226CWith some succulents (Echeveria, Crassula, Sedum, Cotyledon, Kalanchoe, Aeonium, etc.) it’s even easier. Just drop a intact leaf on a pot of barely moist substrate and, without even any further watering, small roots and a baby plant will form at the end. As the baby grows, begin watering and within a few months you’ll have a nice new plant.

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Leaf section cuttings of Begonia rex. Photo: thegardenilivein.wordpress.com

You can even make cuttings of sections of leaves of some plants (African violets, gloxinias, streptocarpus, several begonias and others). Just cut the leaf into wedge-shaped sections, each with a bit of a main leaf vein, and insert the wedges into a growing medium. It’s best to grow them in a mini-greenouse. After a few weeks or a few months, a baby plant will appear at the base of the mother leaf.

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Sansevieria leaf section cuttings. Note that the plant lets produced will be entirely green, not variegated. Photo: forums.gardenweb.com

In the case of the snake plant (Sansevieria), leaf section cuttings are also possible, but the technique is slightly different. Cut the long leaf into sections 2 to 6 inches long (5 to 15 cm) and press the lower part of each section into a slightly moist substrate. (Warning: if you accidentally plant the cuttings upside down, they won’t root!) Over time, a small plant will grow from each cutting. This technique works well for streptocarpus too. A mini-greenhouse is not necessary or even desirable for a sansevieria, but is very helpful for streptocarpus.

Note that, curiously, if you take leaf cuttings from certain variegated plants, such as Sansevieria trifasciata ‘Laurentii’ (photo above), S. trifasciata ‘Bantel’s Sensation’ or Episcia ‘Cleopatra’, the plants produced will be entirely green, with no variegation. That’s because the mother plants are chimeras, plants that combine two  different kinds of tissues in the same plant, but only the green tissue (the part with chlorophyll) has the ability to produce a plantlet.

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So-called “Valentine Hearts” are rooted leaves of Hoya kerrii. They can live for years, but, unless at least a tiny portion of stem was included with the cutting, it will never produce a plantlet.

One final oddity: there are many plants whose leafs will root and even live for months if not years as independent plants, yet that will never produce any sign of a baby plant, like a stem or new leaves. This is commonly seen in hoyas, begonias, and many other plants.

House Plants to Propagate from Leaf Cuttings

African violet (Saintpaulia spp.)
Begonia (certain species) (Begonia spp.)
Butterwort (Pinguicula spp.)
Cotyledon (Cotyledon spp.)
Echeveria (Echeveria spp.)
Episcia (Episcia spp.)
Gloxinia (Sinningia speciosa)
Jade plant (Crassula spp.)
Kalanchoe (Kalanchoe spp.)
Mother spleewort (Asplenium bulbiferum)
Peperomia (Peperomia spp.)
Piggyback plant (Tolmiea menziesii)
Rex begonia (Begonia rex)
Snake plant (Sansevieria trifasciata)
Streptocarpus (Streptocarpus spp.)
Umbrella plant (Cyperus alternifolius)
ZZ plant (Zamioculcas zamiifolia)