CS is a northern gardener whose heart lives in the tropics, and loves exotic-looking plants that make a garden more Brazil and less Boston.
UPDATE: This article started as a single piece, but the topic is simply too large to handle in one sitting. I'm in the process of splitting this into four sub-articles (links coming as they become available!):
Part 1: To Swap or to Sell? (focuses on the general overview and deciding which path is right for you)
Part 2: What Houseplants To Propagate, and How To Do It (some of the best plants to focus on propagating for maximum benefit and minimal effort) (YOU ARE HERE)
Part 3: Valuing Your Propagated Houseplants (focuses on finding a fair trade expectation or asking price for your propagated plants)
Part 4: Where To Sell Or Swap Your Propagated Houseplants (how and where to find out about swaps and sell your plants in the Era of COVID)
Best Houseplants To Propagate
Quick CYA disclaimer: this is not meant to be an exhaustive propagation guide, but rather a starting point/general framework. Given how much plants vary between and among species, detailed propagation techniques should be investigated once you determine which general group below you'll be focusing on.
Disclaimers aside, there's a bit of a Sweet Spot here. Ideally, cultivation should be as easy as possible, and/or have high enough value to make any hassle worth it.
While that balance will be different for each person, some groups are reliably better than others. Here's a decent basic starter list, and the best/easiest ways to propagate them:
Best Ease-To-Value Ratio
Propagation Difficulty: Easy
Trade or Sale Value: High
Best Propagation Method: Pup division
The Deets: Air plants have enjoyed a massive boom in popularity in the last few years, and the endless applications of a cute little plant that doesn't need soil have put demand into overdrive. That said, they're still specialized enough that the market hasn't caught up. Even the most common air plants maintain a price point that seems almost absurd, given the ease of pretty much every aspect of their ownership.
Propagation is predictably simple. Many species will produce asexual "pups" after blooming, à la Hens & Chicks. Gently pry the pup loose from the parent or cut it off with a sharp knife, and put it next to its parent. You're done.
However, there's a catch, and it's central to why air plants are still such a commodity. Pups are produced slowly, if at all, and only by very happy air plants (i.e. blooming). If your air plants are so happy they bloom, watch closely in the next few months as the pup appears and develops. Pups that are ready to be on their own will start to erode the link between them and their parent. If you're not sure, wait until a gentle prodding can dislodge the pup rather than cutting it free.
My general impression is that air plants are better sold than traded. They ship well in warmer months, their value is extremely high, and the subtle charm of the smaller pups is often overlooked at plant swaps, where large, showy plants have the floor. The Monstera deliciosa that everyone is fawning over likely took a fraction of the time your Tillandsia xerographica pup to grow, but air plants traded visual spectacle for quirky charm a long time ago. Reserve your air plants for an arena where they don't have to fight for the spotlight, and you'll be rewarded with the higher return they deserve.
Propagation Difficulty: Essentially Idiot-Proof
Trade or Sale Value: Low (except unusual/rare strains)
Best Propagation Method: Carelessness; willful neglect; indifference
The Deets: Yes, I'm being a bit glib here. But seriously. This group is where every plant newbie starts for a reason. Short of dandelions, this is the tried-and-true bedrock of low-maintenance plant care. They're in every plant store, they're fine being neglected, punished, spray painted, dyed, and generally forgotten for months on end.
So why propagate them? For the same reason that people cook with salt; they're ubiquitous, familiar, and still appealing, no matter how many times you experience them. I see succulents every time I walk in a grocery store, but I still coo at their pleasingly cute stature, their chubby little leaves, the fascinating shapes and patterns they make.
And just like salt (I'm looking at you, Himalayan Pink Ancient Magnetized Extra Fancy Sea Salt Crystals), succulents now have a dizzying array of variants on the classic theme. Succulents are to a plant swap what chili is to a chili cookoff, so the way to stand out is by investing in an unusual and/or attractive variant that sets itself apart.
If you do that, the propagation process barely deserves to be called that. Essentially any shred of leaf or stem that you prune or accidentally knock off will sprout and develop into its own plant, if left undisturbed on soil (or not. I found a complete Sedum plant growing happily from a leaf that was sitting on a bare windowsill for several months). You can quite literally grow them accidentally, provided you don't drown them as many newbies do.
This, alas, is not a secret. Plan on swapping succulents at bargain values, unless you have something truly breathtaking. If you attempt to sell them, know that you will not be alone, and the only way I've found to sell appreciable quantities is usually to sell propagates of common strains for around a dollar or so. Still, your succulents need a trim occasionally, so if you have available space and a handful of cuttings, their utterly foolproof propagation makes it worth it.
My Pick For Best Carnivorous Plant Reference
The Sexy Exotics
Propagation Difficulty: Easy (if keikis are present)
Trade or Sale Value: High
Best Propagation Method: Keiki propagation; clump division (Oncidium, Dendrobium)
The Deets: The Hype continues. Orchids have the best PR of all time, and a mystique beyond what is warranted (more on growing these low-maintenance house plants here:).
As a result, plant geeks like us habitually salivate at the mere mention of these lovely creatures, and their endless diversity warrants the obsessive devotion of their disciples. Even within a species, the floral patterning of each individual is as unique as a fingerprint, and their slow growth greatly increases the value of mature specimens. This combination means that even a common Phalaenopsis orchid can generate a lot of value and interest, both for trade and sale.
Propagating orchids, long the stuff of legends, is actually pretty simple for some of the more common species and genera. Many Phalaenopsis, Dendrobium, and Epidendrum orchids naturally produce asexual clones called "keikis", from the word for "baby/little ones" in Hawaiian. If your orchid has keikis (See photo above), gently break them away from the parent plant, and repot them in sphagnum moss or orchid bark and treat them like your adult plant. Just remember the Rule of Three: a keiki is ready for life on its own if it has three or more healthy leaves and aerial roots. Libraries have been written on this topic, but honestly I've never found much need to get much more complicated than this.
If you have an orchid that grows in clumps (particularly Oncidium and Dendrobium), dividing the clumps is a necessary part of their care, as a happy orchid will eventually try to escape/swallow their pot. When the day comes, simply repot each cane (Dendrobium) or pseudobulb (Oncidium) with healthy leaves after you divide them, and treat them like an adult plant. They will likely need support initially (a stake or similar), but are otherwise fully-functional adult clones of their parent that can flower almost immediately.
In terms of bang-for-buck, asexually propagated orchids are the top of the heap. However, just like their blooms, don't expect to be able to propagate them this way more than once a year, tops. When you do though, this is a heavy hitter at the plant swap and for sale, so expect a premium in both arenas.
Propagation Difficulty: Easy (depending on species)
Trade or Sale Value: High
Best Propagation Method: Clump division; Seeds (esp. sundews)
The Deets: The Up-and-Comers. If "Orchid cultivation" conjures up images of rubber gloves, eyedroppers, and clinical obsession in expensive greenhouses, "Carnivorous plants" summons an image of a swampy little terrarium of flytraps moldering in the corner of a basement somewhere. To me at least.
The world is just catching on to the idea that carnivorous plants are both simple to to grow and incredibly exotic. At plant swaps, Nepenthes is now whispered with the same reverence as orchids, and a mature Darlingtonia or Sarracenia will turn every head in the room. As in orchids, carnivores command a high price and trade value disproportionate to their difficulty.
For many species, propagation is as simple as cultivation, sometimes simpler. Darlingtonia (Cobra lilies), Sarracenia (Trumpet Pitcher Plants), and Venus flytraps are easily propagated by division; simply separate clumps and repot in early winter once they go dormant. Nepenthes are best grown from cuttings; cut a stalk with an actively-growing bud and at least three healthy leaves, and submerge in water until rootlets appear to plant in sphagnum moss.
Sundews, though, are the Wildest Card in the carnivore deck. Drosera capensis is probably the most common, but there are dozens species, including natives to North America. Depending on the species, sundews can be cultivated one of three ways: seeds, separation or gemmae planting (a lot more detail on cultivating and propagating sundews can be found HERE). Seeds and gemmae are treated more or less the same, sown on the surface of the media (sphagnum moss and perlite mixture) and kept very humid in bright, indirect light. The seeds are like dust, so even the most light-handed attempts usually result in a carpet of moss-like seedlings. These can be separated once they have 5 or so leaves and transplanted into their own pots.
However you do it, any carnivore adds practical functionality to their otherworldly appearance (they eat bugs!). This combined with their rapidly-expanding popularity makes these show stoppers worth every ounce of minimal fuss they require, and will pay off, big time.
The Dark Horses
Propagation Difficulty: Easy
Trade or Sale Value: Moderate (depends on the species)
Best Propagation Method: Cuttings
The Deets: As a group, philodendrons display every possible variation on the general theme of "tropical-looking viney rainforest". They like the basic conditions of a house environment, they're easy to grow, and there's at least one in even the most basic of houseplant selections.
As with succulents, the key strategy here is to focus on unusual cultivars and species. For example, Monstera deliciosa is rapidly taking over as the philodendron of choice, and there's a seemingly insatiable demand for them right now, despite the astonishing simplicity of propagating them.
My advice is to go to a specialist plant store, and invest in the coolest/rarest small philodendron you can afford. Let it grow wild for a year, then propagate every cutting you can. An uncommon philodendron generates a lot of fawning at plant swaps, as well as a disproportionately high sale price.
I say disproportionate because philodendrons are some of the easiest plants to propagate (yes, even Monstera). Generally, all you need to do is take a cutting that has 1-2 leaves and a vine node, stick it in a vase of water or potting soil, and put it in average light. If it's not actively rooting in a couple of weeks, try again with a slightly larger cutting, and if you really want to get fancy, dip the cut end in rooting hormone after you snip it. As a bonus, philodendrons also have a lot to offer home decor by turning the propagation process into a work of art, given that cuttings will all have attractive foliage immediately (I've had great results with the propagation rack above).
Propagation Difficulty: Essentially Idiot-Proof
Trade or Sale Value: Low to moderate
Best Propagation Method: Clump division
The Deets: Grasses get overlooked as ornamental houseplants, with the exception of the ever-present "Spiral Bamboo Thingy". Grasses generally spread to fill any container shape, provide a simple but elegant profile, and increasingly come in a wide array of gorgeous patterns and colors.
Propagation-wise, dividing a large clump into small clumps is the easiest method, and hard to screw up. Simply cut or pull apart the clump into the size you want, plant it in standard potting soil, and you're done. If a clump has a core of intact fibrous roots and a few healthy leaf blades, they're almost always fine, and will rapidly expand back out into any new space you give them.
Value-wise, bringing healthy grasses to a plant swap is like bringing Pedialyte to a party: nobody will think to do it, but it'll end up being a hot commodity be the end of the night. That said, only truly unusual grasses will command a high sale price, so this group is ideal as a secret weapon for 'trading up' for an exciting new plant.