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Carnivorous Plants: Can Hydroponics Support These Curious Plants? · Hydroponics Daily

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Hello, and welcome back to Hydroponics Daily, the podcast where we explore soilless
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growing systems, specialised crops, and the science behind modern horticulture.
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I'm your host, Dr. Russell Sharp, and today's episode, we are delving into the
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unique and captivating topic of cultivating carnivorous plants.
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Not one for vegan plants or vegetarian plants this time.
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So, carnivorous plants, they're botanical curiosities that fascinated scientists
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and gardeners for centuries, not only for their exotic appearance,
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but also for their remarkable adaptations.
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Today we'll examine how they work, how to grow them, and whether hydroponics
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can support these extraordinary plants.
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So are these a plant that can be used in hydroponics?
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So carnivorous plants are species that have evolved to derive their nutrients
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or some of their nutrients, particularly nitrogen, from trapping and digesting
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insects and other small organisms.
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Why do they do this? Well, they typically inhabit nutrient-poor environments,
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especially bogs, but also sandy wetlands as well.
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So they're the two environments where you're going to find them,
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acidic bogs and sandy wetlands.
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And so if you're going to grow them hydroponically, you're probably going to
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need to mimic those conditions.
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So traditional root-based nutrient uptake is inefficient.
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Famous examples of carnivorous plants? Well, the most famous one is the venous
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flytrap, Dionea muscipula.
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That's a difficult scientific name, is that?
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Then we've got the picture plants, which are probably the second most famous.
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And then you've got the nepothees, which I think are from Asia,
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and the sarancenia, which I think are from America.
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And you'll find that the asian pitcher plants they their pitchers are on the
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end of the leaves and that's how they've evolved it's sort of like a modified
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leaf whereas the american pitcher plants they are from the rosetta flowers they're
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not from the end of the leaves and they're actually unrelated and it's a,
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biological evolutionary mechanism called convergent evolution where they've evolved.
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Separately in similar environments to have the same
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feature even though they're completely unrelated
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so that is clearly the best option in
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that situation is to have a picture and develop it and
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it's not like they can look at the alternative plant and say oh yeah
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that's a good idea i'll copy that they're a completely other side of
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the world they're they're non-thinking plants and so
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that's why an amazing thing about evolution is that they've evolved
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the same mechanism and we know that they're in completely different
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ways because their genetics is different and the way they actually
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grow one from the leaf and one from the rosette is completely
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different so that's picture plants that's one example of
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convergent evolution or similar to parallel
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evolution another one is cactuses and
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euphorbias and a lot of euphorbias look
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like cactuses and you might think oh they're the same
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but actually if you study them you'll find
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that there's different ways they look different and they their
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biology is very different euphorbias are from africa and
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obviously cacti are from the americas back to carnivorous plants the second
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most famous third most famous are the sun jews these are ones that have got
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little sort of trichome spikes gluey spikes that trap the any insect that lands
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on them and then the leaf folds over and then the butterworts or pinguiculas.
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And these have just got sticky leaves. And then we sort of have hemicarnivorous
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plants or semicarnivorous plants where insects sort of get stuck to them and
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they don't produce enzymes.
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But, you know, scientists believe they might derive some nitrogen from just
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the fact that because they're sticky and plants get attached to them.
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I think things like teasel are classed as semi-carnivorous.
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So despite their dramatic mechanisms like snapping traps in the Venus flytrap,
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sticky tentacles and pictures, carnivorous plants still rely on photosynthesis
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for their energy and they require moisture through their roots.
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So they're not parasitic, they're not getting all their nutrients,
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it's not like a lion or a tiger that's carnivorous, they're
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still getting their actual energy from photosynthesis
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they're just getting nitrogen mainly from from
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the animal that they trap well what
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environmental conditions do they require if you're going to grow them well obviously
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they're going to need water and they require pure mineral free water not tap
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water if you're going to use make sure you've got a good dechlorinator like
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dr hydro dechlorinator ideally rainwater distilled reverse osmosis or.
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One that's um has its minerals removed light most species thrive in bright indirect sunlight.
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Under full spectrum grow lights with a high uva light
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output nothing particularly out of
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the ordinary there i mean bogs and wetlands they're
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going to be fairly high light levels these are not shade loving
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plants mostly you don't find many on the forest floor
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humidity many species like nepenthes
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pitchers and drossera prefer high humidity
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often above 60 degrees and the
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soil while not soilless by nature they
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grow in inert acidic media such as sphagnum moss
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perlite or silica sand and nutrient-rich
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soils would be harmful to them so don't grow them in in anything
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with a really high ec fertilizer right
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so then that's one of
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the reasons why i think the rhs or
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q gardens they they tried to ban peat-based growing
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media but they still use peat especially at
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q that certainly used to be the case they use peat especially for acidic
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loving carnivorous plants because that's their natural environment and
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they just couldn't grow them without them so the real
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question can carnivorous plants be grown hydroponically well the
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short answer is partially while true hydroponic cultivation so a water-based
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system with dissolved nutrients sort of dwc nft is generally not recommended
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but semi-hydroponic inert media setups can work well so passive wick or tray
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system many growers use a simple tray filled with ro water.
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Passive systems like autopot would work work well with this you the inert media
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sort of like Sphagnum moss rather than cocoa, perlite,
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these substances hold water without releasing nutrients, making them ideal for carnivorous plants.
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Some things like the pitchers from Asia, they can grow well in lecker,
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that sort of volcanic or expanded clay aggregate.
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And just make sure the nutrient levels are kept really, really low.
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Don't use a really high nutrient level. Certainly don't use anything really high in nitrogen.
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So don't use your standard hydroponic nutrients. They're extremely sensitive
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to high EC values as well as just high nitrogen levels.
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You can give them foliar treatments. However, you're probably best just to feed
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them insects, dry bloodworms are obviously a great example and just foliar sprays
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at very, very diluted levels.
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We said that the Venus flytrap is a very common species.
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It does require a dormant period in the winter and bright light during the summer.
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I've tried to buy some Venus flytraps here in the UK and
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they're only available for sale for a few months of the year because
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they can't guarantee they'll survive if they ship them
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out anytime cape sundews are another very common
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one they look very pretty look great on photographs very
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adaptable excellent for beginners and then the
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best picture plant for beginners and indoor
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grows is nepenthes alata and and
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then for the american one saracenia purpura so
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they're available from specialist nurseries and they'll
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come with specialist care instructions so just make
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sure you follow them to the letter so tips for
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success always use mineral-free water strong lighting
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give the temperature and humidity consistent don't use
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the trigger traps on the Venus fly trap or the sun juice unnecessarily without
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a feed feeding insect because that'll deplete the plant's energy and observe
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the dormancy requirements especially for temperate species there are a number
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of temperate pitcher plants and obviously carnivorous plants okay some other top Facts.
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Carnivorous plants are thought to be mostly if not all non-mycorrhizal so no
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need to add a mycorrhizal product there and that's thought to be because the
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grow media is so acidic that um.
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Fungi will not tolerate those conditions and
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also there's no phosphate to solubilize in
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those sort of boggy conditions so the mycorrhizal are not going to do their main function in
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them anyway so the plants are not going to give 15 of their carbon from photosynthesis
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to the mycorrhizal in exchange for nothing so they've
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evolved to be non-mycorrhizal there is a bromeliad
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from south america called puya chilensis and
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it's purported to snare large animals including sheep
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on its stiff spiky leaves and
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use the decaying carcasses as a fertilizer however however
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actual evidence for this happening in real life is
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very limited so yeah you don't see
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many sheep impaled sheep impaled on
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puya chilensis in the wild i think it's probably just more
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a someone's imagination got away with them there
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is folklore in brazil in the rainforest that there
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is a plant that is able to a man-eating tree and but no species has ever been
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discovered with this sort of triffid like ability however it could just be that
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no it's just so good at ensnaring its victims that nobody has ever returned from viewing it.
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Isn't that a thought? Maybe there is a tree, a human eating tree out there in
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the rainforest, but no one's ever successfully returned. It's that good at trapping its victims.
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Carnivorous plants make up only 0.2% of all plant species.
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So even though they're popular in horticulture, they're actually very rare in the wild.
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Do they hold potential for capturing and killing unwanted
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pest insects could you keep a few carnivorous plants
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in your grow room where you've got other crops to help
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control pest and disease or do
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they actually release chemicals that attract insects to
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their area so they can catch them that's probably to
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be determined that one it's certain that carnivorous plants
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when you look at their flowers they always have their flowers on long spikes
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held a long way into the air and that's to stop pollinators from being trapped
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in their actual traps because obviously a carnivorous plant doesn't want to
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eat its pollinators because its ultimate aim is to reproduce and spread its genetic content.
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Going to that pest control there.
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Sounds a bit fanciful, but Portuguese farmers have had a history of using adhesive
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leaves of Portuguese sun dew to catch flies in and around their crops.
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That species has very long leaves, up to 40 centimetres. So that's massive for a sun dew.
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And they sort of use them, they pull them off the plant and use them sort of natural fly paper.
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And although this sun dew species is an alpine species, it grows in the mountains,
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and it's frost tender, and so it would need to be detected in the winter if
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you grew it in the UK or anywhere else.
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Sort of temperate there is a sundew in australia
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that is reported or reputed to
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catch squirrels mice and even rabbits so that
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in theory could be used in your home or your garden for
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rodent control and then some of the pictures
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in indonesia malaysia and the philippines they produce
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extremely large pictures and they use enzymes
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and acids and specialist bacteria
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to digest the insects so they're not just water in there there's
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actually sort of like a stomach and all the things that you find in a human
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stomach are in there and that some of them can go big enough to digest frogs
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birds shrews and again even rats that are attracted to them which is pretty
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grim isn't it okay so rather than luring rodents to their death.
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It's actually you're probably they're probably
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actually providing a sweet nectar to lick them and
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then the rodents defecate in the pitcher and exchange
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that for nectar it's probably more of a mutualistic thing
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than the rodents are probably just getting a bit stupid and
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falling in rather than the pitch is sort of
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evolving to catch rats they're probably just feeding
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the rats in anything so i wouldn't be putting pitch giant pictures
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in your in your house or your grow room because you're
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probably just going to attract rats rather than actually kill rats and
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venus flytrap it's been found to catch beneficial insects
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as well as pests so again non-selective there
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butterworts which are these sort of ones with the sticky leaves that don't actually
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look like carnivorous plants they're really good at catching fungus gnats so
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they might be they're probably the best ones to grow hydroponically because
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they're going to catch fungus gnats in your young developing seedlings which
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are a massive problem in hydroponics.
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Another interesting fact about pitcher plants, they have specialist cells on
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the lips of the pitchers.
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They almost look like human lips, or yeah, I'm not going to go there.
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And when they're moist, these specialist cells cause the insects that alight
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on them to actually aquaplane off them and into the trap.
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So you know insects are normally really good at attaching to surfaces,
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and a blue bottle fly can happily
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sort of sit on your ceiling or your walls well
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when they land on a pictures picture plant these specialist
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cells they're just aqua plane off as if they're in
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a you know on sort of you know a lubricant
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straight off into the into the picture and away they go we have eight species
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that are native to the uk that are carnivorous plants we've got a lot of bogs
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in the uk because we've got a lot of rain so that was not that surprising and
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you can actually there are some aquatic underwater Water.
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Carnivorous plants as well, such as bladderwort, articularia.
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So I said there were some plants that are considered sort of half parasitic
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or not really parasitic.
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One of them, the technical term for that is proto-carnivorous.
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And one species is the common weed, shepherd's purse.
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And that's got the capacity to attract, catch, and digest bacteria and nematodes
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in the sticky mucus layer surrounding the germinating seeds.
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It's not actually the actual plant, it's the germinating and seeds and so
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it's not strictly speaking carnivorous and shepherd's purse is a
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weed here in the uk but it's actually grown as a crop in china
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and i think in japan as well so yeah proto-carnivorous
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plants they've got a sticky surface which possesses enzymes that
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break down insect proteins and these plants
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digest any material trapped in that
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mesolage sticky substance and it's
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a source of nutrition or it could be a source of defense who
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knows this time of year in the uk we get a lot of campion
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plants or selenium and they possess sticky
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stems and again they another name
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for that plant is catch flies because the stems catch the flies and
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they can absorb and use the proteins from the animals they get caught
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on teasel that's another plant that grows very
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commonly in sort of woodlands around where
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i live here and that's proto-econovirus and
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then back to the rainforest the bromeliads they're these
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plants with like a pool of water on the inside or
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rosettes and they're considered proto-econovirus because the water that collects
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in the base of the leaves it's sort of like a primitive pitfall trap but it's
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not the primary structure of those structures the primary function of those
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structures is to catch water so that they can live in the in the treetops in
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the in the canopy and survive and a
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few insects might fall in, there's no enzymes, there's no acids there to dissolve anything.
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So that's a number of other plants that are considered proto-archinivorous like
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monkey flower and trigger plant.
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Some of the North American bitter plants are actually quite hardy,
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unlike the tropical ones, and they can go down to minus 10 degrees Celsius.
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Don't ask me what that is in Fahrenheit, but that's 10 below freezing.
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And they can actually eat a lot of slugs and snails.
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So that's exciting from an
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English gardener's perspective because slugs and snails are the
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number one pests in an english garden so that's exciting
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20% of their diet can be made up of mollusks and
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there's even a plant in brazil called philcoxia and
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that has an extra set of leaves that grow underground that
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are sticky and these subterranean leaves are thought.
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To trap nematodes and they exude protein
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digesting enzymes proteases that decompose
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nematodes body so philcoxia could
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be a good one if you're growing potatoes because they could trap cyst
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nematodes that love to eat potatoes and
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then another south american species is moth flower
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and that's thought to attract moths so if you're growing apples it
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could potentially trap coddling moth you know
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there's all potential for carnivorous plants beyond just.
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Growing them for ornamentals and for pure curiosity so
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the question then is with all these amazing traps
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do carnivorous plants get attacked by
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pests and yes they do unfortunately you're
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still going to get pests on your carnivorous plants you're still
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going to get insect pests so as many sun jews are
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attacked by moths plume moths caterpillars and
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they first eat the sticky traps in one area and
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then negotiate their way around the leaves to feed on
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the photosynthetic tissues and so
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that's not cool is it so you don't want plume
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moths caterpillars and they possess
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specialist skin cells that are designed to be pulled off should
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the caterpillar should the caterpillar get
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ensnared on the traps so yeah you
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need to look out for caterpillars if you're growing carnivorous sundew plants
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probably fungus gnats as well you're probably going to get loads of
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fungus gnats probably too many that the plants can't
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eat them because you've just got damp acidic decomposing boggy
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grow media propagating carnivorous plants
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is in some ways very similar to normal
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plants you can get seeds and those flowers on that turn
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into fruits on the spikes above them however they a lot also propagate by something
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called vivipari where little plantlets appear on the end of the leaves and you
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can just pull those off and you get new plants so vivipari not many hydroponic crops are viviparous.
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Micropropagation is the way that most of them are produced commercially and,
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because it's a lot easier to produce multiple plants in that way.
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Similar to orchids and bromeliads, it's the number one way of propagating them.
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And as I said, too much fertilizer can be bad for the carnivorous plants.
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It might be just toxic to them, or it can actually turn them vegetarian.
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If they get all the nitrogen they require from the fertilizer,
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they'd stop producing the traps in such great details,
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and things like Venus fly traps or the sun juice can stop
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responding and using energy to try and trap things
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the pitchers might dry up because they just
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don't need the to waste energy getting
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any more nitrogen so you can turn your plants your carnivorous
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plants vegetarian by feeding them too much that's been what i think is a very
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interesting topic i hope you did too if you thought it was interesting please
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share it with someone who likes carnivorous plants and if you had this episode
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shared then you owe that person who shared it with you a beer so take them down
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the pub or if you're you don't drink alcohol you owe them a,
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fanta lemon okay thank you very much for listening until tomorrow goodbye.