Ultimate Guide to Growing Indoor Plants in Pon [Lechuza Pon]
The first time I heard about Pon was from Kaylee Ellen (from The Rare Plant Shop in the UK and YouTube fame). Leca and Pon are the so-called 'secret' to how a lot of collectors with a huge indoor jungle can manage to care for hundreds (or in Kaylee Ellen's case, thousands), of indoor plants without quitting their day jobs just to keep up with watering - and without over-watering and losing everyone to root rot. Easy peasy.
So of course with my own indoor plant numbers growing (pun totally intended), I had to find out what all the fuss was about. The first time I tried Pon was for propagation. I had some stubborn, hard-to-root Hoya that weren't rooting. Changed to Pon and they took off. Since then I've had great results in my Aroids in general, and especially my Alocasia (including finally escaping the 'one leaf club' where I lose a leaf every time a new one was on the way). Let's find out what this 'secret substrate' is all about, the pros and cons, and what to consider before you try it for your indoor jungle...
What is Pon?
The best-known brand of Pon is Lechuza and in NZ we can now get Bio Pon from Bio Leaf, but Pon is what's in the bag, which gets its name from 'Semi Hydro-PON-ics'. It's a popular 'remedy' for fungus gnats, just like Leca, but tends to be more user friendly than Leca and is used both added to potting mix, as well as by itself.
Pon is a soil-alternative. It looks like small stones or gravel. Normally a combo of pumice, lava rock and zeolites but there are small variations between brands and some also add fertiliser (which you need to be aware of if yours does). Lechuza Pon uses pumice, zeolites, lava rock and slow-release fertiliser. NZ made Bio Pon uses the same (pumice, zeolites and what we call scoria, also called lava rock), but is fertiliser-free.
Depending on the exact mix, Pon maintain a ratio of around 45% water and 55% air. I can almost hear my aroids and hoya breathing a sigh of relief at that, what with their love of chunky, free-draining substrate (and my fear of over-watering). And yes, aroids and hoya are the most popular Pon plants, but Pon is also popular for Bonsai cacti, succulents and many more. When used for moisture-loving plants however, like Peac Lilies, you'll likely be best combining Pon with potting mix. More about that coming up.
What are zeolites?
Zeolites are natural volcanic minerals. These clever little crystal-like stones trap harmful heavy metals and pollutants like lead and nickel. They have high water storage, soaking up excess water to keep the mix airy, releasing water when the roots need it. Zeolites also have a natural fungal inhibiting effect and help balance the pH.
What are lava rocks?
These I had heard of, and they are pretty much what they sound like. Lava rocks are scoria, a type of volcanic rock. Super porous, so full of tiny holes which absorb excess water and nutrients, helping avoid root rot from overwatering and holding on to nutrients until roots need them. Often used as a bottom layer in terrariums and pots without drainage. Scoria or lava rocks are a common addition to bonsai, succulent and cacti mixes.
Do you still need to fertilise when using Pon?
Great question and a very important one when you enter the world of Pon. This also relates to the earlier mention about the fertiliser in Lechuza-Pon. Some Lechuza substitutes don't include fertiliser (which is good), but because Lechuza-Pon does include a slow-release fertiliser, although you do not have to fertilise right away, you DO still need to fertilise long-term.
In some parts of the world you can now get a fertiliser-free version of Lechuza and in NZ we can also now get Bio Pon, a fertiliser-free combination of the same ingredients as Lechuza Pon.
I personally prefer to stay in control of what I feed my plants, when, and how much, to do what I can to avoid fertiliser burn or defliciencies. If using Lechuza Pon, skip fertiliser for one season (about 3 months), after upgrading to Pon, then start with the 'weakly weeky' method after that (diluting your fertiliser and using 'little and often' every time you water).
If you've transferred to Pon in winter, or at a cooler time of year, the slow-release fertiliser will break down more slowly, so you are better to skip the fertiliser for at least 2 seasons (about 6 months) instead before returning to your usual fertiliser routine. But, if you can find yourself a fertiliser-free version of Pon, like Bio Pon, fertilise as normal.
Do you need to change fertiliser when using Pon?
Ideally, yes you do. As Pon is soil-free, if using it by itself, you ideally want to shift your Pon plants onto a hydroponics fertiliser such as GT (Growth Technology) Most soil fertilisers are NPK only, sometimes with a handle of other minerals, but rarely everything a plant needs, as fresh, organic soil will also provide added minerals.
However, in Pon, it's all on you to provide all the minerals your plants need. Look for a fertiliser with all 12 essential minerals. Personally I also like to avoid high-salt ingredients since it's the salts in fertiliser than can cause fertiliser burn. So I also like my fertiliser free of sodium, chlorides and urea. Depending on how sensitive your plant is, you might also like to find one without nickel or cobalt, phytotoxic to sensitive plants even in small amounts.
Can you mix Pon in with potting mix?
Yes, Pon's a very popular additive to potting mixes for plants that like things airy and free-draining. There are 3 mains ways hobbyists use Pon. The 25%, 50% or 100% method.
The 25% method is when people use Pon for drainage only, usually in vessels without drainage holes like terrariums, adding a layer of Pon to the bottom quarter or so of the pot, and the rest on top being your usual potting mix.
The 50% method is a protective Pon layer, with the bottom quarter or so inside the pot, filling in the outside edges, and finishing with a top layer of Pon on the surface to help avoid pests such as fungus gnats, keeping your usual potting mix covered, in the middle around the roots. This method is popular if you're using Pon for it's pest resistant properties (keep in mind that doesn't include all pests, and Pon isn't an insecticide, but more about pests coming up).
The third method is a complete repot into 100% Pon. That involves removing all organic matter like soil and potting mix, rinsing the roots, then planting fully in Pon. This is also popular for avoiding pests (mainly fungus gnats, but more about pests coming up). 100% Pon also helps avoid irritants for sensitive or allergy sufferers such as fungus spores.
The other way Pon can be used is just mixed evenly in to soil or potting mix to make it heavier, airier and more free draining.
Where can you buy Pon?
Lechuza Pon is available on Amazon and for those in New Zealand, (when I can get it), I also sell Lechuza Pon in NZ locally. For those in NZ, you might have more luck getting Bio Pon which is NZ made.
What are the differences between Pon and Leca?
SIZE
Pon tends to be much smaller, like small gravel (it reminds me of the specialist fish tank gravel for aquatic plants), and more irregular in shape. Although Leca can vary in size, even smaller grade Leca it tends to be a lot larger than Pon (that's a scoop of Leca below) and shaped like a ball.
Some find the smaller size of Pon more root friendly for smaller or finer root systems, for less established root systems in younger or root-damaged plants, and for propagating. On a side note, when dropped, I love that Pon doesn't roll away, somewhere never to be found again, which Leca loves to do to me (seriously? every time).
PRICE
Although price varies, the good stuff like Lechuza tends to cost more than Leca. For my budget, that means I save Pon for my plants more sensitive to over-watering, for propagation and for my babies, especially for my Hoya. Leca tends to be cheaper.
TRANSFER PROCESS
If there's one big downside of Leca it's the transfer process. You really must get every scrap of soil off the roots when you change to Leca to avoid root rot. Root melt is common (and expected) with Leca as soil roots die off and your plant adapts and produces water roots, which can be touch and go for less hardy plants.
Lechuza say you don't have to worry about soil remaining on roots when you transition plants to Pon, however I'd still recommend doing the best job you can to remove excess soil if you're going for the 100% Pon method. If going for the 25% or 50% methods (more about all 3 was covered further up), there's no need to remove soil or potting mix (or fern fibre, spagmoss or your substrate of choice), from around the roots.
WEIGHT
Pon is much heavier than Leca or potting mix, as Pon is basically little stones. I love this for both my tiny fiddly pots when propagating, and well as the top-heavy big boys, to prevent tip-over. How light Leca is can be a pain with bigger plants in particular. Of course the weight of Pon tends not to be the best solution for hanging pot situations though, where you want minimal weight.
PESTS
In this area Pon and Leca are similar. Both eliminate some pests, and make others easier to manage. But neither are guarantees you'll suddenly be pest-free. Being soil-less, and super airy, both reduce the likelihood of soil-loving baddies like Fungus Gnats in particular, as well Mealybugs and Root Mealy along with moisture-loving pathogens like fungus.
Spider Mites don't seem to care either way what the substrate is as their entire lifecycle can be completed on foliage. Thrips don't seem to care much either. Whatever pest you have though, treatment is easier for plants in Pon or Leca vs plants in organic mixes like soil or potting mix, as repeated drenches and showering don't have the same high risk of over-watering and root rot as plants in soil or potting mix.
FERTILISER
Leca has zero nutrients. Depending on the brand, Pon often comes with nutrients included (although typically only for the short-term). Both products are best used with a fertiliser made for hydroponics like GT.
Lechuza claims their Pon absorbs excess fertiliser, reducing the risk of fertiliser burn, keeping nutrients in reserve for plants when needed. Whether it does that better than Leca I'm not sure if that's been compared, but both offer that benefit to some extent. I haven't had this happen to me, but if you have baby plants in Pon that are also light feeders, the included fertiliser might be more than they need.
WATERING
Depending on how you water now, you may need to change your watering method for Pon vs how you water with soil or typical potting mix (more about how to water when growing in Pon coming up), but Pon does regulate water better than Leca and stays moist longer and more evenly, making Pon more forgiving of neglectful watering compared to Leca. Using a water reservoir works with both Pon and Leca, but the 'shower watering' method is better suited to Pon. More about that coming up too.
PREP
Leca tends to require a lot of prep (here's how I do it). From my experience, Pon requires far less if not no prep at all. In fact you'll often see it recommended to pot up in non-rinsed, dry Pon (that's because Pon holds water differently than Leca).
pH
The zeolites included in most Pon mixes (including Lechuza Pon), helps maintain a healthy, slightly acidic pH without the need for adjustment, compared to Leca where manual pH adjustment is often needed.
How to water plants in Pon
The watering method you choose largely depends on the pot type. In a self-watering pot you can simply keep the water reservoir topped up once the plant's established. However the shower method is the best option for Pon in a normal nursery pot with drainage holes.
Like it sounds, the shower method just means a thorough top-water, really flushing the pon and roots thoroughly with water, letting excess freely drain out. This method needs a pot with drainage holes. This method is also used with Leca, especially at first to help a plant adjust to it. You want the Pon to be evenly moist throughout after watering (Pon slightly changes colour as it dries out).
Pon has excellent capillary action and stays more evenly moist throughout, so can also be used for wick watering, bottom watering, or with a water reservoir in a vessel without drainage. Feel free to experiment.
Top watering or the 'shower method' (which does not literally require a shower), is what works best for me but I'm planning to shift a few of my established plants to self-watering this season to save on maintenance time since they're a pain to shift to the sink.
You'll find you water less often with Pon vs most other substrates (depending on the substrate's water-holding capacity of course). Personally I heavily top water all my plants anyway, no matter what substrate they are in, so if you're like me, Pon won't require any change to how you normally water.
Important tip for self-watering and wick-watering with Pon
Pon is a favourite for using with self-watering or wick watering for the ultimate low-maintenance plant care. You'll typically only need to top-up the reservoir about once a month depending on the plant, time of year, and size of the water reservoir.
Keep in mind Pon distributes water better and more evenly than Leca, so an important tip is to leave the water reservoir dry for a while before topping it back up each time. This is called a 'dry phase' which - depending on the plant - can be a wait of 2 to 10 days before topping the reservoir back up. On average you'll water even less with Pon than Leca, and certainly much less often with Pon vs soil or potting mix.
How to transfer a plant to Pon
STEP #1 - PON PREP
The shift to Pon does have a few unique requirements. Unlike Leca, if you have a good source of Pon like Lechuza, you do not need to pre-rinse Pon before potting up, saving a huge amount of time. You can pre-rinse if you like, but it's not necessary. The first water after planting is normally plenty to flush out any dust or fines, however Pon is very low in fines compared to Leca. It's often recommended to plant in to dry Pon.
STEP #2 - PLANT PREP
If you're changing to 100% Pon, rinse your plant's roots thoroughly to remove as much organic matter as you can so you have nice clean roots ready to pot into Pon. It seems to be less important to have them 100% free of organic matter vs prepping plants for 100% Leca.
If you're just using Pon at the 25% (drainage layer only) or 50% method (drainage layer, side wall and top), you don't need to rinse the roots as the remaining 50% to 75% of your pot will be filled with your choice of substrate like potting mix.
STEP #3 - POT UP
Add a layer of Pon to the bottom quarter or so of the pot. Rest the root ball on that layer then fill the remainder with Pon, or if adding Myco for the roots, sprinkle a little Myco on the bottom Pon layer, directly under where the root ball will go, before adding the plant and the filling with Pon. Being smaller and heavier than Leca, Pon secures and holds plants in place better.
STEP #4 - WATER
After potting up, top-water thoroughly until the Pon is evenly wet and water really pours out the drainage holes. The same as soil or potting mix, you'll normally see the 'fines' wash out in the first water (cloudy brownish white particles), but nothing like the excessive fines you'd expect from Leca.
If using a self-watering pot or pot without drainage, tip out any excess water in the bottom. You don't have to fertilise, most Pon already includes short-term slow-release fertiliser, but can add a little seaweed to the water if you like to help the roots transition and recover.
The secret to this last step however is NOT to water again for at least 2 weeks if using the shower watering method (heavy top watering). If in a self-watering pot or wick watering with a reservoir, make sure to leave the water reservoir empty for the first 2 weeks.
Pon holds water better than Leca, so after the initial drench when repotting, step away from the watering jug! If your plant is really going through the wars and desperate for water before 2 weeks is up (normally for a plant that must be kept moist and can't handle drying out), you may need to water before 2 weeks is up.
For the majority of our aroids and hoya though, whether in a self-watering pot or not, give watering a rest for at least a fortnight after potting into Pon, adnd keep that water reservoir empty. At around the 2 week mark, the Pon will normally have changed colour as it's dried out. You can feel moisture with Pon so can also check with your fingers.
Go ahead and fill up the water reservoir a little now and check the water level is slowly going down over the next few days. If you see signs the water is being used, now you can go ahead and fill your water reservoir to the max and off you go as normal.
Does Myco work with Pon?
Yes! Myco will live and grow in Pon. The perfect time to introduce myco is when transferring a plant to Pon as the best place to add it is just below the root ball (it needs to be in contact with roots and below the surface, not exposed to sunlight). In hydro or semi-hydro, myco extends the root system and helps protect roots from pests and diseases (the brand I use is Seacliff Myco).
How long does Pon last?
This is a key difference to most other substrates. Pon is reusable, over and over again. Although it tends to be more costly up-front, it doesn't break down like most other substrates, and can last years. Not only will you need to repot less often, you can also keep any leftovers ready to reuse instead of buying more potting mix all the time.
Do you need special fertiliser for Pon?
In a way, yes. Although it does depend on your watering method. If you top water (the 'shower method'), then it's less important as top watering helps wash away excess fertiliser salts. If you combine your fertiliser with seaweed the seaweed will help 'fill in the blanks' for what your fertiliser doesn't provide (as most fertilisers are not complete). Plant Runner is one that does this for you, combining an NPK fertiliser with organic seaweed all-in-one. However what most people do - same as with Leca - is shift to a fertiliser formulated for hydro and semi-hydro.
Fertilisers for hydro and semi-hydro will normally be complete and balanced, including all 12 essential minerals, not just the 3 macro's (nitrogen, potassium and phosphorus), like many soil fertilisers do. I prefer hydro / semi-hydro fertiliser for all my plants, not just those in Leca and Pon.
One of the best here in NZ is GT (Growth Technology). GT is free of urea, sodium and chlorides to reduce the risk of fertiliser burn, and free of phytotoxins cobalt and nickel, for sensitive plants. Being free of chlorides if a biggie (the most common, highest-salt ingredient in most fertilisers). GT is also pH balanced.
There you have it. The pros and cons, ins and outs, tips and tricks to growing plants and propagating in Pon or Lechuza Pon. If you have any other Pon questions I haven't answered here, please do get in touch. Always happy to help. Anna :)