Episode 58: Indoor ferns (or, how not to kill your darlings)

Ferns galore... but how do you keep them alive? Photograph: Jane Perrone

Ferns galore... but how do you keep them alive? Photograph: Jane Perrone

Ferns. Love them, hate them, want them to go away and stop taunting you with their crispy leaves? This week I am attempting to give serial fern killers hope by discussing some tips and tricks to keep ferns happy, interviewing someone who's got their fern game sorted, and naming some of the species I find just that bit easier to keep alive. 

The indoor fern family is enormous - with literally hundreds if not thousands of ferns that will grow indoors with the right care. From the leathery antlers of the staghorn ferns to the delicate papery leaves of the maidenhair fern, there's something for everyone. But they're not the easiest of houseplants, to say the least. I bet there are many of you who can identify with that moment when you discover that your precious little lush green specimen has turned crispier than Donald Trump's hairdo.

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Ferns like to have their compost continuously damp, so there are various ways to ensure that you don't let the rootball dry out. Here's my top tips for fantastic ferns: 

1. Put your fern in a terrarium or place it under a glass cloche - this increases air humidity and cuts down on evaporation of water from the soil. The picture to the left shows Hessayon's fern column setup.

2. Ceramic watering spikes can help keep moisture levels even. These are the ones I have.

3. Potting onto a slightly larger pot can help if your fern is in a tiny container that dries out really quickly. Adding vermiculite is also worth doing if you are repotting, as it helps to hold moisture in the soil. 

4. Making yourself a fernery by gathering your ferns in one place helps in a number of ways: it makes it easier to water your ferns all in one go, and increases air humidity locally.

5. Wick watering, as described by Dale Martens in episode 54, is a great option for ferns, and cheap too. There's a nice visual guide to wick watering using African violets as an example here.

6. Mulching the top of the pot can help to slow down evaporation from the soil surface, and may slow down fungus gnats a little, too (but listen to episode 19 for the full details on how to stop fungus gnats as this is by no means a complete cure). You can use grit, gravel, pebbles, glass beads or slate chips or pretty much anything you fancy - all will work to keep soil damp for longer.

7. Switching from terracotta to plastic pots is wise when growing ferns. Terracotta is porous so will lose water more quicly than a plastic pot - you can always hide the plastic pot behind a nice cache pot. 

8. Double potting is where you sink a pot into another, waterproof pot full of damp compost. it helps to insulate the rootball against temperature changes and keep them cool and damp. 

'Hello, my name is fern!' Raffaelle with his massive fern. Photograph: Rafaelle di Lallo.

'Hello, my name is fern!' Raffaelle with his massive fern. Photograph: Rafaelle di Lallo.

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Raffaelle Di Lallo only has about four ferns, but has become notorious for one gigantic fern - he bought it at a hardware store three years ago as a small plant - the plant label just said something like hello my name is fern. He asked the wisdom of the internet and he thinks he's narrowed it down to Nephrolepis exaltata 'Fluffy Ruffles' or Nephrolepis pendula.

I interview Raffaelle to find out the secret of keeping this huge fern looking fabulous. Key point: misting your ferns is not the answer to increasing humidity and keeping your ferns content. He also reveals how he adds a dilute fertiliser with every weekly watering, and how his finger is the best tool to use as a moisture indicator.

Find Raffaelle online at ohiotropics.com and on Instagram as @ohiotropics.

Question of the week

Jessica emailed in with a concern about her satin pothos, Scindapsus pictus 'Argyraeus', which has some brown blotches on the leaves. She writes: "It seems mostly healthy and content, but ever since I acquired it last year, it's been developing yellow and dark brown splotches on a few leaves at a time. It's producing more new leaves constantly, so I'm not really worried about it, but I would like to figure out what's causing the splotches. It doesn't seem close enough to the window to get sunburned. Do you have any ideas?"

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Well, my rule of thumb with weird stuff turning up on leaves that looks like something other than pest damage is that anything that is happening to 10% or less of the leaves (roughly) isn't too much of a problem. I'd advise removing damaged leaves and keeping an eye on the plant in case more leaves become affected. I'd suspect that the brown tips are due to a bit of dryness around the roots at some point, and possibly a slight drop in humidity. Removing damaged growth will also prevent your pothos from becoming too spindly. The book I refer to in this question is Nature's Palette: The Science of Plant Colour by David Lee

Want to ask me a question? Tweet @janeperrone, leave a message on my Facebook page or email ontheledgepodcast@gmail.com. There's an episode about moth orchids coming soon, so I'd particularly like to hear from anyone with a Phalaenopsis problem to solve.

Easy-care(ish) ferns

If you've killed the rest, now try these tough(er) customers. 

Asparagus ferns (which aren't really ferns, but who's counting?)

These 'ferns' are far more tolerant of the vicissitudes of a dodgy watering regime and will survive in many locations in your home. If you've failed with all of the above, give asparagus ferns a go!

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