Houseplant clinic: from crispy ferns to collapsed cacti, all your problems solved

My cat/toddler likes nibbling my plant’s leaves. Should I be worried?

Possibly. There are many houseplants that are toxic to some degree, so if your pets or children are likely to get hold of your plants and put them in their mouths, it’s worth making sure you know what you are growing and keep anything harmful out of their way. Many aroids, such as devil’s ivy (Epipremnum aureum) and the Swiss cheese plant (Monstera deliciosa), are toxic to humans and pets, for instance. Consult the ASPCA for a useful database of toxic and non-toxic plants.

Help! My wilted plant doesn’t perk up when I water it

Houseplants can wilt when they have too much water, as well as too little. So by watering again you may be making the problem worse. Take the plant out of the pot and push your finger into the rootball. If the soil is bone dry, put the plant into a bucket of water and let it soak for an hour or two, then drain thoroughly. If it’s soaking wet, knock off the wet compost, trim any mushy roots and repot in fresh, only slightly moist compost. Most houseplants recover better from drought than from flood, so never let them sit in water.

How do I get my orchid to bloom again?

If the flowers have recently died back, try cutting the flower spike back to just above a node (feel for a bumpy, scale-like bit along the stem) with clean scissors, and it may send out fresh buds. If the flower spike is brown, cut it back to the base of the plant and wait. Moth orchids (Phalaenopsis) usually flower once a year, so keep watering and feeding, and wait for a new flower spike to appear. There is some debate about whether a fall in temperature at night of between 3C and 5C helps kickstart flowering; this won’t harm the plant so it’s worth a try if it’s been more than a year since the last flowers; turning your heating down or off will help create the required drop in temperature.

My fern is a crispy mess. Should I throw it away and try again?

Don’t give up yet. Many ferns grow from rhizomes – thick underground stems – and will resprout even if all the foliage dies back. The secret with ferns is to provide a steady supply of moisture around the roots; one way of doing this is by using a self-watering pot. You can also try double potting, where you sink your fern in its plastic or terracotta pot into another, waterproof pot full of damp compost, gravel or sphagnum moss. If your fern really has died, try an asparagus fern next time: a fern lookalike that gives the fine foliage without need for constant coddling.

I am looking for a big, showy plant for my living room that’s easy to care for – any ideas?

A sunny room is perfect for a mature specimen of the ponytail palm (Beaucarnea recurvata): although the topknot of straplike foliage on a woody stem does lend it a palm-like appearance, it’s actually a member of the asparagus family, and is less sensitive to dry air and the occasional drought than a true palm. For a room with no direct sunlight, the dragon trees, such as Dracaena fragrans and D. marginata, are wise investments that will cope with the most erratic care regime. The main thing that will kill both of these plants is waterlogged roots, so only water when the soil is dry.

I kill everything I touch. What plant will survive, even in my hands?

The ZZ plant, Zamioculcas zamiifolia, is the houseplant I usually buy for people who claim they cannot keep plants alive. It’s a stoic but beautiful foliage plant from east Africa that can cope with a huge spectrum of conditions. If you like a touch of the gothic, the almost-black foliage of Z. zamiifolia “Raven” will appeal.

My succulent grew tall then fell over – help!

Too little light and too much heat in winter is to blame. This causes succulents to stretch out (the botanical term is etiolation), and they often get so tall that they droop. Try to find a sunnier spot for your plant: a south-facing windowsill, covered porch or balcony is ideal. If your home is too dark for that, you may need to invest in LED growlights: Sansi sell bulbs that fit into regular light fittings.

Should I worry about the white fuzzy stuff on the soil?

This common issue is caused by saprophytic fungi, which live in soils and feed on decomposing plant material. They won’t directly harm you or your plant, but their presence probably means your potting mix is a little too water-retentive, or you are watering too frequently. Take the plant out of its pot and look at the roots: check for soft or dead roots and cut these away. If the potting mix needs replacing, knock off all the old compost and pot up in fresh houseplant compost, adding some perlite or grit to improve drainage. Gently scrape the top surface of mould away and discard, replacing with fresh compost. Mulching the soil surface with expanded clay pebbles (leca) or gravel may help to stop the return of the fungal growth.

To get the plant back to its original shape, you can chop off a section of stem, allow it to dry out for a couple of days, then place in gritty compost or a glass of water until rooted. The plant left behind should resprout.

What plant can I put in my windowless bathroom?

No plant will survive long term with absolutely zero light. But if you can leave the door open most of the time so light can get in from the neighbouring room, you could try buying two or three identical specimens of shade-tolerant plants such as the peace lily (Spathiphyllum wallisii), the cast iron plant (Aspidistra elatior) or even the ZZ plant mentioned above. Give them a spell in a brighter spot elsewhere every few weeks.

What can I do about the tiny black flies floating around my plants?

Fungus gnats, also known as sciarid flies, are different from the fruit flies that hover around your fruit bowl, which are bigger and brown in colour. Fungus gnats lay their eggs in houseplant compost, and their larvae (transparent, black-headed worms 5-10mm long) feed on fungus and algae in the soil. They don’t do much harm to mature plants but can kill seedlings. Either way, they are unsightly and annoying.

The safest way to tackle the problem is biological control – hypoapsis mites or nematodes that will kill off the larvae. These treatments are safe for humans and pets: applied twice a year, they will keep the problem under control. In addition, try Zoot Off Sciarid fly granules as a top dressing on your pots. This discourages the flies from laying their eggs.

• Jane Perrone is host of houseplant podcast On The Ledge

Pots in the post: 10 of the best houseplant delivery services

Bunches Family-run, specialising in flowers and small, colourful houseplants. Has recently branched out into large indoor plants.

Bloombox Founded by a former therapist, it sells plants with a wellbeing focus, with regular collections, from pet-friendly to immune-boosting plants.

The Little Botanical Stylish plants in gorgeous ceramic pots, as well as accessories.

Canopy Plants Wide range with sustainable packaging (no single-use plastics), and offers subscriptions.

Leaf Envy This London store delivers nationwide: collections include air-purifying plants. Lots of tips on plant care.

Hortology Everything from small succulents to large, office-sized palms – and offers suggestions for plants by room.

Beards and Daisies A trend-led, curated selection, with great in-situ photography for inspiration.

Patch Shop by type (unkillables, shade-lovers) or room; also sells outdoor plants and trees.

Flowerbx This flower specialist also sells a curated range of plants, as well as a wide selection of orchids.

Papaya Born during the first lockdown, this site sells a variety of plants in Insta-friendly pots.