One aspect of houseplant care that is often made more complicated than it needs to be is repotting.  If you listen to some experts on Gardeners’ Question Time, or similar programmes, you might be forgiven for thinking that this is a tricky annual chore.  Actually, it is very straightforward and if you follow some of the tricks of the professional interior landscaping trade, you will find that it is something that needs doing very infrequently.

Why do you need to repot houseplants?

As your houseplants grow, there will come a time when they need to be planted into a bigger pot.  Their roots will be crowded and you will find it increasingly difficult to maintain the right moisture conditions, which means unhealthy fluctuations in water, possible root damage and an increased risk of yellow leaves or even leaves falling off.

Repotting a plant into a bigger pot will extend its life and make routine care much easier.  The roots will find space to grow and, because there will be more compost, watering will be easier to manage and moisture fluctuations will be more gradual.  There will be less risk of overwatering and underwatering your plants.

An increased bulk of compost will also protect the plant’s roots against severe fluctuations in temperature.  Even if the air temperature changes (which is not ideal), compost temperature will change much more slowly.  If your plant gets accidentally damaged by chilling or overheating, there is a chance that it will recover if there is enough soil to protect the roots from sudden changes in temperature.

There is also an aesthetic reason to repot your plants.  As plants grow, they get bigger, and the proportions of your display become unbalanced.  What was once very pleasing to see is now top heavy and wrongly proportioned.  This may also mean that your plant display becomes unstable too - if your pot is not large, or heavy enough, your plant might be prone to falling over, which at worst will damage the plant, and will almost certainly make a mess on the floor.  On the other hand, make sure that when you do report, your new pot isn’t too big, otherwise it will look bottom-heavy and make your plant seem puny.

houseplants in different size pots to show proportions

 

How to repot houseplants

What you will need

  • Compost.  See our recent article on houseplant compost for guidance on what type to choose.  You could use an inert medium such as Seramis or vulcaponic substrate if you wish.
  • A new decorative pot
  • Some LECA (light expanded clay aggregate) granules if you have some.  Most garden centres will sell it in their houseplant section, or you can get it online
  • A pair of rubber gloves (optional) - you may wish to wear gloves when handling compost

items you need to repot a houseplant

What size pot?

Your new decorative pot should be approximately 20% bigger than the old one in diameter and depth.  So if your plant was previously in a 15cm pot, you should look for one about 18 cm in diameter. If your old pot was 25cm in diameter, your new one should be about 30cm in diameter.  The height of the pot should increase proportionately.

progression in pot sizes

Does it need drainage?

Many gardening writers will insist that houseplants need to be in pots with drainage holes that need to sit in a saucer or decorative pot.  This is not really necessary.  It is absolutely fine to plant straight into a decorative pot (as long as that pot is waterproof), as long as you get the watering right.  See our recent article on watering house plants here.

Plants in a foli8 coir pot

It is unlikely that you will need to repot a foli8 plant just yet as we have only been selling plants for a few months.  However, in due course, your plant will grow and will welcome a new home.  When it does, repotting is simplicity itself.

  1. Take your plant, still in its foli8 coir pot, out of its decorative pot.
  2. Get your new pot.
  3. Add a layer of compost (or an inert medium such as Seramis or vulcaponic substrate if you wish) or Leca to the bottom of your new decorative pot.  Add enough so that the plant in its folio8 coir pot sits on it with the top of the pot just under the rim of the decorative pot.
  4. Pack compost around the sides of the foli8 coir pot up to the top. Top up the compost in the foli8 coir pot if necessary (it may well have shrunk).
  5. Water your plant, ideally by adding water around the edge of the pot rather than in the middle.  In due course, the plant’s roots will grow through the foli8 coir pot and into the new compost.
  6. When the plant needs repotting again, just lift the plant out of its pot and plant up in a new decorative pot in the same way.

repotting plants in a foli8 coir pot

Plants in a plastic nursery pot

If your houseplant is currently in a plastic nursery pot, then repotting directly into a decorative container is pretty straightforward, especially if you follow the top tip of creating a perfectly-sized planting hole.

  1. Make sure your decorative pot is completely waterproof and the right size.
  2. Take the plant out of the plastic pot and place carefully to one side.
  3. Add a layer of compost, an inert medium such as Seramis or vulcaponic substrate, or LECA to the bottom of the decorative pot.  Use the nursery pot to gauge the depth, so that the top of the pot is just below the rim of the new decorative pot.
  4. Place your nursery pot on the layer of LECA / compost. Make sure it is not off-centre
  5. Pack compost (or an inert medium such as Seramis or vulcaponic substrate if you wish) around the edges of the nursery pot (you might wish to put some compost in the nursery pot for stability) and firm it in place.
  6. Remove the nursery pot.  You now have a planting hole that is exactly the right size for your plant.
  7. Take your plant and gently tease the roots out from the dense rootball.
  8. Place your plant in the grow pot (make sure the green end of the plant is pointing up).
  9. Gently firm the compost around the rootball and top up the pot with extra compost if necessary.

repotting plants in plastic nursery pots

If you wish to keep your plant in a nursery pot, just follow the instructions above and instead of direct planting into the decorative pot, just use a larger nursery pot and put the planted nursery pot into your new decorative pot.

Big plants

If you need to repot large plants (e.g. those in decorative pots over 30cm in diameter), then you may wish to consider setting up a home-made subterranean irrigation system.  This system is often used by professional interior landscapers and is very easy for the home gardener to do.

You will need:

  • A large waterproof decorative container, at least 10cm deeper than your current container
  • Some LECA (light expanded clay aggregate) granules. Enough to fill your new decorative container to a depth of 10cm
  • A piece of capillary matting (available from garden centres) or hanging basket lining fabric, cut to fit on top of the LECA layer.  Cut a hole approximately 4 cm in diameter towards the edge.
  • A length of plastic pipe approximately 4 cm in diameter (available from any DIY store) and cut to a length approximately 5cm less than the height of the decorative pot.
  • Compost: enough to fill the container when firm
  • A pair of rubber gloves (optional) - you may wish to wear gloves when handling compost 

To plant up:

  1. Remove your plant from its old container
  2. Take your waterproof decorative container and add a layer of LECA to a depth of 10cm
  3. Place the capillary matting on top of the layer of LECA
  4. Insert the plastic tube through the hole in the matting into the LECA. make sure it doesn’t protrude above the rim of the decorative pot
  5. Take your plant and place in the centre of the new decorative container
  6. Fill around the edges of the plant’s rootball with compost and firm.  You may need to add a layer on top as well.
  7. Make sure that the pipe is kept clear.

To water the plant, carefully pour water down the plastic pipe.  For guidance, a 40cm diameter pot will need approximately 3 litres of water.  Depending on the plant species, you will only need to water once every 3 - 8 weeks (I have a 1.5m tall Schefflera arboricola set up on a system like this, and it is watered once every two months. My very large Sansevieria trifasciata, which has over 30 leaves, is watered noi more than four times a year).  For the first month or two, you may need to top water as well.  After that time, enough water will have soaked into the soil from below to create a nice moist zone of compost just below the roots.

a semi-irrigation system for big plants

Special rules for particular plants

Some plants have more particular needs than others.

Orchids

pink and white orchid

The most common houseplant orchid species is Phalaenopsis, or the moth orchid.  These are inexpensive as well as beautiful and it is now possible to get good examples from supermarkets and garden centres as well as from specialist orchid nurseries.

These plants rarely need repotting, but you might wish to put them in a different decorative pot for aesthetic reasons.

When repotting orchids, you should keep them in their nursery pots which, you will notice, are made of clear plastic.  This is because the roots of orchids need exposure to light.

If the new decorative pot is much larger than the nursery pot, place the orchid pot on a layer of LECA and make sure that any of the fleshy grey aerial roots are able to sit on top and not get buried or crushed under the nursery pot.  You can add some more LECA to stabilise the pot if necessary.

Cacti and succulents

Cacti and succulents have a fairly shallow root system, so it is not necessary to repot into deep containers. Wider, bowl or saucer shaped containers are ideal.  The method of repotting is exactly the same as described above, although you may wish to use a coarser, grittier compost mixture.

Dracaenas in plastic nursery pots

Dracaena plants (dragon trees) are usually two or three rooted canes planted together in the same pot.  The roots are very wiry and they don’t form a dense rootball that holds itself together, unlike many other plants.

When repotting dracaenas that are growing in plastic nursery pots, a useful trick is to keep them in their original nursery pot (or one just a little bigger), with the bottom cut off.  This will act as a supporting collar for the roots and the bottoms of the canes, and allow the roots to grow down into the new compost.  Eventually, the new root growth expand into the compost and form a denser network.

repotting dracaenas in pots

Dracaenas in foli8 coir pots can be repotted the same way as any other plant that is grown in a foli8 coir pot.

 

By Kenneth Freeman

 

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