How to choose the ideal container to repot a plant?

Signs your plant needs repotting

• Growth has stopped. The plant is no longer growing (no new leaves, stems or flowers). It has stagnated for several weeks, and this is outside its dormancy period (usually winter).
• The roots are coming out of the pot. They protrude from the top and are no longer buried, or they poke out from the bottom through the drainage holes.

If you notice any of these symptoms, it’s a sign that it’s time to repot your plant!

When should I repot my plant?

Repotting of plants ideally takes place during the plants’ dormancy period. So carry out at the start of spring, or in autumn. For outdoor plants, do this strictly outside periods of frost or drought.

Repotting is usually carried out every two to three years. In the year you do not carry out repotting, you can perform a top-dressing, that is, replacement of the top few centimetres of substrate with fresh substrate. This solution is also considered when the plant is too heavy to move, when it is difficult to envisage a larger container (especially for indoor plants) or when the plant has reached its final size.

A few exceptions may prompt you to repot at other times of the year.

• If you have just bought a new young plant. We recommend repotting all new young plants promptly, the containers in which they grow being generally too small and the substrate having depleted its nutrient reserves.
• If your plant has suffered from a disease or pest infestation. In this case, completely replace the substrate and thoroughly clean the container (it is, however, not necessary to repot it into a larger pot here).
• If your plant is no longer stable in its pot. The aerial parts destabilise the container, which then falls.

Repotting young plants after purchase is often useful

What size should the new pot be?

Finding the right balance: not too big, not too small

The new container into which you will repot your plant must be larger than the previous one. But the idea of “larger” is sometimes quite fuzzy and volumes can be expressed in different ways (in litres or in cm). It is often said that you simply need to choose the next size up: if your plant is in a pot with a 30 cm diameter, opt for a container with a 40 cm diameter. But the size of the future pot depends in fact on additional criteria.

• The overall dimensions of the plant, aerial parts and the root ball (root system surrounded by substrate) Generally, a container 2 to 3 times larger in height and width than these measurements is ideal.
• The growth of the plant. If it is slow as with cacti and succulents, a container 1.5 times larger is sufficient. If it is a fast-growing plant, it is better to choose a container 3 times larger.

Note that a pot that is too large is not desirable, even if you think you’ll save time on future repotting. Beyond aesthetics (the plant will look lost in the middle of its container, so the overall effect will not be very harmonious), many potted plants benefit from being a little cramped to grow or flower well.

Choosing the right shape

You will find containers of all shapes: round, square, rectangular… This is often simply chosen for aesthetics. However, the depth of the container is an essential factor to consider, which depends on the plant’s root development. The average depth is generally 30 to 40 cm.

Some plants require only a little space and substrate to develop, such as houseleeks or other rockery perennials, as well as some annual flowers. These are plants with a superficial root system, staying at the surface. These plants can content themselves with containers, such as bowls, troughs, basins or window boxes of about 10 to 20 cm depth.

Conversely, some plants have a deep and substantial root system. For example, rhizome-bearing plants such as Strelitzia, but also fruiting shrubs and climbing plants. For them, choose containers at least 50–60 cm deep.

Which material to choose?

There are different materials, each with its advantages and disadvantages. They will be chosen according to several criteria:

• aesthetics;
• manoeuvrability and weight (if containers are to be hung or placed on a terrace or balcony);
• durability;
• insulation;
• price.

Terracotta

Terracotta, or clay, is the material we most often recommend using. Terracotta or clay is a naturally porous material.

Advantages:

• it allows the substrate to breathe and water to evaporate quickly;
• containers are relatively inexpensive to buy and readily available in shops;
• they offer good stability;
• they already have a drainage hole;
• it is a natural material with a neutral colour that suits all interior or exterior styles.

Disadvantages:

• it is a fragile material that does not withstand knocks, falls or severe frost;
• containers are heavier, not always easy to move when dealing with large volumes.

Terracotta containers, for example, are suitable for plants that do not like moisture, such as succulents and cacti, Sansevieria, Dracaena, etc. If you tend to overwater your plants, this is also a good solution.

Plastic

Advantages:

• these are the cheapest containers to buy;
• there is a wide variety of colours and shapes;
• they are light, easy to handle and move;
• water evaporates more slowly from them since the material is waterproof;
• they tolerate frost reasonably well and resist impacts.

Disadvantages:

• they are less eco-friendly, although more and more containers are made from recycled materials and manufactured in France (reduced transport carbon footprint);
• they can be unstable if the plant’s above-ground parts are large;
• on some models you have to drill drainage holes yourself;
• their colour can fade with UV exposure;
• Aesthetics are often less featured, but you can place them in attractive cachepots.

Plastic containers are best reserved for plants that prefer moist or cool substrates, such as Alocasia, ferns or Hydrangeas.

Other materials

You will also find ceramic containers. Unlike terracotta, they are coated with a layer that makes them impervious (they are therefore not porous). They are very aesthetically pleasing, but their drawbacks are those of terracotta: fragility and heaviness. In addition, they are expensive to buy.

Containers made of resin, earth fibre or cement replicate the properties of plastic, but are more aesthetically pleasing and offer a contemporary style.

Wooden containers, such as palm tub planters or orangery-style pots, are also quite popular. They offer good insulation against the elements (heat, cold, wind) and are durable. Their natural aesthetic blends easily into a garden or interior. The drawback is that they require regular treatment, are harder to move and their lifespan varies according to the quality of the wood.

Finally, there are metal containers (zinc, aluminium) in trough or basin styles. They add a rustic and vintage touch. However, few have drainage holes already. If you do not want to drill them, we recommend using them as cachepots instead. Also note that when placed in direct sun, they can heat up easily.

Notes: there are self-watering pots, made from various materials. Reserve them for plants that prefer soils that are constantly cool and moist.

Colours

Dark-coloured containers heat up more quickly in the sun than light-coloured ones. They will therefore create temperature differences more quickly, to which some plants are particularly sensitive.

There are pots of all shapes and colours and many materials. While appearance is often a consideration, other factors come into play

Common mistakes to avoid when repotting your plant.

Neglecting hygiene

It is common to reuse old containers for repotting your plants. To avoid any risk of disease transmission, we recommend that you always clean them beforehand. Warm water and black soap are enough to obtain a clean pot quickly.

Choosing an ill-suited substrate

The choice of growing medium is important, since nutrient diffusion is limited in pots. For convenience, you can opt for specialised potting mixes already suited to different plant types. There are for pots or window boxes, for houseplants, for succulents, for orchids, for acidophilous plants, for Mediterranean plants, etc.

Another solution: make your own blends tailored to each plant’s needs.

• For plants that prefer light, well-drained soils, mix half standard horticultural potting compost (or garden soil) with half sand or draining elements (terracotta shards, clay balls, pozzolana…).
• For plants that enjoy rich soils, add a handful of well-decomposed household compost or of specific fertilisers (horn meal, dried blood…).
• For plants needing a humid substrate, add sphagnum moss, which can retain water for longer.
• etc.

Don’t neglect drainage

Drainage is essential to prevent water from stagnating at the bottom of the pot and rotting the roots. Always choose containers with a bottom perforated. For most plants, it is advised to add an extra layer of material to the bottom of the pot (terracotta shards, clay balls…) to allow water to flow away without the roots sitting in it.

The saucer case

Some find it unattractive, but the saucer has several uses when there is no cachepot: it allows the substrate to soak up water by capillary action (especially when it is very well drained). But it also serves to protect surfaces on which the plant is placed (floor, furniture, etc.).

Do remember to empty it after about twenty minutes if there is any water left, to avoid suffocating the roots.

The saucer is useful; it also lets you see how much water the plant has taken up and to empty it if any remains