In their natural environment, plants live in soil, on trees, or in bodies of water. They are connected to the flow of water and nutrients, absorbing these primarily through their root system.
With houseplants, we are simulating this natural environment inside the plant pot through soil that contains nutrients, air and moisture. Over time, the plant roots will grow, the nutrition will decrease, and you may need to consider repotting your plant. In the process of repotting, you may decide to increase the pot size, which is called “potting up”.
Let’s take a look at these two plant care activities:
- Repotting involves changing the existing soil for the plant, conditioning the roots and placing the plant back into the same pot that it came from. This method is great for plant health and freeing-up root space. You can use this method when you need to provide the plant with fresh nutrients, but don’t need to or want to increase the pot size.
- Potting Up simply means that you increase the pot size in the process of re-potting the plant. This is usually done when your plant needs more space to grow.
With potting-up, an additional step is added to the repotting process, which we will explore below. Let’s first take a look at the signs that tell you that repotting is required.
7 PLANT SIGNS SHOWING YOU WHEN TO REPOT
You may need to repot if your plant:
- roots are pushing the plant up and out of the planter
- is growing slower than usual, and it is not in its dormant phase, or not growing at all
- is very top heavy and keeps falling over
- soil dries out quickly and needs more frequent watering (soil to root ratio is low)
- height is more than 3 times the size of the pot
- hasn’t had a soil change in 12 - 18 months
- roots are showing significantly out of the bottom of the pot
These are the signs that indicate that you may need to repot.
DO ALL PLANTS LIKE TO HAVE A LOT OF ROOT SPACE?
The challenge with root bound plants is that the roots grow in a circle, in and around themselves, suffocating the plant from oxygen and reducing the ability for it to absorb nutrients. Some plants however do well when root bound. Peace Lilies, Mother in Law’s Tongues, and the Ficus genus - these are examples of plants that enjoy their roots being bound. Be sure to google what your plant likes, and decide from there.
WHEN NOT TO REPOT?
When your plant is under stress due to over-watering, under-watering or under an attack of pests or diseases, changing the growing medium at such a time will add further stress to your plant. First deal with the problem before considering repotting, as these actions are not the solution for these problems.
WHEN IS THE BEST TIME TO REPOT?
The best time to repot is at the beginning of spring or during summer, on a mildly warm day. It’s best not to repot during the cooler months as plants go into dormancy and generally don’t like to be disturbed.
While it’s best to repot every 12 - 18 months, some slower growing plants can go for even longer periods without needing any repotting (just a top layer of fresh soil now and then), while young, fast growing plants usually need to be repotted once a year.
3 REPOTTING STEPS
Follow these steps to Repot your Plant:
- Remove the plant from the pot and gently loosen the root ball. Remove any excess soil and gently shake away the soil.
- Examine the roots carefully and clip off any brown, black (slimy = overwatering and dry, popcorn-like = underwatering) or visibly damaged roots with a sharp sterile shears. Healthy roots look white and bright! Trim away about 1/3 – 2/3 of the root mass (starting from the bottom and sides) – so that it fits back into the pot with room to grow (or if the plant is root bound) and gently comb out the roots so that they are loose and free. Clear old soil from the existing pot and clean the pot with hot water.
- Place the plant into the pot and fill it with fresh soil. Gently press down to ensure that there are no air pockets and lightly water until the soil is moist, but not soggy.
It’s at this stage, that you may either be done. Or you may decide to increase the pot size by potting up.
POTTING UP YOUR PLANT
When would you decide to pot up during repotting?
- Generally speaking, if you would like your plant to grow bigger
- If you are looking at changing the planter-pot size proportion
If this is the case, pot up your plant by following the Repotting steps 1-3 above, and adding a larger pot.
CHOOSING THE CORRECT POT SIZE
Generally, when potting up, ideally increase the pot size in ±5cm increments. e.g. a 15cm pot would go to an 18cm or 20cm. A 30cm pot would increase to a 35cm pot.
Increasing the pot size beyond this introduces the risk of overwatering with a soil to root ratio that is too high.
4 SOIL TYPES: CHOOSING THE RIGHT ONE
Choosing the right soil mix is important during the repotting process. While there are many different types of soil, we’re only going to briefly discuss 4 types below:
- Well-draining soil mixes often has bark mixed through it and is excellent for air circulation and moisture retention. This soil is suitable for general indoor plants and most succulents, although a cactus mix is better suited for cacti purposes.
- Cactus or succulent mix often has sand, such as riversand, mixed through to create excellent drainage to prevent the plant from rotting due to too much water retention.
- Peaty mix soils usually have a large amount of sphagnum peat moss and peat moss. These hold moisture and release it slowly to keep the roots moist for longer periods. This soil is great for plants that always need humidity and need their soil to stay lightly moist, e.g. Ferns and Calatheas.
- General purpose potting soil – this type of soil is generally made up of a variety of components including composted tree bark, peat moss and perlite and can be used for general indoor plants, e.g. Crotons and Aglaonemas.
Repotting is an essential part of a house plant’s lifecycle. Do it at the right time, and you’ll enjoy a healthy, happy plant for years to come!