I’ve always loved repotting! Working with soil made me feel like being in contact with nature. I know not everyone shares my enthusiasm for getting dirty, but repotting is one of the most important activities for a plant’s health:
Why do you have to repot houseplants?
Plants use nutrients from soil for their growth. After some time the potting mix will become deficient – in one or more nutrients. When the soil gets deficient in one nutrient, this prevents the plant from growing to its full potential. By repotting you are providing fresh, nutrient rich soil, so the plant can grow into the best version of itself.
Mineral salts accumulate in soil from fertilizers and tap water. As they accumulate they start damaging the roots. The best way to remove them is repotting.
Potting soil compacts over time. As it does, the roots stop receiving sufficient oxygen. By repotting you are providing fresh non-compacted soil, with plenty of oxygen.
How do you know if your plant needs repotting?
When you buy a plant, very often you get a plant that already has roots coming out through the drainage holes. Sometimes the roots curl up at the soil surface. These are signs a plant needs repotting.
Roots of some plants are so strong they can deform or break a pot. This is the case with tuberous plants or plants that grow from rhizomes, such as snake plants or ZZ plants. Their roots are just so strong that over time they cause plastic pots to bend. If a pot is deformed or broken, it’s time to repot.
Another way to tell it’s repotting time is if the soil is drying out much faster than it used to. If you have a plant which took 10 days to dry out and now it takes only 3-4 days, pull the plant out of the pot and inspect the rootball. If you see a lot of roots and not a lot of soil, it’s time repotting time.
Even if you don’t experience any of these situations, I still recommend repotting all plants every year or two, to reduce soil compaction, salt accumulation and nutrient deficiency.
Is there a bad time of year to repot?
Not really. Imagine wearing shoes that are two numbers smaller. Do you wait for the next season or do you buy bigger shoes as soon as you can? You know the answer 😊
It’s similar with houseplants. If a plant is in a tight container, you generally want to give it room to grow as soon as you can. If it’s nutrient deficient, you should give it new soil so it can continue developing. Also, if there is salt accumulation, the longer you leave a plant in this soil, the more the roots will get damaged. If a plant needs repotting, I suggest you do it as soon as you get a chance.
How to repot properly?
Ideally, wait until the soil dries out, it will be easier to take the plant out of the pot.
Make sure you know what plant you have and which type of soil it needs – regular potting mix or a succulent/cacti mix.
Always amend regular mixes with at least 20% perlite, vermiculite or pumice. Since these materials do not decompose over time, they will help maintain the soil structure with lots of oxygen. And roots need oxygen to be happy.
The mix that I like to use (the one in the video below) is:
Select an appropriate pot by getting the next pot size. If your plant is in a 4” pot, get a 6” one. If it’s in a 10” pot, get a 12” one. If a pot is too large, it will contain too much soil, which would take a long time to dry out and can slowly lead to root rot.
I suggest only using pots with drainage holes. While it’s possible to grow beautiful plants in pots with no holes, it’s not something I would recommend to beginners.
There are two ways to repot a plant – potting up and full repotting. If you’re a beginner, start with potting up.
Potting up means you move a plant with its roots and existing soil into a larger container and fill in the space around the plant with additional soil.
Start by filling 1/3 of the new pot with soil. Take the plant out of its pot and lightly loosen the rootball before putting it in the new pot. Don’t worry if you cut off some of the roots in the process, the plant will be ok. Then fill the remaining space with soil and press it firmly around the plant. Make sure the plant is potted at the same depth as before. And leave an inch of space between the soil and the pot rim, so there is room to water.
As you expand your knowledge and gain confidence, you can try full repotting.
Full repotting means once you get the plant out of its original pot, you should remove all of the soil or most of the soil from the roots. Once the plant is bare-rooted, inspect the roots and remove all dead and rotting ones, encircling roots, fine roots that made what I like to call “a carpet” at the bottom of the pot. Then repeat the remaining steps from the potting up process – fill 1/3 of the new pot with soil, put the plant in and fill the remaining space with soil. While full repotting is a bit more advanced repotting process than potting up and can stress some plants a bit, it provides a lot of long term benefits for the plant – you are keeping the whole rootball healthy and oxygenated, promoting new root growth and providing the most optimal environment that will ensure long term health of your plant.
Remember that healthy roots are the basis of a healthy plant.
Some plants, peace lilies or oxalis for example will get visibly stressed after full repotting, but a lot of houseplants tolerate this type of repotting well and show no visible signs of stress.
After repotting, water the plant so the soil can settle and get in contact with the roots.
Is it ok to prune roots? Will it harm the plant?
Root pruning is a normal part of repotting where you remove dead and diseased roots, encircling roots and roots that have formed a “carpet”. Encircling roots and “carpet” roots will eventually start to constrict themselves, restricting the flow of water and nutrients.
It is also ok to cut off some healthy roots. For example, sometimes I don’t want to repot a plant into a larger pot even though it outgrew its existing pot. I might not have space in my home for a larger pot. In that case I will do a full repot of the plant, but I will cut off a few inches of healthy roots. This is perfectly fine. I wouldn’t recommend cutting off more than 30% of healthy roots at a time, as you don’t want to stress out the plant too much. And you want to leave the plant with enough roots to be able to support all the stems and leaves.
Root pruning promotes root branching. Similar as when you cut a plant stem, plant roots will generally branch out at the point of the cut.
Remember that healthy roots are the basis of a healthy plant. There is a big difference in the longevity of an average houseplant tree and for example of a bonsai tree. The difference in their life expectancy i.e. 5 years for a houseplant vs. 200 years for a bonsai tree is in the way the roots are treated. Healthy roots and proper root management are the reason why bonsai plants live hundreds of years.
I hope my advice will help you repot your plants with more confidence. Enjoy the process!