Which potting compost and soil to use for plants

When your indoor plants are looking for a little worse for wear – and you’ve tried everything under the sun to get them back to their former glory, you can give your leaf babies a new lease on life with potting compost. We’ve got everything you need in your tool kit for repotting as well as ensuring which potting compost and soil you need to repot plants expertly in your best planters and pots.

When looking at our guide, it’s tempting to simply make a decision based on price. However, Geoff Hodge, a contributor for Garden Answers, recommends making “a more informed decision". Make sure to read through our guides as thoroughly as you can. We’ve listed different types of potting compost with different ingredients from a variety of brands at various price points.

Best potting compost at a glance:

• Best potting compost for houseplants: Miracle-Gro, Premium Houseplant Potting Mix Compost - View on Amazon UK
• Best potting compost for succulents: Miracle-Gro, Premium Cactus Succulent and Bonsai Compost - View on ebay
• Best potting compost for hanging flower baskets: Westland, Container Compost Peat-Free - View on B&Q

Geoff recommends experimenting with a couple of different brands to see which compost works best, adding, “It’s only by experimenting that you can discover how each compost ‘works’ – how quickly it dries out, how much water to give, how much fertiliser to add and how often.” You won't need to add much (if any) fertiliser to potting compost, though.

Finally, he adds, “Always buy fresh compost each year. If old compost goes off, it can affect seeds, seedlings and young plants.” We've shared the best potting soils and compost to buy, but scroll down to find out more information on what exactly to look for.

Best potting compost, soil and mix for houseplants

FAQs: Repotting compost

How is potting compost different to others?

The main elements of potting compost should contain materials that will ensure "quick, strong root growth, together with phosphate, which promotes good root development".

Is potting mix the same as compost?

No – there are differences between the two.

Compost is utilised to add nutrients and organic materials to the soil, such as nitrogen, to aid growth. To clarify, regular compost is not recommended for potting (or repotting) and works best dug in existing garden soil. This is because compost starves your poor plants of air space and waterlogs them. Plus, there are no fertilisers added to compost.

Potting mix – on the other hand, is made from organic plant-based material. But, how is potting compost made? Well - alongside additional nutrients and a control-released fertiliser, potting mix is supported by a host of organic elements. To create a potting mix, materials such as bark, coir, peat and pumice are added to aid growth.

How much potting compost do I need?

When repotting your houseplant, you essentially need to make sure you have enough compost to do the job. According to Modern Gardens contributor Martin Fish, there is a secret to repotting your houseplants, which is to “pot up gradually in pot size”. Choose a pot a little larger than the original, basically. "Potting up" is not to be confused with other terms "potting off" and "potting on", which involve getting cuttings started in pots.

For example, if a small plant is in a 9cm pot, Martin clarifies that this should be a “maximum 13cm pot”. Hopefully, with this, the larger planter gives your potted friend "enough room to trickle fresh compost around the existing root ball.”

So, if you’re potting (or repotting) a houseplant, remember these steps to add the compost.

1. Add a little compost to the base.

2. Position the plant in the centre and gradually add the compost.

3. Give the pot a tap to settle the compost.

Why do I need to repot houseplants?

In short, repotting plants gives a growing plant's roots more room. As plants get older and bigger, their roots expand. This is so they can suck up enough water and nutrients to feed themselves. If you choose to repot plants in a stylish new pot with fresh new compost, it’ll help to give them a top-up of the essential nutrients.

Experts advise repotting during the spring and summer when plants are at their strongest. Hopefully, repotting your plants will help them out. But please don’t be too disheartened if they don’t thrive. Just topping up the compost could help some plants. And – some potted plants prefer a large indoor plant pot so they can spread themselves out. It’s worth doing research into your plants.

Here are some signs to look out for when a plant needs repotting:

• It has been years since you repotted the plant
• The plant looks unstable (breaking away)
• Roots emerging from the bottom of the pot
• The plant has clearly grown a lot over time
• The soil looks very dry and dusty

Can repotting kill plants?

It’s true repotting can be a little stressful for your potted plants. So, it's vital to make sure the plant you are repotting looks healthy before you repot them. You should check for root rot and inspect its leaves for any yellow. Unfortunately, repotting can "shock" a plant and can even kill or stunt its growth - if it's not given plenty of care and attention.

Though, for some comfort, it is normal for a plant to experience a brief period of shock when repotted. Here, your plant may appear wilted and thirsty. You can help it out by leaving any watering for a week. This is to ensure all of the roots have spread out, got used to the new pot and repaired themselves after moving.

Can I use potting compost for seeds?

Generally, no. Sowing seeds in potting compost won't do well. A potting compost or 'potting mix' has lots of added nutrients, which can be too much for seeds. You can get specific seed compost for getting started and germination, which contains peat for support with nutrient retention.

Can you re-use potting compost?

The answer is, generally, yes. Most compost types may last for several seasons, at least - if your plant is healthy and did not succumb to any diseases or pests. In this case, you need to dispose of diseased soil.

Further, make sure to inspect your compost bag, though. Geoff Hodge explains, "Compost that has been sitting around for several months may have become ‘sour’ due to the build-up of excess nutrients." To ensure you’re using fresh, watch out for sun and water exposure - and keep your compost covered and away somewhere dry.

What to read next:

Best food for plants to ensure healthy growth

Best plant subscription boxes

Best watering cans that will last a lifetime

Piper Huxley is a Homes, Garden and Wellness Product Writer for Modern Gardens Magazine, an all-rounder. When she’s not writing about houseplants, she’s tending to her own growing collection…