Best soil for indoor plants 2024: Keep your houseplants looking healthy all year round
From multipurpose potting mix to specialised orchid, cacti and succulent soils, we’ve got the best indoor plant soils right here
It can be really tricky and time-consuming researching the endless varieties of indoor plant soil on the market in order to pick the best one. But resist the urge to just pick up the first bag that catches your eye, because house plant soil – or indeed any soil – is more complex than it might appear.
The majority of houseplants need to be planted in a dedicated potting mix. This will include all the necessary nutrients your plants need to grow, along with the ability to provide both water and oxygen to the plant’s roots.
Depending on the plant in question though, a standard multipurpose ‘do it all’ potting mix might not be the optimum medium for good growth – orchids, for instance, need plenty of root aeration, while cacti love a free-draining compost. If you want to grow these plants, you’re advised to either buy specialist compost mixes or make the additions yourself, by adding growing mediums like vermiculite, perlite and coconut coir to your potting mix.
One of the major issues with buying potting soil online (or anywhere, really) is trying to judge the quality from afar without getting your hands dirty. That’s why it’s a good idea to keep track of recent reviews as there are occasionally sub-par batches floating around. In the roundup below, we’ll explain the different components of a typical houseplant potting mix, along with the possible additions you can use at home.
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Best soil for indoor plants: At a glance
- Best multipurpose soil: Growth Technology Houseplant Focus | £8.80
- Best potting compost for orchids: Westland | £8.33
- Best potting compost for cacti and succulents: Miracle-Gro | £9.27
- Best perlite substrate: PLANT!T Perlite | £9.51
How to choose the best soil for indoor plants
In order to thrive, houseplants need their soils to tick some key boxes, such as delivering moisture, aeration, nutrients, and allowing sufficient space for roots to grow, as well delivering the appropriate drainage. Which of these take priority will vary depending on the indoor plant concerned. But one thing’s for certain: you must avoid using (or mixing in) outdoor soil or compost. That’s because it’s far too heavy and thick for delicate root systems, is unlikely to allow sufficient drainage, and is likely to contain pests, bacteria and other nasties.
For houseplants, ideally you’re looking for either a potting mix (sometimes called a ‘potting medium’) or a perlite-based one. A multipurpose potting soil will usually work well with most indoor varieties, but it’s worth knowing there are also specially formulated soils available, designed for potting up cacti, succulents and orchids, and even carnivorous plants.
Alternatively, there’s nothing stopping you from adding a few different extra ingredients to a multipurpose mix, in order to make it better suited to a particular plant’s needs.
What does potting mix contain?
Along with a compost base, most potting mixes contain a combination of the following:
Vermiculite: As a growing medium, the advantages of vermiculite granules are that they quickly absorb water, and also readily release it. This allows for good soil aeration, which encourages roots to spread and reduces the watering schedule, by keeping soil moist. Vermiculite is best used for thirsty plants that need lots of moisture to grow, like pothos, spider plants and ferns.
Perlite: The majority of plants do well with perlite, as it keeps soil well-drained and aerated. It’s a similar medium to vermiculite but holds less water. A good tip is to buy a bag of perlite and add a few spoonfuls into your potting mix – this makes it much harder to accidentally overwater!
Peat moss: There are some environmental concerns with using peat moss but it’s impossible to overlook its superpower…its remarkable absorption rate. Peat moss holds about 20 times its own weight in water, quickly absorbing water-borne nutrients which it can then feed back into the soil.
Coconut coir: The fibres from coconut husks provide added water retention and natural drainage, meaning they’ll stop plants from getting too much moisture. Using coco coir is also more environmentally friendly than using peat moss. Coco coir is best added to potting soil for plants that don’t need much water and benefit from fast drainage, like succulents and plants that thrive in arid conditions.
How often should I repot my indoor plants?
All potted plants will need repotting at some stage as soils eventually lose their nutritional value. While the exact time frame depends on the type of plant, a good rule of thumb is to repot every 12-18 months.
As well as replenishing the plant with new soil, it’s worth considering whether you also need a larger pot, to allow more space for growing roots. Regardless, it’s imperative that you remove as much of the old soil as possible from the roots when you repot.
The best time of year to repot a houseplant tends to be spring, as roots are actively growing and will benefit from the addition of fresh soil. If you want to repot in autumn or winter, be aware that your houseplants are likely to be in a dormant phase and may not respond too happily to a change of environment.
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The best soil for indoor plants you can buy in 2024
1. Growth Technology Houseplant Focus Repotting Mix: Best multipurpose potting soil
Price when reviewed: £8.80 for 8l | Check price at Amazon
Growth Technology’s Repotting Mix is particularly well suited for a wide range of houseplants thanks to its carefully judged composition of coir, loam, bark and vermiculite.
When potting up with Houseplant Focus over the years, we’ve always found the consistency really easy to work with: there are never any big chunks of organic matter present, and water drains through easily from the outset with too much compacting. The soil is invariably moist when opening the bag, and we’ve had no encounters with bugs or pests,although quality will invariably change from bag to bag.
This repotting mix also comes in smaller 2l and 3l bags, making storage easier to manage if you have less space at home. There’s a peat-free variety available too, although the confusingly similar packaging makes identifying it trickier than it should be.
2. Westland Orchid Potting Compost Mix Enriched with Seramis: Best potting compost for orchids
Price when reviewed: £8.33 for 8l | Check price at Amazon
Orchids are famously temperamental houseplants to care for, so it makes sense to use a potting mix specifically designed for their needs. The Westland Orchid Potting Compost mix is an open compost that contains pine bark for increased airflow and to help roots from getting too wet.
Like many of Westland’s products,this one also contains SERAMIS granules. These plant granules (made from clay) are powerful enough to replace potting soil, absorb water well and help with root aeration. A 8l bag of Westland orchid compost is enough to fill two 14cm pots if you’re a dedicated orchid grower, but it also comes in an 4l bag.
3. Miracle-Gro Premium Cactus, Succulent & Bonsai Compost: Best soil for cacti & succulents
Price when reviewed: £9.27 for 6l | Check price at Amazon
Cacti and succulents need soil that contains plenty of grit and sand, as this allows water to drain freely and so helps avoid waterlogged roots. Trying to find this balance using your own mixture of ingredients, however, can involve a lot of trial and error so it’s much easier to use a specialised compost mix, like this one.
It’s formulated with a slightly acidic pH that’s suits cacti and bonsai, along with plenty of sand to encourage drainage and aeration. Although this compost doesn’t really need other mediums mixed in, some customers have found it can get quite heavy and saturated, thanks to the proportion of sand in it. If you find that’s the case, you can always add a little perlite or a handful of small stones for extra drainage.
4. Wilko Coco Potting Compost 40L: Best coconut coir compost for indoor plants
Price when reviewed: £4 for 40l | Check price at Wilko
Dehydrated compost, commonly using coconut coir, is a relatively new arrival on the houseplant care scene, and a welcome one since it takes up far less storage space. This Wilko coco potting soil expands to a whopping 40 litres, yet weighs much less on arrival: simply add warm water to a small quantity of the coco coir and wait a few moments for the soil to expand to a fluffy consistency. While Wilko instructs you to add 16L water to the full bag of compost in one go, we’ve had success rehydrating smaller amounts by ‘gestimating’ the measure of water needed.
Coco coir is best used for seedlings and early starts, since it doesn’t have much nutrient value on its own. Alternatively, bulk it out by mixing in various other substrates. Be aware that coco coir does dry out faster than regular potting soil, though, so you’ll have to adjust your watering schedule accordingly.
5. PLANT!T Perlite 10l Bag: Best perlite substrate for indoor plants
Price when reviewed: £9.51 for 10l | Check price at Amazon
For indoor gardeners keen to experiment with using add-in ingredients to their potting mix, this perlite from PLANT!T is a great choice. It’s a natural and sterile growing medium that easily breaks up heavier soils and maintains aeration for roots.
We tend to add a couple of spoonfuls of it to potting soil and mix it together before filling the pot; this way the soil remains loose and won’t compact around the plant when it goes in. It’s important to remember that perlite is 100% inorganic and doesn’t contain any nutrients, so it does need to be combined with soil or compost to work. You can also use perlite for outdoor plants, too: it’s particularly useful when establishing root cuttings, and can even help aerate a newly laid lawn.
The 10l bag goes a long way and, though lightweight, it’s worth noting it does take up a fair amount of space. For truly industrious users, there’s also a bulk-buy 100l bag available for under £26.
6. Carbon Gold Biochar Houseplant Booster: Best soil booster for houseplant growth
Price when reviewed: £9.99 for 1l | Check price at Crocus
If your houseplants are tired, wilting or looking a little worse for wear, their soil might be in need of a helpful boost. Carbon Gold Biochar is an organic form of high-carbon charcoal that improves the quality of pre-existing soil, helping with aeration, nutrient retention and overall structure. Simply put, this stuff will rejuvenate your plants from root to tip.
While it’s perhaps a little onerous for repotting the occasional singular houseplant (instructions say to add 1-3 teaspoons of the product for every litre of potting soil), using Carbon Gold Biochar is a great all-round option for improving your plants’ health. Consistency wise, it’s a rich dark colour and really easy to work with, not leaving dust or residue. We really appreciated its arrival in a compact tub, too – a welcome departure from the usual tricky-to-store large bags of compost.
