Seed compost generally contains fewer nutrients than all-purpose compost (as too many nutrients can overwhelm seeds in the initial growing stages), but a high amount of phosphate, to encourage root growth. It often contains leaf mould, coir, or a similar substance, in place of peat, and is finer in texture, so shoots can easily break through.
Sand or perlite in the mix can help to ensure the compost has good drainage. A decent seed compost will encourage your seeds to germinate and grow, during the early stages. It is designed to promote the formation of strong root systems, and can usually be used for cuttings too – although you should always check the requirements of the species, before planting.
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To help you choose the best seed compost for your new plants, we’ve put together this list of our 5 favourite options on the market, based on their nutrient composition, texture, user-friendliness, and value for money. With one of these specialist composts, your seeds are sure to flourish.
These discs of dry seed compost expand with water to provide the perfect, compact growing medium for your seeds
Our favourite option for sowing seeds is this Pack of 100 Nutley’s 22mm Compost Plug Pellets. These dry compost discs contain the perfect combination of nutrients, to provide the ideal growing medium for your new plants.
Unlike conventional compost, these pellets come pre-divided into convenient amounts, ready to be placed in a seed tray, or in individual pots, and sown with seeds. They are incredibly compact and easy to use, and perfect for novice gardeners, or those who want to avoid waste.
The 22mm plugs expand when they come into contact with water, to allow them to accommodate your seeds. The small size means you can plant lots of individual seeds (up to 100) in one space. However, bear in mind that even when fully expanded, the discs are still small, and may not be big enough for larger seeds, such as peas.
For starting off smaller seeds though, these compost pellets are hard to beat. They provide your seeds with everything they need for the best start in life, and come in a highly user-friendly form.
- Provides the ideal growing medium for seeds.
- Pack of 100 discs means you can plant up to 100 seeds.
- Easy to transplant the whole plug to soil once seeds are germinated, with minimal disturbance to roots.
- Can be used in seed trays or pots.
- Easy to use – perfect for beginners.
- Take up very little space.
- Discs are small, and may not be big enough for larger seeds – check the size before ordering, to make sure they’re suitable for you.
- Some users report that their plugs started to go mouldy.
This peat-free potting compost contains coconut coir, and is highly affordable – but you will need to keep an eye on the moisture level
This 10L Organic All-Purpose Potting Compost from Greenbrokers Ltd is a great value option, for those who want the freedom to use as much, or as little, compost as needed for their seeds.
The compost is delivered dry, and expands to a volume of 10 litres when combined with water. This makes the bag small enough to be easily transported and stored, and is perfect for those users who might struggle with a heavy bag.
To activate the compost, you simply cut open the top of the bag, pour in 3 litres of lukewarm water, leave to absorb for 5 minutes, and it’s ready to use. If you don’t need 10L of compost at once, you can separate out a smaller amount, and save the rest for later. The compost has a long life, which means that you can use it when you need it, and avoid waste.
The formula contains all the essential nutrients for plant growth, including nitrogen, phosphate and soluble potash, and has a pH of 5.2 – 6.8. It’s produced from natural raw coconut coir material, and doesn’t contain any peat, which makes it more environmentally-friendly.
It is a dry compost, and you will need to keep an eye on the moisture level, and water it regularly. Ultimately though, this is a great choice for anyone looking for a natural, organic seeding compost, that doesn’t take up too much space, for a highly affordable price.
- Organic, all-purpose potting compost.
- Contains essential nutrients for plant growth.
- Produced from natural raw coconut coir material.
- Peat-free formula is more environmentally-friendly.
- Small bag is easy to carry, transport and store.
- Long-life means you can use it as you need, avoiding waste.
- Compost dries out quickly, and will require regular monitoring and watering.
- Can be a little difficult to separate into smaller amounts.
- Some reports of plastic pieces in the soil.
This seed and cuttings compost contains vermiculate and wood fibre, as well as a wetting agent, for superior moisture retention
Our next option is this ForestGold 10L Seed & Potting Compost from YouGarden. This specially-formulated compost is ideal for potting seeds and cuttings in containers.
The texture of this compost is particularly light and fine, which is great for seeds, as it’s easier for young shoots to break through, and helps to encourage root development.
The formula includes vermiculite and fine wood fibre, and contains everything your seeds need to begin growing. It also contains a wetting agent, which helps the compost to retain water.
It is delivered in a 10L bag, which is re-sealable, so you can use as much as you need at any one time. The bag has a built-in carry handle, to make it easy to lift and move around.
Gardeners have used this compost to successfully start all manner of plants, including tomatoes, lettuces, cucumbers and peas, from seeds or cuttings. We’d recommend it for anyone looking to start growing their own veggies from scratch, and become more self-sufficient.
- 10L of compost for seeding and cuttings.
- Encourages fast germination and root development.
- Contains vermiculite and fine wood fibre.
- Wetting agent helps with water retention.
- Fine texture is ideal for growing shoots.
- Bag is easy to reseal and carry, thanks to the built-in handle.
- Some users report that the compost attracts bugs.
This sustainable, peat-free seed compost is made from wool and bracken, and has excellent water retention abilities
If you’re looking for a high-quality, natural seed compost, check out this Dalefoot Wool Compost. The formula is entirely peat-free, which makes it considerably better for the environment.
It consists of a sustainable mix of bracken and wool, which comes from sheep at the Lake District National Park, where the compost is manufactured. Wool contains a high level of potassium, which is essential for plant growth, so it makes an excellent medium for your seeds.
The wool also helps to make the texture of the compost similar to peat – it’s fine and crumbly, which makes it ideal for seedlings, as their shoots can move and grow freely. It has excellent water retention qualities, and won’t dry out as quickly as some of the other composts on this list.
With 12 litres included in the pack, this is also our largest quantity of seed compost, and could be ideal if you’ve got a lot of seeds to plant, or you just want your compost to stretch further. It’s approved by the Soil Association, so you can be sure you’re getting quality, as well as quantity.
Ultimately, this is a fantastic, sustainable option for anyone concerned about the negative environmental effects of mining peat for compost. It’s fine, crumbly, and moisture retentive, and perfect for starting off seeds.
- Large 12L bag will last longer.
- Made from wool and bracken – 100% sustainable.
- Wool comes from sheep at the Lake District National Park.
- Peat-free formula is more eco-friendly.
- Fine texture is ideal for seedlings.
- Excellent water retention – won’t dry out too fast.
- Made in Britain.
- Approved by the Soil Association.
- Compost isn’t designed to expand with water, and the 12L bag is, therefore, larger and heavier than some of the others we’ve featured.
This ultra-fine, nutrient-rich compost is ideal for planting cuttings and sowing seeds and can boost plant germination by 25%
The last option to make it onto our list of the best seed composts is this Gro-Sure Seed & Cutting Compost from Westland. It comes in a 10 litre bag, which is relatively easy to lift, transport and store.
This compost contains a unique blend of plant extracts, including seaweed, to provide your seeds with all the essential nutrients they need to grow, and mycorrhizal fungi, to help build roots. The manufacture claims that Gro-Sure can improve germination by 25%, compared to standard seed and cutting compost.
The formula also contains fine-grade vermiculite, which gives it a fine texture that encourages aeration and drainage, and makes it an ideal medium for sowing seeds. It can also be used effectively for planting cuttings.
A minority of users report lumps of wood in their compost, but these definitely don’t seem to be the norm. If you notice this, we would recommend sieving the compost before use, as a fine texture is desirable when sowing seeds and planting out cuttings.
Overall, we believe this is another high-quality seed compost, that will provide your seeds with all the nutrients they need, and has the fine texture needed for young shoots and roots to break through – and all for a very reasonable price.
- Contains seaweed, and nutrients essential for healthy plant growth.
- Boosts germination by 25%, to give your seeds the best start in life.
- Contains mycorrhizal fungi to help build roots.
- Ultra-fine texture ensures the compost has excellent aeration and drainage.
- Small 10 litre bag is easy to lift, transport and store.
- Compost may need sieving before use, to remove any lumps.
What Is Seed Compost?
Seed compost is a compost specifically designed for propagation. It is the recommended type of compost to use when sowing seeds and planting out cuttings, and will give new plants the best start in life.
This type of compost has fewer nutrients than general garden compost, which can be too rich for seeds. Leaf mould, coir (coconut fibre) and rotted wood chippings are often substituted in place of peat, to achieve the right consistency and drainage for seeds.
Seed compost is also light and fine in texture, to allow shoots and roots to move freely through it. You can transplant your seedlings into all-purpose compost, once their roots have become established.
How To Make Your Own Seed Compost
The easiest option when it comes to planting seeds is to purchase a ready-made seed and cuttings compost, such as those we’ve featured here. These composts are specifically designed to meet the nutritional needs of your growing plants. However, if you prefer to try making your own seed compost, there are several ‘recipes’ you can follow.
One option is to mix equal parts topsoil from your garden and John Innes compost, and then add a handful of Fish, Blood and Bone, and a sprinkling of perlite. Alternatively, you can add an equal amount of leaf mould to your topsoil/compost mix. If you don’t want to use soil, you can also mix two parts compost with an equal amount of coir, and one part of perlite or sand.
Sieve your mixture to remove any larger pieces, and make sure the seed compost is fine. If you really want to go all out, you can also (carefully) steam your seed compost in a pressure cooker, or heat in the microwave or oven, before planting. This will pasteurise it, and kill any germinating weeds. Store your compost in an airtight container, in a cool, dry location.