How to choose the best compost for your plants

Compost is the foundation for healthy plant growth. A good compost will contain nutrients, air and water retaining ingredients and anchorage to provide stability for plants roots.

Some people are able to make their own compost. This usually means having large compost making bins or specially built bays where plant materials such as stems, flowers, vegetable peelings, grass clippings etc are added and allowed to decompose after a period of time.

For the majority of people however, compost is what they buy in bag which is then added to the border or bed or used to plant up pots or containers.

Different types of compost

Choosing the right type of compost for your plants depends on several factors, such as the type of plants you're growing, the soil type, nutrient requirements and where in the garden you will be using it.

Compost choice can be broken down into types of plants and specific tasks, but we’ll start with the most common type of compost…

Multi-purpose or all-purpose peat free compost

As the name suggests, this compost has many uses. A good quality peat free compost such as Miracle-Gro Premium Peat Free, can be used for pots and containers, planting in beds and borders, sowing larger seeds and taking cuttings as well as for growing fruit and vegetables. Multi-purpose compost can contain feed that lasts anything from 6 weeks to 3 months and has an open, airy structure with good water retention.

Seed and cutting peat free compost

Although you can use multi-purpose compost for seed sowing, you will get much better results if you use a dedicated seed and cutting compost. This will be finer with less nutrients and will usually contain sand or fine grit, allowing the delicate roots of seedlings to grow down easily into the compost.

The higher nutrient levels in multi-purpose compost can scorch fragile seedlings. Smaller seeds such as chillies and tomatoes should always be sown first in seed compost and then moved into multi-purpose compost once they have grown.

John Innes peat free composts

These are a soil-based compost that can be broken down into 3 stages:

• John Innes No.1 – for seedlings and cuttings
• John Innes No.2 – for planting small vegetables and plants in containers
• John Innes No.3 – for mature plants or those in permanent planting positions

John Innes composts have more weight than multi-purpose due to the grit and loam within them so are an excellent choice for larger shrubs or trees that will be planted permanently in pots. The nutrient levels go up from no1 to no 3, providing the feeding requirements for the different stages of the plants.

Peat free mulches and soil improvers

These are used on beds and borders, traditionally in the autumn or spring to help keep in moisture, suppress weeds and add nutrients. Although not all mulches are specifically a compost many of them will be found in the compost area of a garden centre or DIY store.

Using a specific mulch rather than a multi-purpose compost tends to be a much better option when mulching a large area. Soil improvers can be used in most areas of the garden including as a lawn dressing before seeding a new lawn or just to improve the structure of the soil. Most soil improvers can be used as a mulch, but their main objective is to improve structure and make a clay soil easier to work with and a sandy soil richer in nutrients.

The types of mulch and soil improvers that you can buy can include:

• Farmyard manure
• Lawn dressing
• Top soil
• Garden soil
• Composted bark
• Bark chips

Specialist composts

Ericaceous peat free compost

If you grow plants such as rhododendrons, camellias or azaleas then you will need to grow them in ericaceous compost. These types of plants can only tolerate growing in an acidic soil and an ericaceous compost provides them with all the nutrients they need. Always use ericaceous peat free compost when planting these sorts of plants in containers.

Rose tree and shrub peat free compost

This compost contains extra micronutrients that larger plants kept in long term containers will need ensuring healthier and glossy leaves and abundant flowering.

As you can see there are many distinct types of compost for different gardening needs. Choosing the right compost needn't be difficult once you know what your needs are. Always buy a premium quality, trusted brand rather than the cheapest and then you know that you will be giving your plants and soil the best start.

House plant compost

Many plants that we grow indoors will often need a lighter compost with a more open structure as many of these types of plants won’t like compost that is too heavy or moisture retentive. Within the Houseplant compost range there are also formulations for specific types of houseplants including:

Orchid compost

Orchids tend to grow on trees, known as epiphytes, so need an open structure. The peat free orchid compost is based on bark enabling optimum air and water holding capacity.

Cacti and succulent compost

These plants originate from extremely arid regions so need a very free draining and gritty compost. 

Mediterranean and citrus compost

Although not exclusively grown indoors, especially mediterranean plants like rosemary and lavenders citrus plants such as lemons and oranges will need to spend the colder months indoors and benefit from a free draining specialist compost.

Other composts

Grow your own compost

Multi-purpose compost can be used for vegetable and fruit growing however it is a good idea to use a compost formulated for fruit and veg.

Miracle-Gro Fruit & Vegetable Peat Free Compost is perfect for growing crops that will be eaten, and using a tomato grow bag or planter can save space and be placed near a wall or somewhere sheltered and they will also contain the nutrients needed for hungry veg plants.

Compost for hanging baskets

Multi-purpose peat free compost is usually perfect for pots and containers however hanging baskets and smaller pots which will dry out much more quickly in dry weather will benefit from a peat free compost that is formulated to retain water such as Miracle-Gro Peat Free Premium Moisture Control Compost for hanging baskets and containers.

Bulb compost

Although bulbs can be planted quite happily in multi-purpose compost, to get the best results it is recommended to use a peat free bulb fibre. This will ensure that the bulbs will have good drainage which is especially essential 4 autumn planted bulbs during the winter months when there can be a lot of rainfall to prevent the bulbs rotting.

Because all spring flowering bulbs need to be planted in the autumn, this means that for almost 6 months, these bulbs can be sitting outside at the mercy of all weathers, especially the wetter winters that we seem to be having.

Peat free bulb fibre such as Miracle-Gro Peat Free Premium Bulb Fibre Compost has a very open and free draining structure that ensures that bulbs living in pots and containers won’t rot. The texture also encourages faster and stronger root growth, and the added nutrients help your bulbs last longer, be happier and healthier and are much more likely to flower again the next season.

The dos and don’ts of compost

The dos

• Do choose a specialist compost for the task in hand. This will ensure you create optimum growing conditions.
• Do check your garden soil pH balance before you get planting to see if you have acid, neutral or alkaline soil. This will help you work out what type of plants will work best in your garden. Tests are easy to find online and in garden centres.
• Do use any leftover compost by raking it into your existing soil around your garden as a soil improver.
• Do use fresh compost each year to pot up your existing and new plants as this minimises risk of pests and diseases being carried over. It will also provide fresh nutrients to replace those that have been used up. After planting, always water in your plants (even if the ground is moist) to remove air pockets and ensure the roots are in contact with the soil.
• Do use gloves when handling compost.

The don’ts

• Don’t assume all compost is created equal – you really get what you pay for.
• Don’t sow seeds in standard all purpose compost. For best results use a specialist seed compost that provides for optimum root growth and provides the right plant food to help them develop.
• Don’t be put off growing fruit and vegetables by lack of space. You can achieve healthy crops in pots, hanging baskets and grow bags, even in the smallest of areas.
• Don’t forget that some acid-loving plants such as azalea, camellia or rhododendron will require an ericaceous compost with a lower pH.
• Don’t use your garden soil for potting up containers and baskets.
• Don’t forget to always follow the compost label instructions.