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Best Potting Medium for Chillies

When buying regular potting compost the first decision you’ll face is whether to opt for peat free or not. Peat free has traditionally been the best kind however it is particularly bad for the environment as it is harvested from the natural environment, usually from areas with fragile and diverse eco-systems.

While there are some ethically sourced peat based mediums out there they are usually flown halfway around the world  (places like Canada) so if you’re concerned for the environment, it’s probably best to opt of a peat free compost.

The good news however is that there are now a good selection of peat free composts available at virtually all garden centers. While these have had a bit of a bad reputation in the past they have improved massively in recent years.

Peat composts is very good at retaining moisture where as in my experience peat free composts tend to dry out very quickly. As a result when using peat free you may want to add additional ingredients to adjust the water retention of you potting medium:


This is a natural mineral that has been heated to expand it out into its very light weight form. It’s main attraction is it’s ability to hold on to moisture  and slowly release it and the nutrients into into the surrounding soil over a period of time.

A common problem with plants grown in pots is that daily watering can wash out many of the nutrients from the compost. Vermiculite mixed into the compost will help avoid this problem, particularly if you’re using peat free compost which can suffer from poor water retention. I usually get through 1 bag per year and in my opinion it is well worth the £10 or so it costs.


It is a great drainage aid to compost, ensuring that roots do not get rotten by sitting in excessively wet compost, which can be very useful if you’re using a peat based compost. I also finds that perlite helps prevent the root ball from becoming too compacted later on in the growing season.

Well Rotted Manure

Well rotted manure can be used as a substitute for peat in compost. Not only does it add a huge boost of nutrients to the mix but it also adds structure and water retaining properties to a peat free medium. Just be sure it is very well rotted before using it in order to avoid ‘scorching’ the plants roots.

The Best Chilli Growing Medium

As i stated above everyone has their own preferences however i usually opt for a mix as follows:

  • 70% Peat free multi purpose compost
  • 10% Vermiculite
  • 10% Perlite
  • 10% Well rotted horse manure

I don’t get too fussy about quantities of each and usually work be feel.

Chilli Potting Mix

Moisture Levels

Potting into a dry mix and then giving the potted plant/seeds ‘a good soak’ can cause the compost to become too compacted as the large volume of water rushes through the pot, often taking the seeds down deeper then you want or stealing away nutrients from the roots.

Potting Mix Ready for Use

When either planting seeds or potting on young plants i find it beneficial to prepare (and water) my potting medium a little bit in advance. If i feel the compost is a little dry I usually make my mix up in a bucket (using the quantities above) then water with a watering can fitted with a rose and mix well. I’ll then usually leave it 10 minutes for the moisture to work through and mix again before potting.

9 comments… add one
  • DaveC April 5, 2015, 11:45 pm

    Your site made reading interesting and simple, never having grown Chillies from seed this is my first venture, propagator is a ventilated shoe box with a lid from a high street store, internal growing
    area cake dividers with holes, and seed soil. A bag of 20 MURGANO SCORPION seed and Bonnet seed from a high street store ( 3 for 0.80p), total investment just under £20.00….and I have 16 Murgano seedlings.
    Extra light comes from a diy super bright Led unit, 30 Blue and 10 Red, running of a laptop psu.

    • The Chilli King May 5, 2015, 1:44 pm

      Dave C,
      Welcome to the wonderful world of growing chillies! As usually semi DIY approach tend to do best and are a lot more fun than buying all of the gear straight away! Good luck!

  • Jack February 28, 2014, 3:50 pm

    Thanks a lot! I made a really tiny variation to your mix, as I am growing indoor, so it is:
    80% Peat free Multipurpose Compost
    10% Vermiculite
    10% Perlite

    Here is my germinated seeds: http://www.youtube.com/watch?v=mbwUUz9-MgM

    Thanks a lot for your useful suggestions!

  • Mark January 21, 2014, 9:10 pm

    What grade of Vermiculite should i use or doesn’t it matter?

    • The Chilli King March 3, 2014, 10:09 am

      It doesn’t really matter. I usually just grab what looks good at the garden center!

  • Louis June 5, 2011, 3:53 pm

    can i still use the percentages of soil, perlite and vermiculite without the manure? i.e 80% peat free, 10% perlite and 10% vermitculite

    • The Chilli King June 15, 2011, 11:14 am

      Louis – Yes, that’d be fine!

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