The quest to find the best soil

Just which compost to choose for our precious chillies?

Loam. Peat. Coir. Grit. Vermiculite. Sand. Clay. Silt. Perlite. Manure. Compost. Sand. So much to consider.

The options are a little overwhelming but let’s dig down to what we know about chilli plants to see if we can come up with our perfect potting medium.

Cultural roots

Considering the geographical heritage of our chilli plants should hopefully give some guidance to the type of soil required for perfect chilli production. Chillies originated from Mexico. They gradually became mainstream as part of the Columbian Exchange in the 15th & 16th Centuries. A large percentage of the soil in Mexico is shallow to medium depth, dry, free draining, not layered or super structured, contains gravel, often fertile, pH leaning towards acid: 5.5-6.5. (Food Agricultural Organisation for the United Nations state that Leptosol, Regosol and Calcisol make up nearly 65% of the soil in Mexico if you want the scientific terms) Replicating this soil composition seems like a good starting point for creating the perfect chilli compost.

Back here in the UK

However, where chillies come from is not the only factor in soil choice. Surely where they are actually going to grow plays a part too. The UK offers a dizzying range of soil types, some of which would be incredibly inhospitable to a poor little chilli plant. Our Hampshire soil is about 6 inches top soil and then solid chalk. Not sure what our chilli amigos would say to that. A slightly acid, sandy loam in the South Hams of Devon would be perfect for growing chillies in the ground. With that in mind, we will be planting in pots.

Our UK weather is such that too much organic matter, such as peat or manure, silt or clay could easily become water logged and get cold. No one likes a soggy cold bottom, especially not chilli plants.

The potting soil in question will have two main functions for our plants: 1. to provide a habitat for our chilli roots to do their thing. 2. To be a vessel for the chemical requirements for great plant growth and chilli production. Let’s tackle each function separately.

A cosy home

We want the roots to have plenty of space to stretch out. Soil is typically 50% solids (mineral and organic) and 50% spaces, about half of which is occupied by water and soluble and suspended nutrients. A light, airy soil, with small particles would match the requirements. The roots can work their way through the gaps.

We will be gradually moving our chillies into progressively bigger pots. They sulk for ages if the pot size goes up too quickly. The indicator that they need to move home is when their roots poke through the bottom. Watering from the bottom should avoid compaction (which leads to a reduction of spaces within the soil available for root growth & essential gas, water and nutrient storage). Perhaps a layer of Horticultural grit in the base of each pot would avoid aforementioned sulky soggy bottom too.

Adding Perlite to the mix is another way to allow the soil mix to stay loose, encourage root growth and water drainage. No rotten roots here.

Feed the need

No great nutrient supply is needed from the soil solids as we will be feeding with Chilli Focus regularly. The organic components of the soil provided by the garden compost will ensure a good supply of microorganisms to exist alongside our chilli plants and work their bio magic. No doubt a few extra seeds will germinate as well but that is all part of the fun of doing things yourself.

We do not want too much green Nitrogen releasing organic matter. We hope to encourage good all round plant health and then fabulous flowering and fruiting. Extra Nitrogen may cause bushy green plants that forget to flower.

The seedlings are currently receiving a weekly feed of 5ml per litre of Chilli Focus. This will increase to 10mls per litre once a week when the plants have been pinched out and show some signs of flowers forming. At the height of flowering and fruiting the plants will have two feeds each week.

Vermiculite is another ingredient to consider. A natural product that is a good addition to any soil type. Added to clay soils it allows aeration and flow through the soil, reducing water logging and stunted or bound root growth. In sandy soils it soaks up water allowing retention where there would be very little otherwise. Good access to water, slowly released, means good access to those soluble and suspended nutrients. Sounds like Vermiculite is definitely going into our chilli mix.

So what does this all mean?

It’s looking like a hand mixed potting medium of 3/10 loam top soil, 2/10 coir, 2/10 organic homegrown well rotted compost, 1/10 grit for the bottom of the pot, 1/10 vermiculite to hold on to water and nutrients between watering and feeds, 1/10 perlite for free drainage within the soil. Probably very similar to John Inness No 2!

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Clean up your act

With the mild weekend weather, we ventured up to the greenhouse for a general clean up. All whitewash was scrubbed from the glass. Floors were swept. Surplus flower pots were removed and stored. Oh, how many there were! Just where do they come from? And why are they ALL different sizes & dimensions? All the odds and sods will be put to good use at the school Summer fete.

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The inside of the greenhouse was given a good wash too. Followed with a vinegar rinse. That should deal with any critters that have taken up residence over the growing season! Dettol was the personal sponsor of the event. And has continued to sponsor the house for a few more days.

A brand new bubble wrapping system of suspension wires. A single wire was hung between the two points of the roof and large sheets of bubble wrap were draped over. This made the task considerably more simple than last year. Snug as a bug in a rug.

Now the greenhouse is ready, willing and able to host the yet-to-even-be-sown chilli seedlings. Current daytime temperature 16 degrees, night time temp was a balmy 10 degrees. Let’s see what happens when the snow fairy has visited.

Chitting Chitting Bang Bang

After somewhat disappointing results from our first attempts at chilli seed germination, the decision has been made to pay more attention to temperature and watering. South Devon Chilli Farm say that 27-32 degrees is optimum chilli germination range and so that is where we strive to be. They also state that surface watering and using warm water are ways to reduce the shock the seeds/seedlings might feel at this delicate stage in their lives. Heard and understood.

Finding a suitably warm (but not too hot) location is far trickier than one would think. On top of a radiator…too hot, 37 degrees or so. On the windowsill…too chilly, 22 degrees or there abouts. In the airing cupboard…too hot again when the heating is on. Back in the heated propagator? Not warm enough with the current weather conditions (snow and an Easterly wind that finds previously unknown gaps around the windows) What to do?

After copious temperature guaging with Old Faithful, the seeds are now, by day, chitting on a sunny, south facing windowsill, above a radiator, and in the bottom of the airing cupboard overnight. Let’s see where that gets us.

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The seeds have been placed into clean, plastic takeaway boxes. The boxes are lined with damp capillary matting. Lids down, one corner slightly askew. No soil involved so we can really see what is going on.

In the previous planting of seeds Aji Limon was the first seed to poke its head above the surface of the soil. Closely followed by Jalapeno. Wonder who will show their face first this time?

Really hoping for some germination from Serrano, Long Hot Cayenne, Tobago Seasoning and Go Chu as there was 0% success last attempt

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