How and when to pot on chilli seedlings

Here we go again. The seeds have germinated, true leaves are growing. All seems well. And then, suddenly it dawned on us that these precious babies might need a bit more than a teeny tiny pot and seed compost. What next?

Reporting, ready to POT ON, Sir!

Have a look

A seedling that is ready to pot on for the first time will be showing certain key signs:

  1. It will actually be growing. Smaller leaves becoming bigger leaves. The plant will be getting taller. New leaves green up. Plants just sitting there, existing with two seed leaves, sulking, are not ready for a bigger pot yet.
  2. The water is being used up quickly in the first pot. Another sign the plant is growing well and using what you give it.
  3. Maybe a root or two are poking out of the bottom. Chillies like to be potted on incrementally. Not straight into a whopping great 20L pot. The surest sign they’re ready to move home is little white roots peeking out underneath.

Get prepared

The seedlings will wait a couple of extra days whilst you prepare their new home. Get the next size pot in from the cold shed/garage/backdoor step/unheated greenhouse. Bring in any soil that is going to used and let it warm up. Prepare your work station, table coverings, labels, pens, dibber, watering can, chilli feed, trays, capillary matting. It’s like preparing for the arrival of a new baby. Get all the kit sorted in advance. We all have our preferences but make sure you’ve got all your fave tools to hand. We like a teaspoon and a chopstick at this stage.

Your pot of choice will depend on your preference and circumstance. We have been collecting and reusing 9cm square pots at this stage for some years now. These suit us for many reasons: they come to us via purchases at a favourite nursery (West Kington Nurseries name check)… friends and family give them to us…they fit together with no spaces… they fit well on the trays we use on our window sills in the Winter months… easy to stack and store… easy to keep clean… good to write on with chalk pens for labels… discourages roots from going round and round…durable and last for a number of years. Some of our pots are easily seven years old, if not older. Virtually family.

Pick a pot that works for you.

Ahh, but what type of soil?

A free draining soil mix will suit chilli babies

Much has been written about soil type. Lots of advice is out there. Last season we spent many hours researching, sourcing, combining, mixing and using a very special Birdhouse Mix. It all seemed very important at the time. You can read our 2019 soil post here:

https://birdhousechillies.com/2019/02/06/the-quest-to-find-the-best-soil/

But this year, we are doing things a little differently. We have saved and are reusing the Birdhouse Mix soil from pots last year. *Gasp* I hear you all draw breath. It is not the done thing according the the Wise Growing Elders. And it is certain that some of you will just plain disagree with our actions. No problem, we all garden our own way. However, in this day & age of recycle, reuse and reduce, it surely makes sense to reuse the soil we so lovingly created. So we are.

If we’re not convincing enough then why not listen to Alys Fowler, gardening extraordinaire.

https://www.theguardian.com/lifeandstyle/2019/may/18/how-to-reuse-old-compost-alys-fowler

So how to ensure the old compost is put to good use…and is actually good for our chillies?

Check the texture. Is it good and friable (best word EVER)? Rub through any clumps as if making pastry. The baby chilli roots need air around them and need to be able to push through the soil to spread out. Fluff the soil up nicely for them.

Check the content. Are there pests, seeds, twigs, berries, fungus, or other microbes that could cause harm to the new plants? If so, discard. Pick out any old roots. Our soil store is directly under a gargantuan Holm Oak tree. Great volumes of waxy leaves fall into the soil. They too have to be picked out. Grrr!

Check your intentions. Do you intend on feeding your plants? (Yes!) A liquid feed is perfect for reused compost. If not then you may need to add a general fertiliser or want to consider a more nutritious soil to start with.

Check any supplements. Some people add water retention beads. You may want to add grit, perlite or vermiculite (or cat litter, Alys). Good drainage is best for chillies. Our soil mix has plenty of grit, sand and perlite already so we just added a 10% of peat free multi-purpose compost, just to add bulk and a touch of all round nutrients for the next few weeks. We also add a layer of horticultural grit at the bottom of each pot to avoid the roots sitting in anything too wet.

Are we ready to pot now?

Potting on and on and on

And now you can pot on. This is how we do it:

  1. Select your first seedling, check which variety it is and label its new 9cm square pot. We use chalk pen.
  2. Put a layer of horticultural grit in the bottom of the pot, followed by a layer of lightly damp, warmed soil.
  3. Our seedlings are in newspaper pots. Then can just be popped on top of the soil layer.
  4. Back fill around the pot. If the seedling is leggy then top the soil up until just under the seed leaves. Gently not to damage the stem as that could cause weakness later on.
  5. Pick up the pot and gently knock it on a surface to settle down the soil without compacting it. Top up if need be.
  6. Place the pot on a tray lined with capillary matting.
  7. Water with a weak feed. Warm water, from the base.

Presenting the Class of 2020 in their new pots

Of course a chilli head’s work is never done. Here are the rest of the Class of 2020. Chinense on the right, gradually putting on bulk. On the left are the late germinators. Mostly Annuums so they should be fine. All too little for new pots yet.

Not quite ready to pot on.

Pinching out, plants, progress and potting on.

The last few weeks have been busy. Spring has finally sprung in Hampshire. The garden is waking up and our Family and other Animals are demanding attention. The chillies have been quietly doing their thing on the window sill. After a sunshine-tastic Easter Bank Holiday it is time for a progress report.

Potting on…

Roots were starting to appear at the bottom of the smaller pots. A sure sign it is time to pot on. Not too big too soon or the plants will spend all their time growing new roots to fill the massive pot and forget to grow up top.

The same mix of soil was used. Seemed to work well for the first round of pots so why change it? No need for staking any plants yet. This time last year the Jalapeños and Big Bombs were already needing a small stake to stop them flopping over. Topping has helped the plant stability.

86 plants potted on. Very satisfying.

As a result of topping…

The plants have responded well to their growing tip being pinched out. Some plants were showing signs of branching anyway but others, less natural spreaders, have really bunched up and sent out side shoots galore. Excellent work. Although none of the topped plants have flower buds they all have many, many more growth points, rather than one leading spike.

A comparison of topped and not topped plants show significant differences (significant to us, anyway) Topping has slowed flower development, created more leaves, bushier and shorter plants. The non-topped plants are destined to be sold at a Summer Fete. They are tall, flowering plants with big leaves. They should do well in their new homes.

The late-to-be-sown Rocoto plants have just been topped. They are rapid growers and have a good number of true leaves. Snip snip snip. Time to bush out.

Last year the solo Rocoto plant we grew was a real pain in the greenhouse. Sprawling and brittle, it decided it needed other plants to support it. This made moving them around almost impossible. It was definitely worth the hassle (as is clear from the last minute seed planting) but there is nothing wrong with attempting to keep them more compact this year.

Rocoto chilli plants freshly topped.

Moving up to the greenhouse…

The plants been up in our heated, bubble wrapped greenhouse for nearly a week and the results are good. All round light, controlled temperature and gentle air flow has really allowed the plants to flourish. We’ve been trying to keep the temperature above 15 degrees at night, so far no problem, despite outdoor temperatures hovering around zero. Temperatures during the day are less than perfect. It can often be well over 35 degrees in there, with window and door open. We’ve attempted some strategic placing of the hotter types on the South side and the ones that are less tolerant of high temperatures on the North side or somewhat under the shelving. Generally all the plants have added a couple of extra sets of leaves and are looking tip top.

There are a selection of plants that will be gifted to friends and family. These are not necessarily going to be potted on or placed in prime location though, just kept ticking along. They will be left in their first pots or potted on into odds and sods pots. A good chance to clear out any unwanted pots. These are in the cold frame, covered over at night and will be fleeced if a cheeky frost makes a surprise appearance.

Potted on ready to sell at the school Summer Fete.

All the Trinidad Perfume plants are showing good growth but have odd looking central new leaves. Pale and crinkly. Investigations and results will follow.

Trinidad Perfume plants showing signs of nutrient deficiency. Time to investigate.

Time to consider the feeding regime again. Should we increase the Chilli Focus mix to 10mls per litre? Should we go to twice a week or stick with once a week? Is an Epsom Salt spray needed again? And what about banana tea?


Potting on the seedlings

A lot has happened since things kicked off this year. Our seeds were hot housed in the steamy propagator in the hope that germination would be quicker, more consistent and we would be a bit more successful with the chinense types. And things have indeed gone well. Hundreds of seeds germinated, hundreds of paper pots were made and now it is time to pot on the strongest of the plants to a more substantial home.

Paper pots
Germinated chilli seeds in their forever paper pots. Some seedlings just showing their leaves

How do we know it is time to pot on?

The seedlings are starting to show roots through the bottom of their paper pots. Many have two or more sets of leaves. The sun is shining in the UK and is forecast to be so for at least a couple more days. Perfect for a bit of window sunbathing to help the chillies settle in to their new pots. All good signs.

Seedlings ready to pot on

Using the specially formulated potting compost mix, the plants are tucked into 9cm square black pots. A layer of grit is put in the bottom and the paper pots are not removed, just buried within the new pot. Minimal root disturbance and the plants hopefully don’t feel swamped by the new pot.

Hey presto, 151 seedlings are potted on, fed and watered and basking in the sun.

Sunbathing in their new pots

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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