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Pepper Sowing and Growing Guide

Published: 25th April 2023


In order to give your peppers long enough to mature within the summer months, seeds need to be sown from the middle of February. Sweet peppers can be sown at the latest end of March, for chilis the middle of March.


A kitchen windowsill or a heated propagator is perfect for germination. You can use either a seed tray (with or without grids), or a few small pots – filled with a seedling specific compost. Make sure you moisten the compost before planting your seeds. Plant your seeds evenly apart from each other with at least 2cm between each seed and sprinkle with a dusting of compost on top. Cover the seeds with a plastic bag if they are on a windowsill – this will keep the conditions warm and moist. If your seeds are in a heated propagator this won’t be necessary.

Sweet peppers and chilis need to be kept very warm in the germination period. A temperature between 20-22 degrees Celsius is optimum.


Prepare to transplant your seedlings after about 2-3 weeks. Your seedlings should have 2-3 leaves on them before you consider moving over to pots. 9cm pots are perfect for pepper seedlings, and they can stay in these for up to 6-8 weeks. Your peppers will still not withstand being outside at this point and will need to be kept inside on either a windowsill, in a conservatory or moved into a greenhouse/cold frame. Plants should not be moved outside into a non-heated greenhouse/cold frame before the mid-end of April. Peppers have no frost tolerance and will not survive in a non-heated greenhouse or a cold frame if there were a cold snap.


Once your peppers start to outgrow the smaller 9cm pots, you can move them into their final pot/grow bag/polytunnel.

Follow these general rules for acclimatizing your pepper plants.

- From a heated greenhouse or window ledge – into a cold greenhouse or cold frame

- When in a cold frame or greenhouse slightly open the lid/open the window during the day and close at night for the first week

- Over the next two weeks gradually raise the lid of your cold frame or keep the window/door of your greenhouse open more consistently. Then you could consider moving your plants outside.


The peppers should be harvested when the fruit is swollen and glossy. This would normally be from mid-Summer and into Autumn for plants grown indoors and from August into September for plants growing outdoors.

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