If you haven’t started sowing seeds indoors on a windowsill or under a grow light, in the next few months you may soon be. Especially if the itch to get sowing becomes too much to deal with during January.
The Winter season seems to have shifted in the UK from December to January & February but this does not help gardeners who have been gifted seed sets for Christmas and want to get growing!
So Is it worth Starting so early by Sowing Seeds in January? I discussed this last year and my opinion was No, it wasn’t worth it.
My opinion was based on the information I read but I had not tried sowing anything in January so I didn’t have any experience to base my opinion on.
This year – 2025, I definitely have the growing itch so I’ll be trying to sow some cold loving vegetables indoors on the windowsill to see how they go in January and then Sweet Peppers and a new addition Aubergine in February.
Let’s look at what is needed to create a simple seed sowing setup for starting seeds indoors on a windowsill.
If you are on a budget, remember you can buy seeds in small quantities for as little as 50p per packet and on a budget, you can use grocery plastic boxes (fruit) as seed trays.
Scroll down to see more ideas for growing on a budget or introducing seed sowing with children.
Here are some of the items you’ll need to sow seeds indoors on a windowsill.
1. Seed cell tray or Seed Tray
A Seed Cell tray is divided into separate cells so you can sow one seed per cell.
The advantage of a cell tray is that the seedling can easily & quickly be transplanted and roots not disturbed, when you need to pot on to a bigger pot to replenish the nutrients for its continued growth.
For this reason I prefer Seed Cell Trays over Seed Trays. I buy mine from Amazon – Windowsill Seed Cell Tray with Lid (6 pack). I like this set as the cell trays can be cleaned and re-used every year.
This cell tray kit also comes with the tools to make a tiny hole in the compost to put your seed (dibber) and a tiny fork to dig out the seedling to transplant or pot on and a ventilated lid.
A Seed Tray is a tray where seeds are sown, when you need to transplant a seedling. You may need to disturb the soil and other plants & roots when potting on your seedlings. You will need a tiny fork the size of a pencil to dig out the seedling to transplant.
Top Tip
Indoor Seed Trays or Cell Trays need to be the correct size to fit on your windowsills. Measure twice, buy once!
On a Budget – Seed Sowing Trays
- Fruit punnets or plastic trays as seed trays (if the trays have holes in you will need to stand them on a plate to catch drips)
- Egg boxes and half an egg shells, add a small amount of compost to half egg shells, and sit them in the egg box.
- Toilet roll cardboard tubes, can be used as pots. Make sure you add a piece of paper or tissue to make a bottom so all your compost doesn’t escape. These are great for peas, beans and sweet pea flowers.
- Paper cups, take care as paper cups used for drinking hot fluids have a plastic coating inside the cup to make it waterproof. Holes can be added to drain water. If you are transplanting the whole cup outside, remember the plastic inner coating is going with the plant into the ground and may contaminate the soil.
Trying to avoid Plastics? Then try biodegradable versions of Seed Trays & Pots like:
- Bamboo Seed Trays – compostable & reusable up to 5 years. BPA Free (a chemical to make plastic). Approx price for A4 size tray £8.49 from Gardening Naturally.
- Rubber Seed Cell Trays – reusable, plastic free, long lasting & flexible. * Not for suitable for people allergic to Latex. For windowsills, easily cut the rubber to the size you need. 30 cell tray £15.99 (cells 3x3x4cm) Tray size: 29 x 22 x 4.5cm from anythingbutplastic.co.uk.
- Wooden Seeds Trays – these may be good outside in a greenhouse but not so great on a windowsill as they are wide and leak soil.
- Coir Pellets in a tray – these are individual mesh cases with coir compost made from coconut husks. They sit in a tray and you sow one seed per pellet. The pellet including the mesh, then gets transplanted all in one into a new pot or the ground. Great for minimising roots disturbance. Plantable 10 Pellets in a Tray £5.99 at Mr Fothergills.
- Wood Fibre Seed Tray Cells– no plastic, perfect for windowsills, compostable & biodegradable. Require a tray to sit on windowsill. 72 Cells Tray can be cut to size £8.99 from Gardening Naturally.
- Wool Pots – biodegradable, sustainable with no chemicals. These are wool out skins, you add compost to the middle and sow seeds. Then plant the whole seedling plus wool pot into the ground. The wool will decompose and is a natural slug deterrent. 20 Wool Pots – 9.5 x 18cm £16.95 from Mr Fothergills
- Soil Blockers – a piece of metal equipment that forms compost and drainage material into a solid soil block ready for sowing seeds into. This is a messy process until you get the hang of it and is better to use outside in the greenhouse.
2. Seed Tray Lid with Ventilation
The Seed Tray lid will form a heat environment with a few air holes to stop the condensation forming inside the area. This will help the seedlings germinate in the warm.
The lid needs to be removed once seeds have germinated otherwise the soil becomes too wet or too dry or the seedlings become leggy because there’s not enough light under the dome.
If your seed tray doesn’t come with a ventilation lid, here are the budget ways of achieving the same situation.
- A plastic bag popped loosely over the tray,
- A plastic bag with the tray inside so it can be sealed with a few holes made in the plastic,
- If you don’t have a lid or bag, your seedlings may take a little longer to germinate as they haven’t got the right conditions in heat.
3. Pots for transplanting or potting on from Cell trays
When it is time to pot onto your seedlings, you will need the brown or black 9cm diameter pots in the photo above to pot on your seedlings with new compost. Alternatively try coir or jiffy pots that you plant straight into the ground.
You may need to have these on the windowsill for a few weeks on a tray to catch drips. Then you will need to put them outside in an unheated greenhouse to get them used to the colder temperatures outside.
Potting On Recycled Plastic Pots – 9.5cm x 18cm. 18 pots £5.95 at Mr Fothergills.
Plantable Coir Pots – 8cm pots. 22 Pots £7.99 at Mr Fothergills.
Jiffy Pots – 8.5cm Pots. 36 Pots £9.45 at Mr Fothergills.
4. Multipurpose or Seed Compost
If you have some leftover compost, use that for filling the seed tray or cell tray or small pots.
If you don’t want to buy a big bag of compost for just sowing a few seeds, there are a few options:
- Coir Compost Discs – they come in different sizes, you will need to add water to the coir discs so they expand in size. They only contain the nutrients to get the seed to seedling stage and then it needs to be transplanted or potted on into fresh compost. Pack of 10 discs – 10cm (1.5L of compost in each disc) by Thompson & Morgan.
- Enriched Peat Free Seed Compost (coir based) comes with biodegradable bag. Just add 3 Litres of lukewarm water to expand the compost to 10 Litres. ÂŁ6.99 from Mr Fothergills.
- Harvey’s Multipurpose Compost comes in 5 Litres from Amazon – £5.99.
- Westland John Innes Peat Free Seed Sowing Compost comes in 10 Litres from Amazon ÂŁ9.90.
5. A Small Quantity of Seeds
If you are starting to grow vegetables for the first time, you may not want to buy large quantities of seeds or buy expensive seeds.
Recommended – MoreVeg.co.uk
I have always used MoreVeg because their seed is high quality and very reliable on germination. There seed prices range from 60p and ÂŁ3.50 which is incredible value but most in the lower price range.
This means you don’t have to spend lots, just to sow a few seeds.
I highly recommend MoreVeg.co.uk
Seed Supplier – Discounts & Sales
This is the perfect time to grab some discounted seeds as many of the top seed suppliers have discounts or sales on seeds and equipment.
Discounted Seeds:
Suttons Seeds – 10% off Vegetable Seeds
Use discount code: SUSAW240 at the checkout until midnight 31st January 2025 or click here
Thompson & Morgan – 10% off Flower & Vegetable Seeds
Use discount code: TM_TAW321W at the checkout until midnight 31st January 2025 or click here
Mr Fothergills
Offer: 3 for 2 on seed packets, potatoes and propagation equipment.
If you are using other seed suppliers, check they have a registered licence to sell seeds in the UK.
The Animal and Plant Health Agency have a list of Licensed Seed Suppliers in the UK here.
6. Do you Need Grow Lights?
Do you need Grow Lights? No, unless you want to get your seedlings growing quicker than normal.
Advances in technology means you can have an energy efficient setup with LED grow lights with a few seed tray cells in a shed or spare room.
Amazon sell seed cell trays with a UV light attached for a small setup. Find out more here.
View Ivan’s Gardening Allotment – YouTube Video – Energy Saving Grow Lights for more information on Grow Lights.
My Windowsill Growing Setup Indoors
I started sowing indoors a few years ago using grocery plastic containers but now I prefer the cell trays as per photo below.
Last year I bought a Windowsill cell tray kit which has 6 cell trays (more than enough), ventilated lids, plant labels, dibber and digger tool. This is a perfect kit to get seed sowing indoors for only ÂŁ12.99.
This kit can be cleaned and re-used for the next year.
I will be using this kit again to sow my seeds starting 11th January 2025 with Onion Seeds (see my Events – Seed Sow Along page for more details)
Here’s the link, if you want to purchase this seed sowing kit and start your seed sowing with me in January or February.
Windowsill Cell Tray (6 pack) from Amazon.
I use Multipurpose compost peat free which I breakdown any large lumps with my hands and fill the cell tray up with compost outside to avoid mess indoors.
I use the dibber (that came with the above kit) to make a small hole (depending on vegetable seed size) and sow the seed, cover the seed with compost from the cell and water lightly to activate the seeds.
Sow Along With Me
My Seed Sowing Videos will be pre-recorded and released on weekend dates in January and February to give you a chance to sow your seeds when it is convenient to you.
Get a Free Seed Sowing Checklist to accompany each Veg Sowing Video by joining our Facebook Group
Seed Sow Along – Event Schedule
- Sow Onion Seeds – 11 January 2025
- Sow Cauliflower Seeds – 18 January 2025
- Sow Summer Cabbage Seeds – 25 January 2025
- Easy Veg to Sow for Beginners (Beetroot, Lettuce, 1st Early Peas & Spinach) – 1 February 2025
- Sow Aubergine Seeds – 8 February 2025
- Sow Sweet Peppers Seeds – 15 February 2025
The Sowing Indoors Series
Seeds To Sow In January – Indoors
Written by: Tracey Everett – SowGrowHarvest.co.uk