Propagating seedlings means simply germinating seeds and growing the seedlings until they are big enough to be planted into a bigger pot, or directly into the ground. Sound easy? You can make £600 per month doing it if you’ve got green fingers and some warm space.

You might wonder why people pay for seedlings and don’t just do it themselves, but propagating seeds is the most fiddly bit of growing plants and needs fairly specific conditions (lots of light and warmth) so not everyone has the space or the patience to do it. You can take advantage of this and create plants that you can sell at car boot sales and at local garages and shops or to friends and neighbours. In some country areas people leave potted plants outside their front gate and trust passers-by to put money in the tray when they take the plant away.

• What you need
• How do I do it?
• How long will it take?
• How much can you make?

What you need

• Compost

The first thing you’ll need to propagate seedlings is some really good quality seed compost. There’s no hope for your seeds if you just go outside and scoop up some earth from your garden as its physical structure just won’t be up to scratch and it will also be host to lots of pathogens which will cause problems later on for your new seedlings. But you don’t want potting compost either as it has too many nutrients and puts your seedlings at risk of fertiliser damage, plus it provides a lovely environment for liverworts and moss, which will then compete with your seedlings for water, space and light. A good soil-based seed compost is the answer for seedlings that are going to take a few weeks to germinate. For plants that grow rapidly, you can just use a soil-free organic mixture.

• Seeds

Then you’ll need the all important seeds. You should not try propagating seedlings from old seeds; buying fresh ones every year isn’t very expensive and will ensure that you grow the best quality seedlings possible. Also, some plants need to be germinated from fresh seedlings and old seeds will simply not grow. So make sure you do your research to get the best results.

• A place for the seeds to grow

Finally what you need is a place to grow your seedlings in. This means some seed trays, and somewhere warm and humid. This could be a greenhouse, a conservatory or even just a propagator (a seed tray with lid a bit like a fish tank), but your seedlings need to stay protected from the cold at all costs otherwise they will not make it.

• Other stuff

You’ll also need a watering can. Some seedlings may need other special treatment, so make sure you read the seed packet carefully.

How do I do it?

Different seeds need to be planted in different ways – this information will be included on the packet when you buy your seeds. The things that differ according to which plants you want to grow are how many seeds to sow, how far apart to sow them, how deeply they need to be sown and whether you need to use any extra fertiliser or not. All seedlings will need warmth, light and water but there should be other instructions on your seed packet or on websites such as the Royal Horticultural Society.

How long will it take?

Seedlings can take between four and six weeks to grow their second set of leaves, which is when they will be ready to be sold. If you want to sell them as ready to plant outside, you’ll need to wean them off the warmth by putting them outside for longer and longer during the day to acclimatise them to the cold gradually. This takes time and seeds are often not big enough to go outside until they have been re-potted anyway, so you need to choose which size seedlings you want to sell. You’ll probably get more money for bigger seedlings in individual pots, but this obviously will mean a bit more expense and more time.

How much can you make?

You can make in the region of £600 a week by propagating seedlings, with just a few hours’ work a week. However, the work is seasonal – mostly between February and October – so you won’t be able to make this much every month. The amount you make also depends on how much space you have to grow the plants. The more space you have, the more you can grow and the more money you can make. There are ways to improve your profits:

• Pick the type of plants you are going to grow carefully. Some seeds cost £2.99 for six and some cost £2.99 for 1,500. You do the maths.
• Try to get discounts on all your materials. For example, you can try and do a deal with your local garden centre to buy the pots that they would usually throw away for a discounted price, making your unit cost lower and your profits bigger.
• Try selling to both business and individuals. Selling to a business will give you a steady income but the unit price will be lower. However you can get a higher unit price from selling to your friends and neighbours or even at a car boot sale. So by doing both, you can maximise your profit.

Want to know more?

• Grow your own fruit and veg
• More on growing: RHS
• Channel 4 Growing guides
• See what other people are doing to make a bit on the side – visit our money making forum.