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seedlings

Propagation for Beginners 

To many there is a mysterious world out there where little fairies plant seeds on the right day of the year, by moonlight, chanting songs, whilst sprinkling magic grow fairy dust.

 

In reality nature is amazing and this happens quite naturally every day of every year all over the world all without any human intervention . Plants all have their own way of reproducing themselves. Some need a period of cold which will break their dormancy, others need to be soaked in water or chitted. Birds will naturally sprinkle the seeds or they may even get carried by the wind. The most successful seed sowing happens when the plants natural habitat can be replicated

Propagation really does not need to be a dark art and you really do not need lots of experience.  Seeds packets will all come with sets of instructions and it's best to read these BEFORE you begin.  Some seeds may require soaking to soften the hard outer shell, they may need a period of cold stratification in the fridge before being sowed or may require light to germinate.

How to sow seeds
Beginners seed sowing Guides

Containers

Firstly you will need to decide if you are going to sow into pots, plugs, trays or even coir blocks. Pots are good for large seeds such as Sweetpeas and Zinnia and in particular Sweetpeas do best grown in deep root run pots or even empty loo rolls.

 

Trays are great for smaller seeds such as foxgloves. If you are short of space it is best to sow into trays as they will take up a lot less space, however it will take much more work potting on the small seedlings into larger pots to grow them on before plating out in the garden. Its also worth noting that you can sow most seeds into plug cells trays with anything from 9 - 40 cells which eliminates the need for second stage potting on.

 

With the use of plastics currently under the spotlight many more people are choosing to plant into coir plugs. These are essentially dried out compost plugs which need to be rehydrated in water and can then be planted straight into. They are made from a waste product from coconuts contained in a biodegradable mesh bag. The great advantage of these is that roots do not need to be disturbed when potting on as they can be transplanted directly into their next container or into the ground eliminating the need for plastic pots.

 

Sowing seeds into soil blockers also offers a sustainable and eco-friendly approach to starting plants from seed. These compact and reusable tools create individual soil blocks, eliminating the need for plastic pots or trays. By pressing seeds directly into the soil blocks, you can promote healthy root development and minimize transplant shock when it's time to move seedlings into the garden. This method also reduces waste and fosters a more sustainable gardening practice. 

Soil

To a beginner compost can be an intimidating medium. There are so many on the market and you can also make your own. The idea of a seed compost is to give roots an easy root run so the particles will be sieved quite fine with no big lumpy bits. It needs to provide moisture but not get waterlogged and also provide a little nutrition. Small seedlings only need small amounts of nutrition in the first few weeks as if they get too much they will put on to much lush growth too soon which will attract disease. With this in mind you need to look for a “seed and Cuttings” compost and you will not go far wrong.

You can also make your own seed compost.  By blending leaf mould with other ingredients like compost, coir and perlite. You can customize a seed compost mix that promotes healthy root development and robust seedling growth.

 

Seed compost only contains enough nutrients for the first 6 weeks of a seedlings life. After that seedlings will need to be potted on into a richer mix with more nutrients. A good all purpose compost is all you need for potting on. Beginners should not let themselves get bogged down with all of the fancy words and different types available, however it is worth noting that due to a peat compost ban coming into effect from 2027 most suppliers are already trailing alternative peat free mixes. Some are better than other and this variance in quality arises from the diverse range of organic materials used within the formulations. While peat-free composts aim to reduce environmental impact by avoiding the extraction of peat, their effectiveness can vary based on the specific blend of ingredients. Some peat-free composts may exhibit excellent water retention and nutrient content, thanks to ingredients like coir, composted bark, and green waste. However, inconsistencies in texture, nutrient levels, and pH balance are common challenges, leading to variable performance in seed germination and plant growth. Gardeners often experiment with different brands and blends to find peat-free composts that best suit their gardening needs while supporting sustainable practices.

Gardeners Potting Bench
Using Soil blockers
Caring for seedlings

Sowing Seeds

As I have already mentioned there really is no dark art to seed sowing. When to sow is important, and equally not sowing too early, you can ready more about this on our page about Equinox for Gardeners. 

 

If you are using pots, plugs or trays fill them loosly, tap them down to get rid of any air pockets and then level off the top with your hand or a piece of wood.

 

It is then best to water seed trays from the bottom - you can do this by placing them in a sink with a few inches of water in for a few minutes, they will drink as much water as needed to keep the compost wet for a good few days.

 

You are now ready to sow your seed, and they really do come in all shapes and sizes. As a general rule the larger the seed the more space they will need around them, sow all seeds as thinly as possible. If sowing large seeds into a plug then one per plug is enough. If the seeds are very small then the smallest pinch of seeds possible can be sowed. These may need to be thinned at a later stage. You will soon learn how close is too close when your first carpet of foxgloves begin to emerge. I never ever seem to be able to get these sowed thinly enough and have spent a great deal of time prising them apart, so much so that I now sow them direct into a seedling bed on my plot. I sow then in thin rows and just pull out all the unwated ones. This can seem like a waste but if you have been able to collect your own seed then you will have literally millions of them anyway.

 

Ensure you follow the instructions on the seed packet for how deep to sow and even if they need to be covered. As general rule the larger the seed the deeper they need to be. Some very small seeds do not need to be covered at all and some need to be covered with vermiculite so they are still exposed to light. Follow the advice on the seed packet and sieve the required amount of compost over the top of the seedlings. Using a very fine rose so as to not disturb the seedlings water in gently, label them and then place in a greenhouse or windowsill to germinate.

 

A word of caution on labelling, do ensure that you are using a permanent marker or a pencil. There is nothing worse than all of your writing coming off when watering – most gardeners will have experienced this at some stage and it is truly frustrating. Label each tray/pot with the variety and also the date. This will allow you to keep track of how long they are taking to come up. Particularly troublesome seeds will be mentioned on the seed packet. Some can emerge in as little as a few days and others can take many months of coaxing. The seed packet will also tell you if your seeds need to be kept inside a polythene bag.

While waiting for seedlings to emerge it is best to keep compost on the moist side ( Not waterlogged though) and as soon as the seedlings begin to emerge try not to overwater them, they do not like sitting is cold wet soil, so getting this part right is key. Some seedlings will need to be watered daily and others much less. Keep an eye on the compost as you will be able to see when it has dried out, it will be a much lighter colour than when wet. Seeds will generally need warmth to germinate. Around 16- 22degrees so indoors during the late winter and early spring is ideal if you do not have a heated greenhouse. More advanced growers may use heated mats or propagators to give their seedlings a head start but as yet I am still to invest on one myself and I have been gardening for over 20 years so they are not essential by any means. I do find that the inside of my house is a pretty good environment and we do currently have just enough space for me to keep them lined up on windowsills and tables.

Once the seedlings appear it is best to then move them to a slightly cooler location if possible such as a greenhouse as keeping them indoors after germination does lead to the problem of leggyness. Now most of you will be thinking that this can be a good thing, after all, who wouldn’t want long legs in their life? For plants however this is not attractive or healthy, they put on too much growth, leaning towards the light with thin spindly stems which can not support the leaves. They end up bending over and can also look quite pale. They are simply telling you that they are not receiving enough light. So if you do need to keep them inside the best thing is to chase the sun and move them to the sunniest windowsills possible and turn then twice a day. I only keep mine indoors on very cold days and at night and do prefer to get them out into the greenhouse as much as possible.

 

With this in mind do not be tempted to sow seeds to early. You will just set yourself up to fail, waiting until the days and nights get a little warmer in March will mean that you can leave seedlings in the greenhouse for most of the time and only bring them inside when it is frosty. You will also find that plant which have the best growing conditions will outgrow those which have been planted too early and have stalled their growth due to cold temperatures and the need for more light.

Guide to sowing seeds

Potting On 

Depending on what size of pots you have used and how large your plants are you will find that you will need to thin out your seedlings and pot then on into individual containers or put them into bigger pots. Do not be tempted to re pot very small seedlings as they will just sulk and they are very tricky to handle, as least wait until the first pair of true leaves have formed. You should see that these look quite different from the first leaves of your seedling. This is when your seedlings will need a little more nutrition so ensure that you use a good multi purpose compost not the seed compost you used when you first sowed the seed, this will not contain enough nutrients for your now very hungry growing plants. 

 

So if this is the beginning of your plant journey then good luck, I hope you have found my words both encouraging and useful.  To read more about how to care for your seedlings ready our handy guide Seedling Success.

 

The sun is shining as I write this and my own seedling are calling me to the greenhouse to check on their progress!

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