The Wonder of Seeds (and How to Successfully Germinate Them)
There are few other natural processes that capture a gardener’s heart and mind like germination. The sprouting of seeds is both mysterious and wondrous and there is little more exciting for a gardener than seeing the first green shoots emerge from a tray of freshly planted seeds.
An abundant, delicious world of diverse plants awaits your plant-loving fingertips if you can master the art of seed germination. Quality nurseries offer various plants online and on shelves, but the range will never match what you can source and share in a seed.
Like all great gardening skills, germinating seeds is about getting the science and art right. There are fundamentals to follow to ensure success, but equally as important is the art of applying your observant eye and loving care.
Seeds contain within them all they need to germinate. Think of a seed as a ‘dormant plant’ – a new plant’s potential lies in wait, ready for optimal conditions to crack open and burst out of its capsule.
Seeds can be sown directly into the ground, which avoids any later transplanting, but often we sow seeds into a container like a punnet. When seeds are sown in a punnet, it is easier to create the optimal conditions for a seed to germinate. Seed packets will have general advice on what season to sow and how best to sow directly into the soil or in a punnet with seed raising mix.
If in the past you’ve sown seeds and failed, I urge you to try again. For success with seeds consider these three fundamentals for germination: moisture, sowing depth and soil temperature.
All seeds need moisture to start the process of germination. The seed coat absorbs water, the seed embryo enlarges and, kaboom, out breaks the root (radicle) followed by the shoot (plumule) which develops into the leaf and stem.
Water your seeds regularly (1-2 times per day depending on the weather), so they never dry out once sown.
Avoid sitting the seed punnet in water – if waterlogged the seed can rot or will not be able to absorb oxygen, which both seeds and roots need to develop.
Stick your pinkie finger into the corner of a seed punnet. Is it cool and damp below the surface? If so, no watering is needed.
When watering, ensure water penetrates from the surface right down to the container’s base, encouraging roots to grow downwards. Misting and spray bottles don’t cut it. The surface will look damp, but water will not have been absorbed in the seed raising mix right to the base. A watering can with a fine rose or bottle top waterer will do the trick.
Light & Sowing Depth
Some seeds will need light, and others will start the germination process without it. The sowing depth is essential. Use the width of the seed as a rule of thumb. Sow the seed as deep as the length of the seed. For example, beautiful broad beans will be sown roughly 2 cm deep into the soil, while finer friends like poppies and lettuce seeds can be sown on top of the soil or seed raising mix and will settle in after a watering. Minimal, if any, soil or seed raising mix is required on top.
If seeds are sown too deep into the soil, they may not be able to crack through to the surface with their resources. Don’t make it too hard for them! Also, be vigilant when watering fine seeds – as they’re close to the soil surface, they’ll dry out much faster. The use of a see-through propagation lid or cloche can assist in maintaining moisture levels.
Seeds have evolved to germinate at particular soil temperatures. For example, summer fruiting and flowering plants such as sunflowers and tomatoes need soil or seed raising mix at a minimum temperature to germinate successfully. Temperature is less essential for plants that flower and fruit in cooler months such as sweet peas, poppies, Asian greens, peas etcetera.
For summer flowering and fruiting seeds try to keep soil/seed raising mix at around 20-21 degrees Celsius. This warmth can be artificially created with a heat mat which sits underneath seed punnets and radiates heat directly up to the seed raising mix. Alternatively, grandparents have sat seed trays on top of hot water systems in the past! In cool climates, find a warm location in a well-lit room or sunny windowsill or even make a greenhouse. As long as the seeds are cosy as we head into spring, germination will improve.
Recycling containers is great, but do clean them thoroughly between uses, so no diseases hang about. Punnets are like nurseries for plant babies, so keep containers clean before sowing. Good quality seed raising mix is important – it should have a fine texture, hold moisture and be free draining. You can make your own with a blend of worm castings, fine coir and sand. Make sure you clean the sand first (even bake it in the oven to remove any cheeky weed seeds).
See The Diggers Club Seed Sowing Guide for step by step advice.
There is a whole world of germination wonder, and plenty of research and techniques – like stratification, smoke water and scarification – awaiting you as you progress towards sowing trickier seeds, once the fundamentals are down pat.
Gaining an understanding of the fundamentals of sowing seeds is a magical opportunity to be involved in every aspect of a plant’s lifecycle – from germination to cultivation and finally, saving the seeds for the following season. It is a precious natural wonder we gardeners are lucky enough to experience.