How to harvest seeds
SEEDS OF LIFE
Seeds are small miracles, capsules of dormant life that can last a long time. Indeed, the seed of the date palm Phoenix dactylifera was germinated 2,000 years after it was created. Some seeds, on the other hand, can be short lived, for example the semi-parasitic yellow rattle plant Rhinanthus minor, which prefers to be sown fresh so it can catch the frosts that come in winter to aid germination.
After pollination, plants put a lot of energy into developing seed to ensure survival. Each seed contains everything required to germinate into a seedling, including carbohydrates, fats, an embryo and a specialised seed coat called the testa. The testa is sensitive to water, temperature, pH, light and sometimes even smoke. When the conditions are right, the testa breaks, allowing water to enter the seed. It then swells and this triggers germination. The radicle bursts out first, spreading downwards to form the roots, and this is then followed by the plumule, emerging upwards to make the shoot, out into the open air. Germination really is an extraordinary process.
WHY GROW FROM SEED?
Seed grown plants have many benefits:
- It is very economical as you can grow multiple plants from one seed packet or – even better – harvest and grow your own seeds from the garden.
- Home-grown seeds will be better adapted to your local climate. We call this ‘seed provenance’ – where your seeds come from. Plants will be more resilient to local climatic conditions, pests and diseases, meaning you have stronger plants.
- Direct-sown plants root efficiently into the soil compared to container-grown plants – this eliminates root damage and transplant shock.
- There is a huge range of plants available to grow from seed, including heritage varieties of fruit and vegetables.
- They are environmentally friendly, requiring far fewer resources to produce.
- Growing from seed can be very satisfying, promoting a sense of achievement and improving mental wellbeing.
WHAT TO GROW?
You can grow almost anything from seed, although some seeds will be easier to grow than others. Some of the easiest classic seeds to grow include poppies, calendula and nasturtiums.
There is a huge range to consider including:
- Ornamental grasses.
- Perennial herbaceous plants such as lupins, eryngiums and aquilegia.
- Shrubs such as lavender, mahonia and hazel.
- Trees including oaks, silver birch and maples.
- Bulbs such as camassias, tulips and alliums.
- Cacti grow well from seed too, and are easy to grow on a sunny windowsill.
With a little patience and care, you can grow anything from seed.
Worthwhile seed companies I use: Chiltern Seeds, Kings Seeds, Suttons, Fothergill’s and She Grows Veg – all available online or in garden centres.
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HARVESTING
Seeds develop and ripen as the growing season comes to an end, so in the UK this usually means looking out for ripe seeds from June to September. You will start to see brown seed heads with dry seeds forming, although you must watch out as some seed capsules have evolved to explode such as geranium and euphorbia, flinging their seed far away from the mother plant. You can wrap small cloth bags over the seed heads to collect these seeds.
Throughout summer, observe your seeds ripening and when they are darker in colour, loose and ready to drop select a dry sunny day and start harvesting. Snip off seed heads and deposit into labelled envelopes ready to process later in the garden shed.
Remember to leave some seed heads for birds and wildlife. Leaving seed heads is important for the ecosystem and it is amazing how many insects live in the seeds and rest over winter for next season.
SORTING AND STORING
Your seeds will need a little sorting, but this is a peaceful and mindful task.
Method:
1: Break up and crush tight seed capsules to release the contents. This can be done with kitchen cutlery on white paper, allowing you to gently separate the seed from the chaff.
2: Lift the paper slightly, gently pushing seeds away from chaff.
3: Discard the chaff then store in small brown envelopes, labelled with name and date.
4: Store in a sealed container or biscuit tin and keep in a cool cupboard or the fridge.
You could try winnowing. Winnowing is an ancient technique of shaking the seeds and chaff from a height with a slight breeze. This allows the heavier seeds to drop and the lighter chaff to blow away. Lighter seed such as foxgloves, parsley or dill can be winnowed.
GERMINATION
My top tips for growing seeds:
1: Order seeds over winter ready for the following spring.
2: Mimic the conditions of how and when the plant grows in the wild, e.g. foxgloves and forget-me-nots set their seed in June/July and scatter them lightly across the ground. Sow these seeds in summer, sowing lightly on the surface of level compost.
3: Seeds like variation in temperature from night to day, stimulating the seed coat to break. Avoid sowing seeds in a central heated house, allow them to experience greater temperature fluctuations outside or in the greenhouse.
4: Some seeds such as malabar spinach or sweet peas benefit from scarification. Break the seed coat down manually with some sandpaper. This allows water to enter, speeding up germination.
5: Give your seeds plenty of sunlight.
6: Use a seed compost (lower in nutrients and more free draining) for best results.
7: Water sparingly and do not allow to dry out.
8: Follow the advice on the seed packet or research via books/internet..
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