How to Germinate Seeds

Seeds are a natural wonder; what other natural process captures gardener's hearts and minds like germination.

How to Germinate Seeds

Seeds are a natural wonder; what other natural process captures gardener's hearts and minds like germination. The sprouting of seeds has a genuine mysticism to it. As a gardener, you hope the gardening gods are with you and live in excited anticipation as you wait to see the green shoots of seedlings emerge.

Like all great gardening skills, germinating seeds is a mix of getting the science and art right. There are fundamentals to follow to improve your success when it comes to sowing seeds but also the art of applying your observant eye and tender loving care.

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.

Also, who among us does not love an abundant mass of plants? I am an unabashed plant maximist. More – indeed, the MORE - the merrier. Or the more plant gems to share with other plant people. Seeds are one way of propagating a mass of plants economically. Also, unlike plants, seeds can be stored in their dormant sleeping state in the right conditions to share and sow in the future. Often we have sown seeds and failed, but I urge you to try and try again. Seeds have all they need to get started and germinate with a tending hand. It is best to think of the seed as a 'dormant plant'. A new plant's potential lies in wait ready for the 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. For great success with seeds consider these three fundamentals for germination; moisture, sowing depth and soil temperature.

Moisture

All seeds need moisture to start the process of germination. The seed coat absorbs water, the seed embryo enlarges and - ka boom - out breaks the root (radicle) followed by the shoot (plumule) which develops into the leaf and stem. The art of seed sowing is to water regularly (1-2 times per day depending on the weather) so the seed never dries out once sown. Avoid sitting the seed punnet in water as if waterlogged the seed can rot or will not be able to absorb oxygen which both seeds and roots need to develop. Use your pinkie finger in 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 to the container's base, encouraging those roots 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 do the trick.

Light and 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. So beautiful broad beans will be sown roughly 2 cm deep into the soil, while our 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. Let's not make it too hard for them. It would be best if you were a bit more vigilant on the sowing of finer seeds, as being that bit closer to the surface, it easier for finer seeds to dry out. The use of a see-through propagation lid or cloche can assist in maintaining moisture levels.

Soil temperature

Seeds have evolved to germinate at particular soil temperatures, summer fruiting and flowering plants, i.e. sunflowers and tomatoes need soil or our seed raising mix a minimum temperature to germinate successfully. It is less essential for flowers and vegetables, which flower and fruit in cooler months, i.e. sweet peas, poppies, Asian greens, peas etc. The summer flowering and fruiting seeds need warm soil or seed raising to germinate; about 20-21 degrees celsius is ideal. 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; grandparents have sat seed trays on the top of hot water services in the past, or find other warm locations or make a greenhouse in a well lit warm room or window sill. 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 our plant babies, so keep containers clean before sowing. Good quality seed raising mix is important, or make your own with a fine texture, which holds moisture and is free draining. A blend of worm castings, fine coir and sand can work but clean the sand first (even bake it in the oven to remove any cheeky weed seeds).

There is a whole world of germination wonder, research and techniques like stratification, smoke water and scarification, out there awaiting you in the sowing of trickier seeds, once the fundamentals are down pat. Gardeners experience the magic of being 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.

Indirect Sowing

Use the indirect sowing method to get an early start on the season, especially if you live in a cooler climate with shorter summers and want to grow tomatoes, eggplants and capsicum.

Make sure you use clean punnets or quick pots. Jiffy pellets and coir pots can be planted directly into the garden, without disturbing the roots, where they will break down over time.

Seeds that can be sown successfully as seedlings include tomatoes, eggplants, capsicum, broccoli, onions, celery, leeks, stevia, parsley and small flower seeds like delphiniums.

  1. Fill your punnet or pot with seed raising mix.
  2. Fill to the brim and firm down the surface.
  3. Sow seeds carefully. Cover with fine layer of seed raising mix.
  4. Gently water in.
  5. Place in a well lit position.
  6. Transplant when they have grown their second set of leaves.

Problem Solving

Sowing seed is incredibly rewarding but can also be challenging due to seasonal fluctuations and other variable factors.

Use this table to help you succeed. 

PROBLEM  RESPONSE
Seeds dry out between sowing and emergence of the first ‘seed’ leaves. It’s critical that consistently moist soil is maintained, preferably with a fine misting. or gentle spray (Diggers bottle top waterers are ideal) as strong water flow or heavy rainfall can dislodge or wash away shallow seed. 
Pest attack Protect your seeds from insects and critters such as slugs, possums and rabbits as they can destroy seeds as soon as they are sown.
Non-viable seed Ensure seed is stored correctly (not exposed to light, extreme temperature fluctuations or moisture) and is planted prior to its use-by date.
Incompatible soil temperature Particularly relevant for Tender crops that won’t germinate if soil temperature is below 15°C. Be sure to sow in the soil temperature ranges listed with each crop. 
Sowing seed too deeply  Sow seeds no deeper than twice their width. 
Seed burn after sowing Use only well-rotted and fully composted soil improvers in garden beds, as fresh manure may cause seed damage. 
Poor propagation hygiene Ensure punnets and pots are sterilised using hot water and use fresh seed raising mix for each sowing. If direct sowing, be aware of chemical residue risk in imported soil and practice crop rotation to avoid disease build up.