Let's GROW!

What's in a seed, and how does it bust out to become a plant? TINO CARNEVALE unravels the intricacies of germination, and shares his tips for getting the best results

Aseed is a beginning, but it is also an end – the culmination of days, weeks, months or even years of hard work by a plant to produce something as simple, and yet as complicated, as a seed. As gardeners, we look at seeds depending on the hat we are wearing at the time. If we are sowing we are the nurturing gardener, if we are harvesting we are the hungry gardener, and when saving for the following year we are the wise gardener. Whichever hat we're wearing, seeds connect us to the cycle of life and death.

Spring is a classic time for sowing. With the lengthening daylight and warmer temperatures, even the most occasional of gardeners finds themselves perusing the options in the seed rack. Then it’s out to the garden or the pots on the balcony to sow the seeds… and for those not used to sowing seeds, uncertainty can creep in.

Can I sow straight into the barren plot I meant to plant up last year but didn’t get around to? Does it matter that we’re still getting frost? The pack says full sun but it’s quite shady here. Am I meant to sow into seed-raising mix first? And so on.

The thing with seeds is that they are a fairly low-cost investment, therefore a low-cost gamble, and you learn by trial and error. Here are a few basics to help you understand what is going on when you plant a seed, and why it sometimes works and sometimes fails.

water & air temperature

Inside every seed is a plant embryo. It’s like any child – it shares the traits of its parents. This is one of the reasons why saving seed is so worthwhile – we can gather them from plants that have proven to perform well in our particular conditions. For more on this, turn to page 40.

A seed also contains nutrients that feed the embryo until it grows big enough to make food through the interaction of sunlight, air and water, via photosynthesis. Seeds remain dormant until the right triggers come into play and wake them up. The aim is to break the seed coat, allowing the entry of water and oxygen. Some seeds break dormancy when they’re cold, while others like it hot. All have a favoured temperature. Beans, for example, only germinate when the ground reaches about 17°C. Where I live, in Hobart, that is usually mid-to-late spring. In the subtropics, the ground could be warm enough as early as August.

Gardeners who don’t want to wait for nature to serve up the right temperature for sowing can give their vegie or flower seeds a push along. To trick them into sprouting early, just manipulate the temperature. Seed of cold climate plants such as lavender, fuchsia and catmint benefit from chilling in the fridge, while warm season annuals can be kickstarted in winter by keeping their mix on an electric heat pad or a sunny windowsill.

Moisture is essential for the first step of the germination process. Some seeds, such as beetroot, beans and sweet peas, have a hard coating, and always germinate better after a night soaking in water. Just tip the seeds into a cup of water and strain the next day. Don’t leave it any longer as the seeds may rot.

When starting out, it’s a good idea to sow three punnets of seed. Water one three times a week,

“Seeds remain dormant until the right triggers come into play and wake them up”

medium & method

one once a day and one multiple times a day. It’s more effort and expense but it can be a valuable lesson. In many cases, after germination the frequency of watering should be gradually reduced as the seedling develops. With pumpkin seedlings, lay off the water after germination to let the soil dry out or they may rot. Lettuce, however, needs fairly constant moisture from sowing until harvest.

Following germination, the seed then needs to breathe. Oxygen allows the embryo to start feeding itself from the seed’s food stores. Light or length of day plays a part, and helps determine the best time to plant. Giant sunflowers planted too late in the season, for example, still flower but rarely get to the height and size of those sown earlier. Seeds need some kind of mix or medium for the roots to grow into. Most seeds germinate in pretty much anything, but how well they do after that depends a lot on what you planted them in.

Making your own seed-raising mix can be as simple as getting yourself a sieve, a cheap bag of potting mix, some homemade compost and a bucket. In my experience, homemade compost yields the best result by far, but store-bought will suffice. Steer clear of mushroom compost as it tends to be a bit alkaline for many plants.

My general mix is 50:50 potting mix and compost. It’s a good idea to sieve the whole lot, depending on the quality of the ingredients and the size of the seed you intend to sow and, of course, your care factor. Smaller seeds do better in a finer mix as they can be suppressed by large particles such as bark.

Mix thoroughly, lay out the mix in trays or punnets and sow your seed on top. Then sieve enough compost to cover the seeds you are sowing. If your plant needs a lighter mix that drains better, add more potting mix, and if it likes it heavier, add more compost. Seed-raising mix can be bought at your local nursery or

tricks & tips

garden centre, and is usually a good mix for raising a broad range of species. But even then, I like to throw the mix through the sieve if I am planting small seeds, such as many of the brassicas. Some seeds are heavier sleepers, and need more drastic measures. Those from bushfire-prone areas, such as Australia or South Africa, may need heat or smoke to break their dormancy, while sandpaper can be useful on hard-coated seeds, such as wattle or warragul greens, to scarify the coat and allow moisture to enter.

Many gardeners say how they love the process of sowing beans, corn and pumpkins, and I believe that is because they are not just excellent plants to grow, but also because they have large, attractive and tactile seeds. Other benefits are that they are hard to lose and not as fiddly. Small seeds are a different story, such as Iris germanica, which can be impossible to evenly distribute by hand.

Luckily, gardeners are a resourceful bunch and have developed a few techniques over the years. A folded piece of paper is invaluable when sowing tiny seeds of the cymbidium orchid in trays. Mixing your carrot seed in a jar with some washed river sand gives you more even spacing when sowing, and the sand has the added bonus of helping drainage. You can get a mechanical spreader if you are sowing a large area, such as a lawn, but I still believe a well-trained hand is one of the greatest tools for distributing seed, and there is something timeless about the action of hand-sowing a bed.

You may have heard of planting pairs or a number of seeds in one pot or hole, and this is in essence an insurance plan. As the saying goes: one for rook, one for crow, one to die and one to grow. If you do get a 100 per cent survival rate, you can leave your strongest plant and gently prick out the rest. These can often be replanted or potted up, but there are exceptions. Once germinated some plants do not appreciate interference. These include the taproot vegies, such as parsnip, beetroot and parsley. Many beans also suffer transplant shock and sulk, and some brassicas bolt and go to seed if they are moved as seedlings.

Before you know it, this season will be over, but the next one is just around the corner. Don’t regret not doing it yesterday – there is still today. Sowing a seed is putting faith in the future, and your reward is more than just a fresh, new plant.