The end of February and the beginning of March can be brutally hot in Adelaide. But while we humans are still in full summer mode, the garden is showing signs of winding down towards autumn, with the quince trees heavy with fruit and my favourite annuals setting seed.

It may seem like stating the obvious, but the only financially viable way to fill a garden to bursting point is to start your own plants from seed. Think of Gertrude Jekyll and her 'drifts' of colour - at garden centre prices, drifts are beyond expensive.

Ordering packets of seed from specialist growers and waiting for them to arrive in the post is one of life's small pleasures, but for the thrifty gardener the real joy comes from harvesting your own seed and sowing it on in the following season.

There are a few annuals I will always want in the garden, like the chocolate scabious Black Knight in the main picture. Over the past two years they've begun to appear of their own accord, but although I love self-sown plants and almost always leave them where they choose to grow, the display is never as intense as when I go to the trouble of raising stock from seed and planting them out.

It's the same with clary sage, which is perhaps my all-time favourite of the scented herbs. Towards the end of summer, small self-sown plants begin to pop up, and as the tall flower spikes dry out I squeeze a few of their papery cups to make them spray their small, glossy, brown seeds. The rest of the seed heads are collected and stored for the future, and each autumn I sow a tray of seeds and use the new plants to fill the gaps.

I am patiently awaiting the flowering of my latest batch of seedlings. The green zinnia 'Envy' is a late summer favourite. Unfortunately, the on-line store I ordered them from seems to have disappeared, so it is more important than ever to conserve the seed.

In a busy life you need to set up a system of raising seedlings that makes it easy and time-effective, so that sowing a tray becomes a five-minute job. My own method includes a three-tier plant stand with shelves wide enough to accommodate the seed trays. I keep it close to where I store the potting mix, and the fledgling plants are all in one place for ease of watering, for pricking out and potting on. The whole stand can be moved into the shade if the weather is too hot.

In the collection department, I make sure I have bundles of blank seed packets handy. Used envelopes will also do, and it's a good second career for them. The main thing is to name and date the seed, and also to put a reminder in the diary for when you should plant it.

Allowing plants to run to seed is also a great way of diverting pests away from other plants. The adult pest will feed on the flowers and lay their eggs in the unwanted, gone-to-seed plants. Vegetables gone to seed are particularly attractive to them, and I let lovage and chard to go this way, although I've heard that dill also works well.

And finally, if you end up with too much seed for your own use, and you will, investigate local seed-swap schemes. Happy gathering!