Beginner's guide to vege gardens: The argument for seeds vs seedlings
In part three of our "Start a Garden" series, we are looking at starting from seed versus buying seedlings. If you are looking at it from an economic point of view, then there's not really an argument. A packet of hundreds of lettuce seeds can be half the price of a punnet of six lettuce seedlings so it's far, far cheaper to sow your own if you want to grow your own! Plus only a very few vege varieties are actually available as commercial seedlings, so starting from seed means you can pick from hundreds of heirloom and hybrid varieties available as seed.
But, as gardeners know, money isn't everything! If you have a small garden and only plan to grow a couple of tomatoes, then it doesn't make sense to sow a hundred plants. Punnets might be easier and more convenient for you. Plus there are some crops which are both relatively slow to start from seed and which you don't need a lot of at any one time where it might be easier to plant seedlings – let's face it, who needs more than half a dozen cabbages or caulis ready to eat at once!
There are some plants however that should always be started from seed. Plants with a taproot, like coriander, dill or fennel, are always best sown direct as they resent being transplanted and are likely to bolt straight to seed if that delicate tap-root is disturbed. All root crops such as carrots, beetroot and radishes are also best sown direct. Before you point out that you see punnets of seedlings of these for sale at the garden centre, don't be fooled! All of these edible crops are best sown direct, or started from seed in the spot where you want them to grow.
Whether you are sowing from seed or starting with seedlings, it's a good idea to practise a successive planting regime, where you sow or plant a little bit every week or two rather than getting over-excited on the first fine spring weekend and planting a hundred lettuces at once. You want to end up with a long cropping period rather than a sudden overabundance of any one edible crop. Plus this way you'll have new plants coming on if something goes wrong with your first attempt.
Obviously sowing seed only makes sense if the seed actually grows! Success with seeds is relatively straightforward – every seed wants to grow, after all – but there is a bit of basic equipment that will help improve your strike rate. To begin with use fresh seed. There should be an expiry date on the packet, check that before you buy. (You can sow seeds that have passed their best-by date, but germination rates may be lower.) And seed-raising mix is worth every cent. It should contain fertilizer suitable for baby plants, water-retaining agents to hold water near their roots and a fungicide to prevent damping off plus the soil particles in it are small so the new roots can push through. Don't fill up seed trays with garden soil – it can contain weed seeds and soil bugs – or potting mix, which is too large and gritty for small seeds.
You can buy inexpensive black seed-raising trays at the garden centre, or sow into recycled plant punnets and individual pottles. A mistake new gardeners often make is sowing seed too deep. Seeds only need to be lightly covered with soil, and small seedlings will struggle to reach the surface if sown too deeply. In general, sow no deeper than twice the size of the seed.
Seeds need heat and moisture to break dormancy. Different crops require the soil to be a certain temperature in order to germinate and won't strike if it's below that, but you can use cloches, bell jars and cold frames to cheat the seasons and warm the soil up a little so you can raise seedlings outside.
Too much water is as problematic as too little with seedlings. In soaking wet seed-raising mix, seedlings risk being knocked off by the fungal disease 'damping off' (they will look fuzzy and mouldy, then fall over). Just mist with water so the seed-raising mix is moist rather than wringing wet and never leave them sitting in water.
Tomorrow look out for part four in this start a garden series: pots and small spaces.
This is part three of an eight part series on starting a vege garden. If you want ongoing tips on what to do in the garden each week, sign up for free to NZ Gardener's online magazine Get Growing and get this info delivered to your inbox every Friday.
- NZ Gardener