successful seed sowing in pots

The transformation of a seed to a plant is a true wonder of nature. It’s still early to sow seeds but if we have some mild weather in next few weeks, getting them in early will pay dividends. I’ve sown turnips, carrots, beetroot, rocket (arugula) and radishes under a cloche and under frostcloth outside this week. In pots in the tunnel house I’ve sown broccoli, lettuce, silverbeet, pak choi, cabbage, onions and leeks. A sunny windowsill will work well too. I’ve also sown some peas in old pieces of spouting (guttering) – 20 seeds in two off-set rows in a piece a meter long. Peas don’t like being transplanted so the theory is that this minimises root disturbance – you dig a trench the size of the spouting and slide the peas in. I suspect it may prove more difficult than it sounds, but my peas were decimated by birds and mice last year, so it’s worth a try.

The fresh food garden course includes more information about sowing seeds and a chance to try your own on the day. There are places available in October (4th, 19th and 27th) and November (29th).

Here are some tips if you want to start some seeds of your own in pots.

Sowing in pots enables you to sow earlier in the season than outside. Some plants don’t like to be moved so you have to sow them direct, particularly root vegetables. Sowing in pots involves more work, but you’re likely to get a greater success rate as the seeds get more attention and protection when they are at their most vulnerable. If you’re short of space you can have seedlings waiting in pots when a space comes free in the garden.

If you don’t have the time or inclination to grow vegetables from seed, there’s nothing wrong with buying seedlings, although the varieties available in New Zealand can be limited. Buy from somewhere they are well cared for.

1. give them a good start with good potting mix

The potting mix provides the seedling with nutrients and water. Most mixes allow good drainage and are sterilised so you won’t get any weeds. I don’t usually bother buying seed raising mix although some potting mixes are too lumpy and you’ll need a fine one for seed raising. Certified organic potting mix can be difficult to find – some is labelled ‘organic’ but this just means it comes from organic matter (usually bark-based) which is the case for all mixes.

2. choose your pot

You’ll need a pot that will be big enough to allow your seedlings roots to grow as long as you plan to keep it before planting out. I sow two or three seeds in a pot for each seedling I need and pull out the extra ones if they all emerge. I use ten cm square pots or small ‘modules’ (four or six pots joined together). I don’t use seed trays as I don’t like all the disturbance to the seedling roots when you try to separate the seedlings to plant them out.

You can make your own pots from yoghurt cartons with holes punched in the bottom for drainage. Another alternative is to sow lots of seeds and then ‘prick’ them out into bigger pots. I think this just adds work and disturbs the seedlings unnecessarily, unless you need a vast number of seedlings. You’re better to sow four lettuces this week and another four next week than to have eight all ready all at the same time.

3. water, sow, water

Fill your pots with potting mix, tap them to settle the mix and water with a fine spray. Make a small depression in the centre (about 5mm deep) with your finger and sow two or three seeds for small seeds. The depression gives the seed its own mini micro-climate. It also ensures the water flows towards the seed and makes it less likely that the seed washes away.

For larger seeds (cucumbers, melons, zucchinis) I just use one seed per pot and press them into the soil about the depth of the width of the seed.

For small seeds I don’t cover them with soil. I water them after sowing using a hand-sprayer to give a fine mist. Unless you find a watering can with a very fine rose (which I haven’t yet in New Zealand), a watering can will deliver too much water and may wash your seeds away. Once they are up and established you can use a watering can safely.

4. label your pots

Always label your seeds with the variety and date of sowing. If you’re sowing lots of seeds, get into a routine of always labelling your pot at the same stage in the process, for example after you sow. Some seeds are difficult to see and you’ll find you’ll forget what and whether you’ve sown and end up with empty pots or ones with twice as many seeds as you needed.

5. keep them moist and at the right temperature

You’ll need to check your seeds daily to ensure they don’t dry out. Keep them at an even temperature if possible. Kings Seeds catalogue this year gives some great information about preferred germination temperatures. Once the seedlings emerge, choose the healthiest seedling and pinch off the others so you don’t disturb the roots of the one you’re keeping.

Watch out for slugs and snails if your seedlings are outside. Birds and mice can eat seeds too. Fresh seed germinates best but if you look after your seed you’ll find it will last two or three seasons at least. Once you see roots poking through the bottom of the pots it’s time to plant the seedlings out or move them into a bigger pot.