How to sow winter onions and leeks, and sorting tomato plant problems

Sowing leeks and 'day short' onions
  • If you’re buying onion seeds you’ll need to purchase new ones every year and pop them in the fridge for at least two weeks prior to planting. When you bring them out of the fridge they’re shocked into germination by the warmth.
  • Find a tray that’s deeper than the traditional seed tray. It should be at least 10cm deep. Drill holes into the bottom.
  • You can keep a deeper tray more moist which gives the seeds a better chance of germinating. Onions and leeks also have long tap roots so they need the room.
  • Fill your tray with seed raising mix or sieved potting mix (which is cheaper if you’re sowing a lot of seeds).
  • Create rows with a piece of angle iron or dowel. Sprinkle seeds into the rows relatively thickly.
  • Label the seeds you’ve planted and don’t forget the date. If they’re not up in around three weeks’ time you know they probably won’t germinate and can start over.
  • Sprinkle a light covering of the same mix over the seeds.
  • Then it’s time to soak the tray. Fill a large bin with water to which we recommend you add around 2-3 lidfuls of liquid seaweed fertiliser.
  • Carefully lower the seed tray into the bin (the water shouldn’t cover the seed tray) and leave for about 20 minutes to completely soak the soil. When fully soaked, the soil particles expand and the soil stays moist for longer.
  • Rob puts a cake cooling rack over the seed tray and drapes a dampened tea towel (or you could use newspaper) over that to keep the seeds protected from sun, to keep the soil moist and the humidity level high to assist the germination. Place in a partly shaded area.
  • Water at least once a day and make sure you dampen the tea towel or newspaper down each day too.
  • There are two types of onions: ‘day long’ or summer varieties like Pearl Drop and Red Brunswick which grow quickly but need to be eaten immediately as they don’t store; and ‘day short’ or winter varieties like Pukekohe Long Keeper and Californian Red. ‘Day short’ varieties need to be planted while the soil is still warm, but it’s the cool weather that gets them growing to a good size.
  • Onions that are not organically grown are usually heavily sprayed during the growing period and during storage to stop sprouting, so the ones you grow organically yourself will not only taste better, they’ll be better for you too.
Problems with tomato plants
  • Green Shield Beetle is the most likely cause of damage to tomato fruit at this time of the year. With its sucking mouth parts saliva is injected into the plant and plant juices are sucked up by the beetle. It causes the tomato to rot from the inside out.
  • The damage done by Green Shield Beetle only affects the fruit and not the whole plant, so if you remove the affected fruit and the beetles, the plant will continue to produce good tomatoes.
  • The best way to control Green Shield Beetle is squishing them near the tomato plants as the smell they emit repels other beetles.
  • Other ways include planting cleome which attracts the Green Shield Beetle. When they’re all clustered on the cleome plant you can deal to them. Birds will also eat bugs and insects so install a bird bath nearby to attract the birds.
  • Excess foliage in the garden and adjacent areas provides a perfect breeding habitat for Green Shield Beetle. So keep your garden plot well-weeded early in the season before the population matures.
  • You can also get Blossom End Rot as a result of not enough calcium in your soil and not enough watering. Watering needs to be frequent and not too deep.
  • And at this time of the year it’s best to stop delateralling tomato plants as with high humidity you’d be opening the plant up to infection.


Camera: Jarod Murray
Editor: Thomas Asche
Production equipment and post-production services provided by The Black Forest Breathes