Labour Day tomatoes? In Christchurch, give them a few more weeks

Labour Weekend, at the end of October, is the traditional day to plant tomatoes in New Zealand. It works well in Auckland and the north. In Christchurch and the rest of Canterbury it’s a gamble, because frosts can turn up until the end of October. Plant out from mid-November, or put them in at Labour Weekend and be ready to cover them.

The dates here are for Christchurch and the Canterbury Plains, with a last frost around 28 October and the first in late April.

Sowing

Sow tomato seed indoors in September, about six to eight weeks before planting out.

1. Sow seeds 0.5 cm deep in seed-raising mix.
2. Keep them warm, around 20 to 25 °C, on a heat mat or a warm windowsill.
3. Once they come up, give them as much light as you can, or they’ll stretch.
4. Pot them on into 9 cm pots when they have their first true leaves, burying the stem up to the seed leaves.

If you’d rather skip this, garden centres have good seedlings from October. Choose short, sturdy plants with dark leaves.

Planting out

Harden plants off for a week first, putting them out for longer each day.

• Greenhouse or tunnel house: from late October.
• Outdoors: from mid-November to early December. If you plant at Labour Weekend, have frost cloth or cloches ready.

Choose the sunniest, most sheltered spot you have. In Canterbury, shelter from the nor’wester matters as much as sun: hot, dry gusts snap stems and scorch leaves.

Space plants about 45 cm apart, in rows 60 cm apart. Bury the stem deep, as roots form all along it. Basil, French marigolds and carrots make good neighbours. Keep tomatoes away from potatoes, which share blight, and from sweet corn.

Staking and care

Put a stake in at planting time so you don’t damage the roots later. Tie the stem loosely as it grows.

For tall, cordon types, pinch out the side shoots that grow between the stem and the leaves every week. Bush types need no pinching.

Water deeply two or three times a week, more in a dry nor’west spell. Uneven watering causes blossom end rot. Once the first fruit sets, feed weekly with a tomato fertiliser.

Harvest

The first tomatoes ripen about 55 to 85 days after planting out, usually from January. Plants keep cropping until the cold nights of April. Before the first frost, pick any full-sized green fruit and ripen it indoors.

Common problems

Blight. Brown patches on leaves and stems in warm, humid weather. Remove affected leaves, water at the base and leave space between plants.

Psyllids. Tomato potato psyllid causes yellow, curling leaves and small fruit. Check under leaves for the tiny insects and their sugary droppings, and use insect mesh on young plants.

Wind damage. Tie in stems and add shelter.

Pick Christchurch on the tomato page for the full calendar. For raising plants from seed, when to sow tomato seeds covers the same steps.