Grow your own tomatoes

Tomatoes are New Zealand’s favourite homegrown crop, and no wonder. Fresh, perfectly ripe tomatoes are a taste sensation, sliced on buttered white bread with salt and pepper, or mixed with fresh basil and mozzarella into a salad; plus they can be bottled, dried, frozen and preserved as pasta sauces, soups or relish.

GET STARTED

You can plant tomato seedlings from late October until January in warmer regions, and November and December in cooler regions. Don’t be in a rush to get plants in the ground, especially in cooler regions; with this crop steady warmth is key to strong early growth. Wait until Labour Day or early November if there’s a chance of a late cold spell. Late-planted toms will soon catch up with, and even overtake, earlier plantings that will be sulking after a cold start.

STEP BY STEP

Plant tomato seed about 5mm deep in trays or jiffy pots of moist seed-raising mix. Seed should germinate in five to 10 days. Once sprouted, move the seedlings into diffused but strong sunlight (not too hot and not too suddenly – young tender seedlings can get sunburn). Once plants have two or more true leaves, pot on into individual pots filled with a good quality potting mix. You can use small plastic or terracotta pots, but if you don’t have enough spare there are plenty of easy DIY options – make your own newspaper pots or use rinsed out disposable coffee cups. The spacing of tomato plants varies between varieties, but most need to be spaced at least 50cm apart in the garden and leave about 60-100cm between the rows. Cherry tomatoes – while they have smaller fruit – need just as much space as large-fruiting sorts (if not more, because they sprawl).

In regions with humid summers, where fungal diseases thrive, reduce the risk by spacing plants further apart to ensure better air circulation. Tomatoes can grow roots all along the stem so plant deeply, so the soil line is just below the first set of leaves, and they will develop a bigger root system, which will support a more robust plant.

You can also dig a trench and lay the plant horizontally on top and then bury it up to the first leaves (it looks odd, but don’t worry the plants will quickly turn upright again). Tomatoes can get (very) tall and some bear heavy fruit so most varieties appreciate support. Stake at planting time and tie the main stem to the support, especially if you are in a windy or exposed spot.

Tomatoes do very well in pots but use a high quality potting mix which contains slow release fertiliser and a wetting agent, and be prepared to water every day.

GROWING TIPS

Tomatoes are gross feeders and appreciate a rich soil. Prepare the spot where you plan to plant them with compost, sheep pellets and a tomato fertiliser prior to planting. There are all sorts of tips on what you can add to the planting hole to ensure tomato success; from a handful of milk powder or eggshells, based on the theory that calcium deficiency is one of the causes of blossom end rot; a spoonful of molasses to boost earthworm and soil microbial activity; Epsom salts to prevent a sulphur or magnesium deficiency; or flowers of sulphur said to reduce the risk of blight. Side dress with compost again in January as fruit production starts to ramp up.

Give tomatoes a spot in the garden that offers them at least six hours of sun a day, and up to eight if possible (more sun actually improves the taste of toms, since it’s sunlight that lets plants photosynthesise and make the carbohydrates – sugars, acids and so on – which give tomatoes flavour). Look for a spot at the base of a brick or concrete wall that can act as a heat sink on sunny days, especially in regions with cool summers.

Good drainage will also prevent all sorts of problems in the future, as poor drainage causes or contributes to bacterial wilt and will exacerbate the impact of inconsistent watering (which is what causes blossom end rot and splitting or rotting fruit). If your drainage is poor, consider growing only in pots.

But the most important thing, by far, is to give tomatoes a site with good air circulation and avoid overcrowding. It’s always tempting to try and cram in more plants, but too closely planted tomatoes are more susceptible to the various fungal infections to which tomatoes are already so prone.