NZ Gardener - - The Good Life -


• Last sum­mer, the Auck­land Botanic Gar­dens set out to in­ves­ti­gate how best to grow toma­toes out­doors with­out blight, bugs and blos­som-end rot ru­in­ing your crop. The Botanic Gar­dens ac­tively avoid us­ing sprays so one of the aims of their trial was to find out how much (if any) chem­i­cal in­ter­ven­tion is re­quired to get a great crop in Auck­land‘s hu­mid cli­mate. • For the trial, 152 plants of 13 va­ri­eties were sown (in mid-Au­gust), grown on, and planted out (at the end of Oc­to­ber) in trial beds pre­pared with 1 cup of biofert/m². The plants were spaced 80cm apart in rows run­ning north to south, in full sun, and ex­posed to the pre­vail­ing wind. The lat­er­als were re­moved and the plants were tied to sup­port­ing trel­lis. • Some plants were sprayed weekly with liq­uid cop­per, while con­trol plants were not. However, last sum­mer wasn‘t bad for blight and only one ‘Money Maker‘ plant in the trial was af­fected, so it was im­pos­si­ble to tell if the cop­per sprays made any difference. • Is liq­uid fer­tiliser worth it? No. De­spite fort­nightly ap­pli­ca­tions of sea­weed-based liq­uid fer­tiliser dur­ing the grow­ing season, there was no no­tice­able difference to ei­ther yield or flavour. “An un­nec­es­sary ex­pense,“the trial team con­cluded.


• Of the 13 va­ri­eties cho­sen, five were cherry toma­toes, five were medium-sized and three were large meaty types.

• There wasn’t much vari­a­tion in the weight or size of the cherry va­ri­eties, re­gard­less of how they were grown, but ‘Sweet 100' and ‘Sweet Gold' pro­duced the great­est num­bers of toma­toes.

• Of the medium-fruited cul­ti­vars, ‘Juliet' had a sig­nif­i­cantly higher number of fruit but be­cause they weighed less on

av­er­age, the other cul­ti­vars pro­duced sim­i­lar yields. The in­di­vid­ual fruit of ‘Chef's Choice Orange' and ‘Early Money' were larger and heav­ier.

• Big isn’t al­ways best. Of the three large­fruited cul­ti­vars, ‘Country Taste' was the most pro­lific. The plants of ‘Beef Mae­stro' weren‘t par­tic­u­larly vig­or­ous and were first to die back (be­fore the end of the trial), caus­ing their grades to slip! Mean­while, ‘Marriage Big Brandy' didn't al­ways live up to its name, with some plants pro­duc­ing juicy big whop­pers while oth­ers yielded cherry-sized tid­dlers. • If you’re im­pa­tient, note that there was a one-month difference be­tween the ear­li­est and lat­est va­ri­eties to ripen. ‘Sweet Gold' and ‘Gold Nugget' were quick to colour up, while ‘Beef Mae­stro' and ‘Marriage Big Brandy' came in last. This isn't un­usual, as cherry toma­toes al­ways ripen first. In gen­eral, cherry va­ri­eties seem to do bet­ter than other toma­toes.


• Trans­plant seedlings on a lean. Instead of plant­ing them with their stems up­right, set them into the soil on a 45-de­gree an­gle, with half the stem be­low the soil sur­face. This en­cour­ages ex­tra aerial roots off the stem, an­chor­ing them more firmly in the soil and thus pro­vid­ing bet­ter sup­port dur­ing the grow­ing season.

• To beat blight and mildew, plant in an open, breezy spot. Re­move lower leaves in mid­sum­mer, use soaker hoses and keep the roots cool with mulch. Healthy plants are more pest- and dis­ease-resistant.

• Crop ro­ta­tion is important. If you‘ve had prob­lems be­fore, find a new spot for your toma­toes each year, or grow them in planter bags or con­tain­ers of fresh soil.

• Pos­sums a pest? Use fo­liar fish fer­tiliser. They hate the smell. It also keeps white­fly away from tun­nel­house toma­toes.

• Blos­som end rot (when a sunken patch of rot ap­pears at the base) is symp­to­matic of a cal­cium de­fi­ciency, but in­con­sis­tent wa­ter­ing is the cause, as a lack of water stops cal­cium flow­ing through the plant to the ends of the fruit. Don‘t let the soil (par­tic­u­larly in pots) dry out; daily wa­ter­ing is bet­ter than a once-weekly down­pour. Also, hose in gran­u­lar fer­tiliser thor­oughly. Blos­som end rot is more preva­lent early in the season and af­fects in­di­vid­ual fruit rather than the whole plant. Pick them off.

• The tomato/potato psyl­lid looks like a tiny ci­cada. It sucks sap and trans­mits pathogens that weaken host plants, lead­ing to yel­low fo­liage, stunted grow­ing tips and leaves that look cupped or curly. The flow­ers can drop and the fruit that fol­lows is of­ten small. Psyl­lid pop­u­la­tions peak in late sum­mer; they can knock out 7-8 gen­er­a­tions in a sin­gle season. Hang sticky traps or try neem oil as in­sec­ti­cides will also take out pol­li­nat­ing bum­ble­bees and nat­u­ral preda­tors such as hov­er­flies and steely blue la­dy­birds. Phys­i­cal bar­ri­ers work, such as a frame cov­ered in fine in­sect mesh, though you will have to hand pol­li­nate your plants once fully en­closed.

• Stinky green shield bee­tles suck beans and toma­toes dry. I‘ve learned to live with them, but if you‘ve found a cun­ning so­lu­tion, we‘d love to hear it. Email your tips to mail­box@nz­gar­dener.co.nz. ✤

Auck­land Botanic Gar­dens‘ tomato trial was co­or­di­nated by Emma Bod­ley (pic­tured) with data collection by Matthew Savage and Julie Hubrich, and sup­port from the Manukau Beau­ti­fi­ca­tion Char­i­ta­ble Trust.

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