The sweet taste of out-of-sea­son straw­ber­ries

Plant­ing dates could be var­ied early re­sults of Palmer­ston North tri­als are show­ing.

NZ Grower - - The Final Word -

The nor­mal method of grow­ing straw­ber­ries in New Zealand is to ob­tain run­ners in May from one of the spe­cial­ist straw­berry run­ner pro­duc­ers, and to plant them in the field into a raised bed cov­ered with a black poly­thene mulch.

The re­sult is that ripe fruit, depend­ing on the dis­trict, will be­come avail­able from Oc­to­ber through to Christ­mas for short day va­ri­eties, with the pos­si­bil­ity of a se­cond crop in the au­tumn. The day-neu­tral va­ri­eties will ac­tu­ally crop con­tin­u­ously through­out the sum­mer.

In re­cent years the pro­duc­tion of straw­ber­ries in green­houses, usu­ally high plas­tic clad tun­nels, hy­dro­pon­ics, and ta­ble-top grow­ing sys­tems, has sig­nif­i­cantly changed the way in which straw­ber­ries are grown. It’s sig­nif­i­cantly in­creased yield and qual­ity and also ex­tended the har­vest pe­riod, by weather proof­ing, to some ex­tent, the pro­duc­tion sys­tem.

This de­vel­op­ment has not, how­ever, con­sid­ered whether the plant­ing date of the young run­ners should, or could, be mod­i­fied, and what ef­fect such changes might have on yield and har­vest time.

Over the past few years my former col­league Damian Dug­gan-Jones and I have un­der­taken a pre­lim­i­nary study to ex­am­ine the ef­fect of plant­ing date on the pro­duc­tiv­ity of green­house straw­ber­ries. The re­sults clearly demon­strate that even in Palmer­ston North, which could never claim to have good win­ter light con­di­tions for green­house crops, that ripe straw­ber­ries can be pro­duced at any time of the year. More de­tails of this study will be pre­sented in a fu­ture ar­ti­cle.

My in­ter­est in out-of-sea­son straw­berry pro­duc­tion be­gan in my early teens, when I at­tempted, un­suc­cess­fully, to

Lo­cally grown, freshly har­vested fruit should cer­tainly ex­pect a pre­mium over tired im­ported pro­duce

grow pots of straw­ber­ries on the kitchen win­dow of my par­ents’ home in Eng­land. This was stim­u­lated by a book on com­mer­cial berry fruit pro­duc­tion by Charles Old­ham, ar­ti­cles which my grand­fa­ther had saved from gar­den mag­a­zines on pro­duc­ing out of sea­son fruit in green­houses in the walled gar­dens of stately homes and I am sure the im­pact of the out­stand­ing ex­hibit of pots of straw­ber­ries at the world renowned Chelsea Flower Show by Water­perry Hor­ti­cul­tural School near Ox­ford which reg­u­larly was awarded a Gold Medal-the shows top award.

Sixty years later I su­per­vised a stu­dent’s hy­dro­pon­ics green­house study of straw­berry pro­duc­tion, and this re-ig­nited my in­ter­est in the crop. This re­sulted in my vis­it­ing Bel­gium, where year-round straw­berry pro­duc­tion is a well es­tab­lished in­dus­try, and un­der­tak­ing a se­ries of green­house ex­per­i­ments look­ing at such as­pects as va­ri­eties, plant den­sity, grow­ing medium and more re­cently plant­ing date.

The first ques­tion to an­swer is there any de­mand for out of sea­son straw­ber­ries?

Cer­tainly the de­mand (cur­rently?) is not as high as in the sum­mer, but im­porters still find it worth-while to bring in prod­uct from Aus­tralia and United States even though it has to be treated against fruit fly, and is sev­eral days old from har­vest be­fore it reaches the su­per­mar­ket shelf. Lo­cally grown, freshly har­vested fruit should cer­tainly ex­pect a pre­mium over tired im­ported pro­duce

The yields which we achieved are prob­a­bly much lower than might be achieved, be­cause all plants re­ceived ex­actly the same wa­ter­ing and fer­tiliser regimes ir­re­spec­tive of plant­ing date or va­ri­ety - although of course less fre­quently in the win­ter. This meant that the less vig­or­ous va­ri­eties tended to be over­wa­tered, as did the newer plant­ings.

An­other pos­si­ble in­crease in pro­duc­tiv­ity dur­ing the win­ter would cer­tainly be achieved by us­ing sup­ple­men­tary light­ing, both to in­crease the length of day for pho­to­syn­the­sis, and pos­si­bly pro­vide ad­di­tional light dur­ing the day on dull days. High Pres­sure Sodium (HPS) lights would be one op­tion, but even­tu­ally (in­evitably) LED’s will take up this im­por­tant role.

One of the big at­trac­tions of New Zealand’s hor­ti­cul­ture to me is that it is a very dy­namic in­dus­try, very will­ing to look at new in­no­va­tion.

▴ Green­house straw­ber­ries in Bel­gium in May.

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