Winter Strawberries

Berryworld rents greenhouse space from the Lincoln Plant and Food site for growing foundation stock, a project which uses space from November to April…..but we pay for the space all year. Might as well grow some strawberries in the off season!

That was our thought process last February, when we set about preparing the plant material for what we hoped would be an impressive winter crop. 

First main decision: day neutral or short day varieties?

We weren’t sure what would perform best, so we chose some of both. Monterey and Valiant were our day neutrals, and Ventana, Fortuna and Victor were our short day varieties. 

Next major decision: to chill or not to chill?

We propagated all the plants in the third week of January. We chucked all the short day plants and half of the day neutrals in the chiller three weeks later. After 4 weeks chilling (4C) we took them out and let them all do their thing. It was the middle of March.

We learned several lessons the hard way. 

Our biggest lesson was that short day plants propagated in Jan/Feb and chilled until March have no flower initials. They were grown when the day lengths were telling them to make runners, and giving them chiller time didn’t change those runner initials into flower initials. Ventana, Fortuna and Victor just kept throwing runners for 6 weeks, squandering all that valuable autumn light and warmth, before they had churned through all their primordial runners and could obey the short day signal and make flowers. 

Lesson two: heat is required for Canterbury winter. 
I wanted to see what the plants could do without heat and just the natural light. Turns out, not much. See that plateau in yield–they just about stopped growing. At the end of June I had learned my lesson, and turned on both the heat (14C nights, 20C days) and the lights. On the graph the red arrow shows when the heat turned on. 

Lesson three:
We hadn’t organized for bumble bees, and pollination was inadequate in the closed up greenhouse. Next time, order bees or get a good fan going!

Lesson four: 
The short day varieties with early genetics did far better in winter production (where I wanted a quick burst of fruit) than a variety like Victor, which has done very well in summer but is not early. It was just starting to get going when we had to end the trial to make way for the next greenhouse occupants. 

Lesson five:
When using day neutrals in winter, it’s better to just start them directly after propagation, without chilling. 

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