Steve's Leaves

As chat up lines go, declaring ‘I grow watercress’ seems destined to fail. But such is the passion of Steve Rothwell, a salad leaf guru, that he won over the heart of his wife-to-be.  

I recently met Steve over a slap-up dinner. He’s head scientific honcho for the largest baby salad leaf grower in Europe. So he has plenty of expert horticultural advice for all of us growing our own. 

As Steve makes clear, supermarket salad bags – those puffy plastic pillows – are big business. Vitacress Salads Ltd supplies around 1.5 million bags each week, with an annual turnover of more than £100 million.  

 “It’s a hell of a science,” explains Steve, who lets me into his secrets. Teams of researchers perfect growing techniques; workers mow vast fields of miniature leaves.  

He’s frustrated that most end up in supermarket own-brands, lost in a “hedge” of similar products. So he’s launched ‘Steve’s Leaves’, his own independent brand, showcasing unusual varieties such as a spicy wild red rocket.  

His first tip? It’s all about the wind. His leaves are grown outdoors, not in polytunnels or under glass. This produces sturdier leaves with superior texture and flavour.  

If you’re growing indoors, for example on a windowsill, the air barely moves. Plants may look healthy, but are flimsy. They develop “big puffy cells, quite weak structured,” says Steve. 

Indoors, there is less ‘translocation’, when the movement of air promotes the evaporation of water from the plant leaves, which then triggers the drawing of more water and nutrients up through the plant tissue.  

Outdoor plants, toughened by the wind, develop smaller cells. (A special enzyme is responsible – more later). It’s like building a wall from stronger, smaller bricks rather than breeze blocks. 

This principle is all important in gardening. Many of us are starting off seedlings indoors before planting outside. At this stage, mimic the action of the wind. Brush plants gently with your hands, whenever you can. 

Flimsy plants then suffer shock if they go straight outdoors. So ‘hardening off’ is the next process. Give them a period of gentle and gradual transition.  

There are various approaches: for a couple of weeks, move them outside during the day, then back indoors at night, taking care of extremes of weather.  

Or give them a stint in a sheltered spot such as under a cloche (a protective covering such as horticultural fleece) or in a cold frame. 

In case you wondered, Steve divulges that the special enzyme that toughens plants is called Xyloglucan Endotransglycosylase. It’s a bit a tongue twister - not recommended for romantic conversations.  

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