I CHECKED IN with Richard, GROW HQ’s Head Grower about cucumbers this week to try and get some advice on how to grow them well. I find them relatively easy to grow, but the plants generally succumb after a month or so of (admittedly vigorous) cropping, and I wanted to find out why.

Richard grew cucumbers as part of his production for markets and restaurants before he joined us in GIY, so getting the most out of the plants was important to him and he’s the right guy to ask (as always).

The main issue it would seem is that I set my polytunnel up primarily for tomato growing. All the watering is done at the base of the tomato plants to get water down to the roots and to reduce humidity in the tunnel. This is done to minimise the chance of getting blight in the tunnel which thrives in humid conditions.

Maintaining humidity

The tomatoes are watered using a seep hose, which in itself is under a mypex membrane, reducing evaporation even further. These intensely dry conditions are perfect for tomatoes, and probably explain why I’ve never (touch wood) had blight on my tomatoes.

The problem is that cucumbers like exactly the opposite conditions – preferring high humidity and lots of moisture in the air. Richard’s advice is to give the cucumbers plants themselves a good damping down with water every day, particularly in hot weather.

I’ve also read that mulching around plants with straw will help maintain humidity.  Incidentally, maintaining a humid climate for them will also help prevent two other cucumber problems that have affected me in the past – the development of powdery mildew and the red spider mite.

Counterintuitive?

Knowing little about powdery mildew I would have thought this advice seems counterintuitive – that humid conditions would cause mildew – but not so. It appears as a white powdery deposit over the leaf surface and leaves become stunted and shrivel.

Red spider mites suck sap from the leaves which eventually become completely yellow and covered in fine cobwebs. The mites thrive in dry warm conditions so, again, regular watering and damping down of the plant will help.

The other piece of advice he had for me was regarding ‘side shoots’ on cucumbers. Similar to tomatoes, cucumbers develop side shoots in the joint between the leaves and the stems.

The cucumbers also develop here, so be careful not to remove the little emerging fruits.  In a similar way to tomatoes, if you allow the side shoots to develop you end up with an unfocussed and unruly plant that won’t be as productive as if you keep it well pruned.

The Basics – Tips for Conserving Water  

Generally speaking, we don’t need to water much if at all outside in the veg patch in a typical Irish summer.  But in these heatwave conditions, watering is indeed necessary and conserving water becomes a significant challenge.  Here are our top tips:

• Water properly – getting water down to the root zone takes much longer than people think. If you just water the top layer of soil, chances are it will evaporate off before it can benefit the plant. A good, heavy watering is better than an occasional light one. If in doubt, stick your finger down in to the soil to check. A heavy watering is 20 litres (or about 2 standard watering cans) per square yard.
• Water when it’s cool – either first thing in the morning or last thing at night to reduce evaporation and to get the most from your water.
• Having as much organic matter as possible in the soil will help to increase the water holding capacity of the soil.
• Keep the surface of soil around plants mulched to prevent evaporation. Mulch after watering to retain the wet conditions for longer. Mulching can reduce a plant’s water needs by up to 50%. Straw and newspaper are both good mulches.
• Get rid of weeds – weeds compete with plants for water.
• It’s too late in a dry period, but a rain butt to collect water from a shed or greenhouse roof will provide significant volumes of water for later use. They are a sinch to install, simply diverting water from the drainpipe in to the butt. It’s estimated that you could collect 24,000 litres of water a year from a standard roof.  Whether you’d need that much water is another matter.
• Drip irrigation or seep hoses are efficient and can be buried under soil to reduce evaporation.
• Focus water where it’s needed most – the leafy veg like brassicas, spinach etc; celery and celeriac; fruiting vegetables at flowering stage (but not too much when fruiting)
• Focus water when it’s most needed – typically when seedlings are young and have not developed a mature root system, right after transplanting and during flowering and fruiting.
• Reuse water used in cooking when it’s cooled down and grey water from baths, showers etc for watering plants (but don’t use water that has detergent or disinfectants in it)

Recipe of the Week – Tzatziki  

This Leyla Kazim recipe highlights the importance of getting all the moisture out of the cucumber before you start to make a perfect Tzatziki.  Otherwise the water from the cucumber will make the yoghurt thin and diluted, ruining the flavour and texture.

Ingredients  

• ½ a large cucumber
• 2 cloves of garlic
• 2 tablespoons quality extra virgin olive oil
• 1 x 500g tub of strained Greek yoghurt
• 1 small bunch of fresh dill
• a few sprigs of fresh mint
• 1 lemon

Directions  

Slice the cucumber in half lengthways and cut or scrape out the seeds – this is where most of the water content is. Grate the remaining cucumber.

Place the grated cucumber in a sieve, rest it on a bowl and add some sea salt. Give it a stir, and leave to drain for a few hours, or overnight in the fridge. Stir now and again, helping it along by pushing the liquid out with a spoon.

In the meantime, peel and finely grate or crush the garlic, then combine with the oil in a large bowl. You can allow this to sit for a few hours to mellow out the pungency, but it’s not essential. When most of the liquid has drained from the grated cucumber, spread it out over a tea towel and pat dry.

Combine with the garlic mixture, then stir through the yoghurt until evenly distributed. Finely chop the dill and mint leaves, then fold through the yoghurt mixture along with a squeeze of lemon juice. Season with salt to taste. Serve with warm pita or alongside salad and grilled meats.  

Michael Kelly is founder of GIY and GROW HQ. 

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