Medwyn Williams applies some science to leek growing!
I’ve set up a laboratory to find out why my blanch leeks are yellowing at the tips
This year I’m trying to get to grips with electrical conductivity (EC), because my blanch leeks are yellowing and dying back at the tips of the leaves. Apparently, it can make a big difference to your plants if you know the EC of your soil.
EC is the measure of total dissolved salts in a solution and this influences a plant’s ability to absorb water. The higher the EC, the more nutrients are available to the plants. But it’s not that easy, as too high an EC can be detrimental to soil and plants.
I decided to check up on the pH of the soil as well as the EC level in the beds where my leeks are growing. To do this, I took eight small soil samples along the bed using a tablespoon, going down to where the roots were. I mixed the samples with deionised water, let the samples settle, filtered them, then took the readings.
I have an accurate pH meter as well as an EC meter. According to the charts, the pH for leeks should be between 6.8 and 7.2 and I was pleased to see that the pH in the bed was 7.0, which is where I like it to be. The EC was 0.8, which is a bit on the low side.
I gave the leeks a liquid feed of Canna Coco A and B to provide all the nutrient elements they require. This raised the soil’s EC level to 1.6. After four days, I tested it again and the EC had gone down, suggesting that the leeks were taking in this additional feed. The nutrients have to travel from the feeding root tips to the tips of the flags – which is at least 2.1m (7ft) – so it’s no wonder they’re yellowing at the tips!