A couple of readers wrote in about problems with their courgettes and another has lost his entire onion crop to allium leaf miner. That’s a problem that’s getting worse as time goes on.
Powdery Mildew on Courgettes
I have been growing courgettes in pots for the last few years with success but the leaves usually finish up with a white powdery dust on them. Is this a fungus and how can I stop it?
It sounds like powdery mildew which is very common on courgettes and can affect cucumbers and squashes too. There’s a diary post on this here: Cucumber Powdery Mildew, and an article on a different control method here: Biological Control for Powdery Mildew
Finally, I cover it in my book Vegetable Growing Month by Month
Hope that helps
Poor Courgette Seed Germination
Michael Ellis writes:
I have trouble germinating courgette seeds as they rarely germinate, so I buy a few plants from the local garden centre. Have you any tips about my courgette shortage i.e. lack of germination.
Usually I’ve had near 100% germination rates starting courgettes off in 3 inch pots of ordinary multi-purpose compost but this year only 50%. Then again, I only sowed 4 seeds so not a statistically relevant sample.
A couple of tips that may help solve your courgette germination problem.
First, sow the seeds on edge. The theory is that it stops water lying on the seed and causing rot. I’m not sure if it makes any great difference but it does no harm at worse.
More importantly for germinating courgette seeds is the temperature. The optimum temperature range for germinating courgettes is between 20ºC and 35ºC That’s the compost temperature, not the air temperature. See Best Temperatures for Seed Germination
If you’ve a thermostatically controlled propagator then set it around 25ºC – if not, start them off in the house. Once they show above the soil, remove from the heat. If you’ve got a greenhouse or cold frame keep in there until they’re a few inches tall and then harden off before planting out.
Allium Leaf Miner
Hi John, for the second year running I’ve lost my entire onion crop to Allium Leaf Miner. Is there anything you can suggest that will prevent this from happening again in the future? Any help or ideas would be much appreciated.
Regards Gareth Owen.
Allium leaf miner is most often a problem with leeks but it can affect any of the onion family. I wrote a full article on the problem that should help you here: Allium Leaf Miner