Save your cardboard toilet roll holders and plastic meat trays (the latter well washed of course!) to sow your seeds. No need to transplant later- just put the whole tube in the ground and it will disintegrate as the plant grows.
I've used these tubes successfully for runner beans and sweetcorn in the past and I'm now trying out parsnip seeds in them, 3 to each tube, then I'll keep only the strongest seedling, leaving it in the tube and then planting out - still in the tube.
This was a tip recommended in a gardening magazine and, as parsnips are hard to get to germinate, I thought I'd give it a go. Nothing to see yet, but our nights are still chilly and the parsnips are in an unheated conservatory. I'll let you know what happens!
2 hours ago