why are my leeks so small??

Much the same as MF.

However some gardeners, novice or experienced have different procedures to planting. Whatever method or under whatever conditions the seed is sown really has little influence.

Come planting out time. Well dug over area, light treading down of the soil to firm. Then using a dibber, make good straight holes. Water and let soak away, then drop the young plant down the hole. It's upto you if you then fill the hole with water. I prefer not to.

Some gardeners tend to plant out in a similar fashion to normal planting, dig hole, insert plant , fill in and firm. With leeks. Don't fill in and firm. The hole made by the dibber has actually formed a growing area like a tube. As will all plants. They grow towards the light. A similar example on the plot or veg garden is rhubbard. To force the latter, it is usual to place say an old bottomless dustbin etc over the crown. The emerging growth rapidly races toward the light.

Back to the leeks. Here the plant depends much upon soil temperatures. Recently, it can't go without notice. We have had scorching hot days and way out of season very cold days, dry spells and flood spells. Now a test. You may find that your smaller leeks actually have more flavour.