As a member of the onion family it's curious that the leek is grown at almost the opposite end of the year to its bulbous cousin. Though this fundamental difference may seem a barrier between their similarities, they are in fact very akin.
From a physical point of view, leek seeds are as petite as onion seed and although they can be direct sown, I germinate them into trays. Leek seedlings come up in fine wisps like grass plants and are a very delicate green. Once the seed has germinated and sprouted, pot them on into larger containers. This gives the leeks a head start and by the time they go into the ground the plants should be quite stout, upright shoots around 200mm tall.
Opinions on the best time to plant leeks vary from gardener to gardener. Some insist if you want some big green fatties for winter, they must go in during early summer. Other gardeners plant all year round except for winter. For what it's worth, in theory I concur with the former, however in reality I practice the latter. Perhaps next year I will work by a new rule - onions out, leeks in. I would germinate my seedlings around October and treat leeks as an allium (which it is) or root crop and plant them after fruits - a good spot might be where your tomatoes were. This year I'm having a go at mini-leeks, although you don't need to let your leek reach full size to get the benefits. Small, early leeks are still beautiful and sweet. Here's how to grow perfect leeks:
Raise a soil ridge 200mm high along the length of the bed.
Cut a 200mm channel, or furrow, through the middle of the ridge. Dress the furrow with compost and water.
Plant the leeks into the bottom of the furrow just covering the roots, about 150mm apart.
As the plants grow, fill in the furrow around the leeks' trunks. This blanches the trunks keeping the leeks soft and white.
Mulch and water well and dress once or twice with blood and bone.
Leeks do quite well in heavy soils and will actually respond positively to clay loam. I'm not talking about full on "let's make a pot" clay, more a reasonable loam with a significant clay proportion.
The key thing is to keep your leeks well watered and to mound around the trunk to produce the softest flesh.
3 of the best: double banger flowers
1. Vireya rhododendron
When the season goes your way, be prepared for a late summer colour explosion.
I always put these in twice. Once in spring to welcome in the sunshine and again in late summer to say my good-byes.
Dead-head lavender after its first flowering to enjoy a second bite of the cherry.