I have seeds for bulbing fennel, but in the past haven't had much luck in much of a bulb forming. Any advice?

You might want to check to make sure you're providing the right conditions for growing fennel from seed.  Fennel plants grow at an optimal soil temperature ranging between 15° and 18°C - which in F is about 60° and 65° and ideally plants should be grown in this temperature range. When planting the seeds in the soil, a depth of 0.6 to 1 cm or a quarter to half an inch deep per seed is ideal for optimal growth of the plant. It usually takes ten to fourteen days for the first fennel seedlings to emerge out of the ground.In the event that you've been providing these conditions and have still encountered problems, I'd suggest looking at the seeds or varieties you've been trying to plant that have not been working.