I plant mine in late september, where i want them to flower in the garden. those i grow for indoor display get planted out after they have flowered in april. hope this helps.

Although hyacinths grow well in my garden, I have never been able to transfer indoor ones to the garden successfully. May I ask are outdoor and indoor ones the same SBG?

The only difference is the way they are treated before sale. Indoor ones are pre-chilled to induce early growth and flowering. Our garden is full of the indoor ones, planted out afterwards.
You do need to get them outside as soon as they have finished flowering, removing only the old flower stem. If they have been potted in bulb fibre then that needs a real good soaking. Then plant them a good 2 to 3 inches deep (over the top of the bulb) with a little fertiliser under them. Works for us.

Thanks Owdboggy, now I know what I do wrong I have always dried them out and planted out in the autumn.

Only worth doing that if you feed, feed and feed again in the original compost.

I didnt lol