Some time ago, on this forum, I asked for a source of "Long Tom" square plastic pots as I had admired the seried rows of such pots on Ian Young's Bulb Log. Maggi replied with a link to Orchid Supplies Ltd (orchidsupplies.co.uk) and I have bought from them several times now. Look under pots - cymbidium - black. They come in two sizes - I buy the larger size as I grow Narcissus, some Tulips and Fritillaria, all of which seem to like deep planting.
I'm posting this as I've been very pleased with the helpful service I have received from Orchid Supplies and thought a refresher posting might be useful to new members. Also, the seed exchanges will be upon us soon.
Jack