If you are interested in supplying could you please read the specifications section regarding the materials you produce, these would be the minimum requirements of most thatchers.

Any materials would have to be dry and free of mould, disease, fertiliser outside the specification or pollutants  and securely fastened to retain shape. There is a demand for high quality material but standards are high.  - Advice is free -  

Straw specially selected and managed in the field, Cut with a binder and thrashed in a thrashing drum, the straw is then drawn by hand into tile like bundles called yealms. These are usually fastened on the old coat with spars after stripping off superfluous and decayed materials. Normally strips called stelches are built up from the eave to the ridge. The method is very labour intensive but is commonly seen this will retain the "tea cosy" look and historic ceilings and timbers are rarely affected. The disadvantage is the relatively short life (25 years #) and the reliance of this method on the fastening methods used on the base coat fastened into, which was normally grass rope.

Combed Wheat Reed (Devon Reed)

This is prepared initially in the same way as long straw but at the thrashing stage the drum is fitted with a comber attachment which holds the sheaf of straw throughout the operation so that the straw reappears as a sheaf with the leaf and grain stripped out. Apart from the fact that the roof is usually sheared to a close finish and thatching is horizontal in courses the fixing methods are similar to long straw. In appearance the finish is a halfway house between long straw and Norfolk reed and a life of (40 years #) is expected. This method is probably the oldest straw roof as before the thrashing drum appeared the sheaf would be flailed and then used to thatch as we do now with combed reed

Norfolk Reed (Water Reed, Marsh Reed, Continental Reed)  Link to Husbandry

This material has come to dominate thatching in recent years due mainly to the long life (75 years #) and the fact that it is less labour intensive and quicker to learn for the thatcher. The reed in the bed or rond is a naturally occurring stage of the land encroaching on the marsh, but to develop good reed needs skilled management of the water level and top hamper of dead material. It is cut and used without any thrashing, with an Allen scythe adapted for the purpose, or with a rice harvester as conditions are equivalent to a paddy field for most of the cutting season which is winter time. Fixing to the roof is normally by a steel hook driven into the rafter holding the reed under tension by use of a horizontal sway, It used to be tied with tar cord. Again water reed thatching is a very old method and not restricted to the Norfolk Broads but used wherever reed could be found. Reed used to be far more common than is appreciated, with monastery fish ponds and tracts of marsh land abounding,

Sedge (Water Grass)    External Link to Wicken Fen For description of growth & harvest

Can be used as long straw but more often used as a ridging medium for Water Reed. Cultivation, cutting and habitat basically the same as reed; cut in Summer.

# Approximate only, many variables can affect the life.

These notes are not intended to be definitive, merely 40 years observation