Some weeks ago, I submitted this as an article. Having heard nothing since, I presume it was not to be. So I offer it here. I think it fits best in this forum.
The Forsyth pot has long been used to provide a constant moisture environment for rooting cuttings. The principle is simple. An unglazed clay flower pot is somewhat porous. But the pores are very small, so small that water does not flow freely through them. When there is a difference in moisture between the inside of the pot and the outside, water will flow from wet to dry.
In use, the clay pot is sunk in another planter's growing medium, up to the rim, and filled with water. When the growing medium is dry, the dry medium "pulls" water through the walls of the pot until the medium is sufficiently moist to slow and then stop the movement. When plant tissue or roots in the medium extract water, the medium dries and is replenished from the buried pot. You need only keep the pot filled.
The growing medium today is generally vermiculite, which also like to draw and hold water. The principle has spawned any number of products, like the olla, a gourd-like clay pot buried in the soil with the neck above ground for refilling, and the "watering spike," a clay spike that replaces the cap on a bottle and is stuck into the soil. In blazing hot weather, I place pots in containers that will be in the sun to help them replenish moisture between watering.
All this sounds very innovative, but the fully evolved design is 185 years old, the brainchild of the prolific British gardening professional, Alexander Forsyth. (Thus the correct spelling. It is most often misspelled Forsythe, because it was popularized around 2002, when the very popular television version of the novel, The Forsythe Saga, was being aired.)
Forsyth made many contributions to "The Gardener's Magazine." (Including "On the Culture of the Pine-apple, as practised by Mr. Dowding, at Oakhill, East Barnet."). In the 1835 Volume XI of the Magazine, Forsyth published "A new Method of striking Cuttings." In that short article, be explains his method today known by his name. Note Forsth's clever observation that placing the cuttings against the wall of the pot allows the gardener to lift the pot out and check the progress of rooting without disturbing the cutting.
The Gardener's Magazine is itself interesting as the first British periodical devoted to horticulture. The publisher, John Claudius Louden, was a remarkable man who devoted his life to the education of gardeners. The Magazine was published for nineteen years, until Louden's death. Until his last hour, he worked to encourage gardeners to improve themselves. He was a vigorous advocate of gardeners building up their libraries of references. He also published the Encyclopedia of Gardening.
He was notable for his refusal to ever again admit someone to his home who had told him a lie. On one occasion, it had become necessary to amputate his right arm. The doctors found him in his garden and asked if he was still resolved to get the operation. ' Oh, yes, certainly,' he said; 'it was for that purpose I sent for you;' and added very coolly, ' but you had better step in, and just have a little lunch first before you begin.' After lunch he walked upstairs quite composedly, talking to the doctors on general subjects. When all the ligatures were tied, and everything complete, he was about to step down stairs, as a matter of course, to go on with his business; and the doctors had great difficulty to prevail upon him to go to bed.
Included here is the image of Forsyth's original article on his rooting pot.
