What is a hothouse?
	"The object or end of hot-houses is to form habitations for vegetables, and either for such exotic plants as will not grow in the  open air of the country where the structure is to be erected, or for such indigenous or acclimated plants as it is desired to force or excite into a state of vegetation, or accelerate in their progress to maturity, at extraordinary seasons."(Robert B.Leuchars, 1851: 25). Any large estate would have required a hothouse, or artificially-heated greenhouse, to provide shelter for exotic plants in the winter and for propagation all year round. A hothouse differs from a greenhouse in the fact that it is artificially-heated, by a fireplace, for example. The more delicate plants and shrubs would be brought to the hothouse from the main house with the onset of cold weather for maintenance and propagation.

	The Hothouse at Mount Uniacke
	As Found
	A deep foundation measuring twelve by six meters was traditionally thought to be the location of the hothouse. According to the original museum caretaker  the foundation was "pretty well filled in and grassed over when he came, so he dug it out to the extent that exists today". The foundation is located approximately one hundred and sixty meters north of the main house, halfway up a moderate slope. Before the 1992 excavations it was about sixty centimeters high and forty centimeters thick with two "planting beds" in the centre and a deep hole at the east end. Very few artifacts were observed on the surface.

	As Documented
	The single piece of documentary evidence attesting to the existence of a hothouse as an original estate feature is the probated will of Richard John Uniacke, where all of the estate buildings and their contents are listed. The probate was carried out by Uniacke’s sons on November 17 and 18, 1830, and is invaluable because it lists all of the buildings on the estate in 1830, the only evidence of the original estate lay-out. The last major building inventoried was the "Upper Hot House", although its exact location was not given. A map of around 1820 shows a building of the same orientation in the same location. Richard John Uniacke's design for his estate was derived from the resources of his own library. Among the most influential references was Phillip Miller's The Gardener's and Botanist's Dictionary, published in 1807. This text was especially useful in interpreting the design of the hothouse. A second text of Uniacke's is Thomas Mawe's Every Man his own Gardener, published in 1782. Both of these texts were invaluable in interpreting the data gathered from the excavations. See their full citations on the Important Sources page.

	The 1830 probate inventory lists all of the plants in the hothouse when Uniacke died in 1830. These are summarised in the probate. There are fifteen varieties of plants and shrubs listed in the inventory, twelve of which are identifiable. The most numerous is the geranium, of which eighty-one pots are listed. These would have been over-wintered in the hothouse, then in the summer transplanted to the gardens and moved into the main house where they would have been a dominant presence. The second most numerous plant was the myrtle consisting of two pots, three tubs, and eight boxes. The preponderance of tubs and boxes suggests it was used in an exterior setting around the house in the summer.

	As Excavated
	The primary objectives of the 1992 archaeological investigation of the hothouse were to confirm its function and establish, if possible, construction and abandonment dates. A secondary objective was to encourage visitors to explore the site and to see the estate in a much broader context. The 1992 archaeology confirmed the site to be that of the "Upper Hot House" and indicated that it was an original feature of the estate operating up to, but not long after, Uniacke's death in 1830. There is some question as to whether the direct descendants of Uniacke possessed the means and/or desire to maintain the estate in full, and the hothouse may have been forsaken as an unnecessary expense.

	Prior to the 1992 archaeology, the exposed foundation was thought to represent the complete hothouse structure; however, as the excavation progressed and historical sources were consulted, it was increasingly clear that the building was much larger than anticipated. The excavations also showed that the hothouse consisted of two distinct areas under a single roof: a shed/utility area along the west and north; and a hothouse area along the southeast. The southwest corner was uncovered, but the search for the northwest corner proved futile. It was discovered, however, that the northwest corner ran at least three meters further west than the southwest corner. This overlap likely delineates the shed/utility area. Other structural elements uncovered during the hothouse excavation were walls, floors and a fireplace.

	A three by three meter pit in the southeast corner is probably a tan or bark bed used to force young plants and to protect exotic species during the winter. It would have been filled with pine bark, or similar material, which, as it composts, gives off a great deal of heat. The pots containing the plants would have been plunged into the bark for warmth. The location of the pit fits well with Miller's hothouse design: "The wing facing the southeast should always be preferred for the warmest or bark stove, because the sun, at its first appearance in the morning, shines directly upon the glassed, and warming the air of the house, gives new life to the plants, after the long winter season."

	As Interpreted
	It probably looked very much like the one excavated by Beaudet in Québec City shown in the 1818 illustration on the right. The main purpose of the Uniacke hothouse was most likely to start plants early in the season and to store the more delicate plants during the winter. It is also possible that Uniacke was experimenting with horticulture, as he was doing with agriculture, and used the hothouse as a centre for this activity. The Uniacke hothouse was a surprisingly large one containing a wide variety of plants and shrubs, just a one would expect on a country estate in England or Ireland, and reflecting Uniacke's keen interest in all things horticultural. The hothouse features a tool shed and a bark bed. The bark bed is a deep hole which would have been filled with tree bark. As the bark composted it gave off heat. Plants were plunged into this bed for protection and propagation. Apart from its practical function, the hothouse may have also served an aesthetic function as an element in the vista from the main house, its location being part of the original design concept.

	Layout
	The archaeology showed that the hothouse consists of two distinct areas. This division is also suggested in the 1830 probate by separate listings for the tools and plants. One would probably enter through a door at the southwest corner into a shed, possibly a lean-to structure attached to the hothouse. This area held the tools and equipment necessary for operating the hothouse as well as the maintaining the gardens and orchards. The fireplace and fuel supply would also have been in this section. To the south of the fireplace was the entrance into the hothouse section of the structure. The shed area may have only had a dirt floor, but the hothouse would have had a wooden floor where the plants were kept.

	Orientation and Location
	The hothouse fronted on the south, halfway up a south-facing hill, an orientation which would expose the greatest surface area to the sun. The location, however, according to Leuchars, is less than desirable: "A bleak, elevated position should never be chosen, if there be any choice left" (1851: 14). The choice of such a site was likely dictated by a combination of three factors: there was no other site available; the site was chosen for its view or to be part of the vista from the house; or, it was close to a water supply. A well was found near the hothouse, but it is likely that the hothouse was designed to be part of the vista as well.

	Light
	One of the most important elements for the propogation of plants is light. The Uniacke hothouse would have been designed to let in as much sunlight as possible and may have resembled the 1815 greenhouse excavated by Beaudet on the Terrace in Quebec City. The style is a span-roof with a front wall of glass and a partially glassed roof. The second style of hothouse resembled a lean-to and had a glass wall sloped at 45° and running from the floor to the ceiling. Miller preferred the span roof style for its more efficient distribution of light. A great quantity of glass was recovered from the Uniacke hothouse, however there is insufficient data to determine whether it is from the structure itself or the glass hotbed frames which the probate indicates were stored in the hothouse.

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