* The Geography of Magic for Marigold
[top] Fan map of Harmony Harbour ©lmm-anne.net, click to enlarge.
Marigold Lesley lives at Cloud of Spruce, an ancestral home facing Harmony Harbour. Young Marigold’s world, largely composed of her own daydreams, is very insular, but there are hints of the outer world with the “spruce hill” behind the house, the dreamy harbour and the magical realm “over-the-bay.”
[left] A Google Map of New London Harbour
Harmony Harbour is described with several landmarks by “the Anglican Church over the bay”, “the dreamy [sand] dunes” with the Gulf Shore beyond, the harbour mouth which Marigold and Budge explore (ch. 21), and the “Head of the Bay,” where the Weed Man (ch.12) and some of the Lesley relatives live.
Marigold had lived her six years, knowing no world but Harmony Harbour and Cloud of Spruce…
The road outside the gate–one of the pleasant red roads of “the Island.” To Marigold, a long red road of mystery. On the right hand it ran down to the windy seafields at the harbour’s mouth and stopped there–as if, thought Marigold, the sea had bitten it off. On the left it ran through a fern valley, up to the shadowy crest of a steep hill with eager little spruce-trees running up the side of it as if trying to catch up with the big ones at the top. And over it to a new world beyond where there was a church and a school and the village of Harmony.
The harbour, with its silent mysterious ships that came and went; Marigold loved it the best of all the outward facts of her life–better, as yet, than even the wonderful green cloud of spruce on the hill eastward that gave her home its name. She loved it when it was covered with little dancing ripples like songs. She loved it when its water was smooth as blue silk; she loved it when summer showers spun shining threads of rain below its western clouds; she loved it when its lights blossomed out in the blue of summer dusks and the bell of the Anglican Church over the bay rang faint and sweet…
And she loved the purple-hooded hills that cradled it–those long dark hills that laughed to you and beckoned–but always kept some secret they would never tell… the other side of the harbour–”over the bay”–continued to hold a lure for Marigold. Everything, she felt sure, would be different over there. Even the people who lived there had a fascinating name–”over-the-bay-ers”–which when Marigold had been very young, she thought was “over-the-bears.”
Marigold had been down to the gulf shore on the other side of the dreamy dunes once, with Uncle Klon and Aunt Marigold. They had lingered there until the sunken sun had sucked all the rosy light out of the great blue bowl of the sky and twilight came down over the crash and the white turmoil of the breakers. For the tide was high and the winds were out and the sea was thundering its mighty march of victory. Marigold would have been terrified if she had not had Uncle Klon’s lean brown hand to hold. But with him to take the edge off those terrible thrills it had been all pure rapture.
Next to the harbour Marigold loved the big spruce wood on the hill–though she had been up there only twice in her life. — Magic for Marigold, ch. 3, 2
The descriptions match New London Harbour (which is also Four Winds Harbour in the Anne books and Queen’s Harbour in Jane of Lantern Hill.) Magic for Marigold was published in 1929, and this is the part of PEI that LMM knew best from her island vacations in the 1920s, split between Park Corner and Cavendish. The Anglican church over the bay is the Anglican church at Springbrook, PEI.
Montgomery would have been familiar with this vista towards the purple hills “over the bay” from the Cavendish side of the harbour. A long strip of sand-dunes run from the sand-bar on the harbour, all along the shore of what is now Green Gables National Park, turning into rock capes at the eastern end. The Gulf Shore beyond the dunes is doubtless the long Cavendish shore, lying along the Gulf of St. Lawrence.
Harmony seems to be located on the east side of the harbour, across the bay from Springbrook, not too far from the sand-dunes. In chapter 10, Princess Varvara runs away from the Summer Hotel on the Dunes - the Cavendish dunes should not be too far from Cloud of Spruce. The imaginary Harmony Village might be Bayview or Stanley Bridge.
There is a real place called “Harmony” on PEI, from which Montgomery borrowed the name, but she admits she has never visited the village.  It is located in Prince County, far away from the north shore landscape Montgomery describes again and again in all her books.
Unlike its real-life counterpart, Harmony Harbour has no sand-bar, nor lighthouse, is described, but perhaps Montgomery deleted these references in her imagination to generalize the location of Harmony Harbour. Just like Four Winds is supposedly “60 miles” away from Avonlea (Cavendish), Princess Varvara says that her relatives went to Cavendish, but she couldn’t go because there were measles there, thus displacing the location of Harmony.
Cloud of Spruce
Cloud of Spruce is a cream brick homestead, covered with vines. An orchard runs up the big spruce hill behind it, and a garden lies before it, with a white gate halfway towards the harbour (ch 3,2). There is a church barn, called the “apple barn.”(ch. 3,2) Marigold has a playhouse in a square of currant bushes. (ch.3,6) The Orchard Room of Cloud of Spruce - Old Grandmother’s bedroom - has a door that opens out to the orchard, which Marigold calls the “Magic Door,” and must pass through to see Sylvia. “The Green Gate” lies up the slope. There is a spring on the hill, which Marigold calls the “White Fountain.”
Cloud of Spruce, the original Lesley homestead, where Old Grandmother and Young Grandmother and Mrs. Leander and the baby and Salome Silversides lived, was on the harbour shore, far enough out of Harmony village to be in the real country; a cream brick house–a nice chubby old house–so covered with vines that it looked more like a heap of ivy than a house; a house that had folded its hands and said, “I will rest.” Before it was the beautiful Harmony Harbour; with its purring waves, so close that in autumnal storms the spray dashed over the very doorsteps and encrusted the windows. Behind it was an orchard that climbed the slope. And about it always the soft sighing of the big spruce wood on the hill. — Magic for Marigold, ch. 1, 1
Cloud of Spruce is imaginary. Originally called Cloud o’ Pines, perhaps Montgomery was thinking of the “hill o’ pines” she could see from the window of her Norval home. 
Spruce trees are more common than pines on PEI , so Montgomery probably altered this to be more in keeping with the Island landscape. Green Gables, New Moon, and many other farms in Montgomery’s novels all have spruce woods behind them.
 Magic Island, by Elizabeth Waterston
 Selected Journals of L. M. Montgomery v.2. Entry on favourite tree “There were few pines in Cavendish-an odd one or two back in the woods. Indeed, there are not many anywhere on the Island. It is the habitat of spruce and fir.”
Places to Visit
Green Gables National Park, which covers the long shoreline of Cavendish, including a long stretch of sand dunes along the Gulf of St. Lawrence
Stanley Bridge, possibly the area of Harmony