Rosebay Index
Rosebay Index

The Rosebay Volume 3 Number 1 Winter 1974

Nantucket, Mass

Growing Rhododendron From Seed By Jonathan Shaw
Editors' Notes
Sunset Reprint (Speedup for Rhododendrons)
A Visit with...
Chapter Notes
Heritage Plantation Survey
News Items
Impending Publications
New Members


By Jonathan Shaw

A recent article in the October 1973 issue of "The Quarterly Bulletin of the ARS," concerning a modern method of growing Rhododendron from seed was of especial interest to me, as I, too, have been growing such seed for the past six or seven years. While I cannot claim any innovations in the germination of seed, I thought it might be of interest to record my own method. I believe I have found a simple, useful method of growing on seedlings from the first transplanting.

Seeds: I suggest that you use seed from your own crosses. Experience reveals that such seed has greater vigor. I commence my seed January 1, (or even as early as October 1) hence the seed is fresher. Perhaps that is the reason seed that arrives from the ARS. Seed Exchange in March or April, in my hands, germinates less well. In addition, I prefer to sow a greater amount of a cross than is available in a packet received from the Exchange.

I recommend two or three hundred seeds as a minimum. Perhaps a third of these will not germinate at all or will be weak, small seeds that will not transplant successfully. Perhaps another third will die during the first winter outdoors. Others will succumb in later years. The result may be that fifty or less plants will be brought to blooming age. The January 1 date is a good one in that it allows plenty of time for growing to a reasonable size prior to transplanting the seedlings.

Medium: I use European peat moss (any will do, however), which I wet by throwing it into a bucket half-filled with water. I scoop out the resulting "peat soup" and place it in 6 x 8 inch flats, smoothing the mixture by patting it gently. Avoid squeezing, as the air left in the mixture is important to the seedlings.

The flats are filled to about one inch of the top and over the peat moss I place a lit layer of "No Damp", a commercial brand of sphagnum peat moss. Apparently milled sphagnum is more resistant to fungus and mold than ordinary peat. The seeds are scattered on the top of this layer, trying to obtain a spacing of one-eighth of an inch or more between the seeds. Finally, I dust a layer of milled sphagnum on top of the seeds. This is easily done if one uses a sieve from about a one foot height. A pane of glass is now placed on the flat and it is moved to a window. The window I use gets about two hours of sun in the late afternoon. Sunlight appears to kill mold, and I consider some sun essential.

The medium is carefully watched for mold and if it appears, the glass is removed for a day or so. It is also necessary to mist the medium every day or so. This, too, seems to prevent the growth of mold. As the seeds germinate, the edges of the glass are lifted with matchsticks so that air gets at the seedlings and they become accustomed to lower humidity. Finally the glass is entirely removed.

Seedlings: A careful watch of the flats is now necessary lest they dry out. It is necessary to mist them every day or two and to water the flats when they seem dry. My method is to take them to the sink and let them float until almost submerged. I then drain them by tipping. After the seedlings have been up about one month; I fertilize with a fish type fertilizer, which I mix in a watering described above. From then on this is done every other watering.

I have begun to experiment with fluorescent lights. My experience so far suggests that although this produces excellent growth, the seedlings are sensitive to sunlight and are not as tough as seedlings, which have not had artificial light.

Transplanting: About May 15 I transplant the seedlings directly into outside beds. As far as I know, this is not the usual and accepted practice. I use beds made out of 1x6 inch red wood set edgewise of the surface of the ground and about three feet on a side. The exact size is chosen to hold an old window screen to be placed on top of the bed. Inside the bed the ground is covered with three inches of peat moss, which is mixed into the soil. The result is a slightly raised bed about the surrounding soil to provide drainage. The seedlings are inserted two inches apart and the screen placed on top of the bed. The screen is absolutely necessary as it breaks the force of strong rains, provides shade and blocks the wind. When the seedlings are first transplanted, even the screen does not provide sufficient shade. Therefore, on top of the screen I scatter pine needles, dense enough so that almost no direct sun falls on the seedlings. These needles are gradually removed beginning in a week or two. In September, the screen itself is removed so that the seedlings can harden off. The seedlings require frequent watering during the entire summer and this is done through the screen. In November, pine or juniper boughs are placed over the seedlings, enough to cover them, but not so thick as to smother them.

In April of the following year, I remove the boughs, but do not replace the screen. Perhaps 20-50% of the seedlings have died during the winter or will die within the month, but the remaining seedlings are very tough. It may be of interest to know that my beds get about 2/3rds sun during the middle of the summer, with shade only in the late afternoon and morning. Also, my beds are on Cape Cod, a climate suitable for growing rhododendrons. Perhaps the method described would not be suitable for a more severe climate.

I have tried in the past to keep seedlings in flats and store the flats in the shed in the winter. The losses were virtually total and were probably the result of drying out both in winter and summer.

I can, however, offer a final recommendation--experiment and find something that works for you. I am convinced that many conditions not mentioned in an article of this type (kinds of soil, micro-climate, special idiosyncrasies of the grower) all have a strong bearing as to whether suggestions such as mentioned in this article succeed. Other hazards such as children and dogs take an equally high toll! Nonetheless, persevere and, as one famous English rhododendron enthusiast suggested, "when you see your own crosses blooming for the first time you will have had six years of happy waiting and only one day of disappointment!"


This issue of the "Rosebay" is innovative in a number of respects. First of all is size; this is the largest issue to date. Secondly, is an attempt to carry a theme throughout the issue, this time focusing on growing rhododendron from seed. Jon Shaw's fine article shows what an ambitious amateur can and is doing right here in Massachusetts In conjunction with this, we are reprinting from "Sunset" a fine West Coast magazine, an article dealing with the construction of a growing stand for rhododendrons.

Another new feature is a series titled, "A Visit with...". Its purpose is to introduce our members to each other and to let all of us know what's happening in the other fellow's garden. The editors asked our good friends, Past President and Mrs. Louis Cook, to lead this series off and the article submitted was just what we wanted. Hopefully this will encourage others to share their gardens with us.

A letter from Heman Howard is tempting with promises of Dexter Hybrids from Heritage Plantation.

We will also print the secretary's report of all chapter meetings from now on.

Perhaps you noticed from the masthead that the "main office" of the "Rosebay" has drifted out to sea. On February 1, the editors and their two hybrid seedlings packed to the lovely island of Nantucket. To our knowledge there isn't a rhododendron on the island but conditions appear to be ideal. We plan to bring about 1.. rhodys and azaleas over in the spring and then hope. Please note the address change, though, for future communications to the "Rosebay".


Three years of rhododendron growth in a single season - that is what an amateur grower in Bellevue, Washington, accomplished after using a simply designed growing bench with controlled lighting. No heating cables are used; his basement bench is subject to normal indoor temperatures. The designer Dr. Edwin C. Brockenbrough, attributes this phenomenal rate of growth (which produces plants with flower buds in as little as two years) to special light control under optimum growing conditions and the early planting of freshly harvested seed. Four special plant-growing fluorescent light tubes are installed 18 inches above the frame and controlled by an automatic timer on top of the bench. Additional light reflects from white vinyl plastic side curtains. These also serve to maintain an even level of heat and humidity. Ends are left open to permit free circulation of air. Rhododendron seed is planted in October or November in covered plastic trays placed on a gravel bed. The fine seed is scattered on a surface of moist sphagnum moss. Boxes are then placed under the lights and exposed to 18 hours of daylight. During December and January, seedlings get big enough to be transplanted into open plastic trays. By June, these are husky little 3 to 4 inch plants ready to go outdoors to a shaded location for the summer where normal daylight hours approximate the controlled indoor lighting. The plants can be expected to reach the size of normal three-year-old rhododendrons by September. When uncovered for the first time, the tiny seedlings are watered several times a day with a syringe spray. This keeps the roots moist, and the damp surface of the rooting medium helps maintain a high level of humidity. The young seedlings get an application of diluted fish fertilizer at two-week intervals after transplanting. When they go outdoors in June and July, the feeding program is stepped up in frequency and strength.

Temperature in the growing bench during the hours when the lights are turned on is about 70 degrees F. During the 6 hours of darkness, the temperature is permitted to drop to 60 degrees.


Speedup for rhododendrons

(reprinted with permission from SUNSET MAGAZINE, Menlo Park, California)
Redrawn from SUNSET J. Slavitz


My interest in rhododendrons started as a boy. My grandfather in So. Weymouth, Mass. had several on his place. Later as a young man I moved to Everett and Seattle, Washington, where I really became interested. On returning to New England, we bought two acres of land in an oak and pine grove on Furnace Pond, Pembroke, which is also about 15 miles from the ocean. My wife Irene and I decided to plant some rhododendrons on the place.

One day as we were riding by a wooded plot, miles from nowhere, we found a large planting of rhododendrons. Upon inquiry, we found out the owner was going out of the nursery business. We went to his house in another town to buy a few rhododendrons and when I came out I owned seven hundred six to eight foot named hybrid rhododendrons.

After planting a few of each on our land, being an auctioneer, I decided to hold a plant auction. Now each year we hold seven rhododendron auctions plus the one we hold for the Mass. Chapter of the American Rhododendron Society.

We now buy closeouts of rhododendrons, azaleas and other plants from various nurseries. The first forty-five minutes of the sale we show color slides of rhododendrons and talk on raising and propagating them. Most of the people coming to our auctions hare had no contact with rhododendrons. We sell these rhododendrons at prices below ordinary nursery prices in order to interest the people in rhododendrons. We recommend nurseries where they can get additional plants and for many people who are interested, we recommend that they join the Rhododendron Society. We hare found that this has created a great interest in rhododendrons and the nurseries' sales are increasing because of this.

Perhaps people in other parts of the country might be interested in the species and hybrids that we now grow on our land.

The following is the list:
RHODODENDRON SPECIES: carolinianum, carolinianum album, minus, concinnum, calophytum, decorum, discolor, catawbiense, catawbiense album, catawbiense compactum, fortunei, hipophaeoides, laetivirens, maximum, micranthum, mucronulatum, pemakoense, praevernum, smirnowii, sutchuiense, ungernii.

NAMED HYBRIDS: 'Album Elegans', 'America', 'Amethyst'(Dexter), 'Anna Krushke', 'Bessie Howell', 'Blue Peter', 'Blue Tit', 'Boule de Neige', 'Bric a Brac', 'Britannia' X fortunei (Tony Consolini), 'Caracatus', 'Caroline', 'Cary's Red', 'Cawt. Album','Cawt. Boursault', Cawt. Virgin', 'Chionoides', 'Cotton Candy', 'Cunningham's White', 'Cynthia', Dexter Hybrids many unknown, 'Dora Amateis', 'Dr. Dresselhuys', 'Dr. Rutgers', 'Ed Cary', 'Edward S. Rand', 'Elie Shammarello', 'Elizabeth', 'Ethel V. Cary', fortunei 'Lu Chien', 'Giganteum', 'Gloxineum', 'Goldsworth Yellow', 'Gomer Waterer', 'Harvest Moon' (Comerford), 'Hymer', 'Inamorata', 'Ignatius Sargent', 'Irene Cook' (Jack Cowles), 'Jan Dekens', 'Lee's Dark Purple', 'Leo', 'Lennroc' (Mezzit), 'Mars' X 'P. den Ouden' (Cary), 'Mrs. C. S. Sargent', 'Mrs. Furnival', 'Mrs. P. den Ouden', 'Mrs. William R, Coe' (Dexter), 'Mrs. Tom Lowinsky', 'Naomi Astarte', 'Naomi Nautilus', 'Naomi Sky Glow', 'Old Port', 'P.J.M.' (Mezzit), 'P.J.M. Victor' (Mezzit), 'Pink Pearl', 'Pioneer' (Gable), 'Prof. Bettex', 'Purple Gem', 'Purple Splendor', 'Purpureum Elegans', 'Purpureum Grandiflorum', 'Ramapo', 'Roseum Elegans', 'Roseum Superbum', 'Sappho', 'Scintillation', 'Tony' (Shammarello), 'Westbury', 'Weston' (Mezzit), 'Wheatley' (Dexter), 'Vulcan', 'White Gem' (Mezzit), 'Windbeam' (Nearing), 'Windsor Ladd', 'Yak X Purple Splendor' (Comerford), 'Years of Peace' (Mezzit).

I must warn some of our New Englanders that we have a microclimate here and some of these named hybrids might not survive 30 miles inland.

We also have many unnamed hybrids that I have selected for their beauty.

Submitted by Louis A, Cook, Ridge Ave., Pembroke, Mass.


National has informed "Rosebay" of an important questionnaire to be included in the January bulletin. This questionnaire represents much expense and effort and National deems it very important. Please take a few minutes of your time to complete it and. mail it as soon as possible.


Oct. 7 Afternoon at the Case Estates.
Heman Howard and Jack Cowles conducted a short tour of the grounds.
Heman Howard asked members who were interested in acquiring named Dexters at $8.00 each to contact him,
Max Resnick reported on the successful show and auction. It was reported desirable to have the Past President on the Board of Directors. An amendment to the Constitution will be voted to make this change at a later date,
A report on Stanley Park is to be made by Dick Leonard.
Jane Brooks has agreed to take over the purchase and sale of books; will make arrangements with Elinor.
Jack Cowles introduced Jon Shaw.
In April Jon visited gardens in Holland, Belgium and Germany. Dietrich Hobbie in Germany grows predominantly repens hybrids on low-lying land cut by drainage ditches and shaded by pines.
The little-known Bremen Botanical Gardens are the center of the German Rhododendron Society, and very much worth a visit. Here were 'Canary' (caucasicum x campylocarpum) of extraordinary quality as well as williamsianum hybrids, other dwarfs, shrub collections and rock gardens.
The Keukenhoff bulb fields of Holland are surprisingly hilly and the acres in bloom a sight to be seen to be believed.
The first slides were of a Norwegian experimental garden (Risholmen) on a tiny island. The soil is generally chalky, so the rhododendrons are planted in peaty areas. About 145, mostly standard iron-dads and azaleas, have been established. 'Dr. C. H. Felix' was a conspicuously vigorous bright pink.
In May, Jon visited several English gardens as well as the Chelsea Flower Show.
Sissinghurst Castle has many interesting architectural features including an amusing herb seat and a traditional cottage garden. A beautiful yellow peony (P. lutea ludlowii) and Corsican hellebore (Christmas rose) were showy.
Windsor Castle and Great Park made another outing. Here Savill Garden featured many splendid rhododendrons including: 'Venessa Pastel'; R. Cinnabarinum grown as a tree; a gorgeous low red 'Waley Hyb' x 'Queen of Hearts'; 'Fabia Tangerine' with large calyx development; 'Dido'; and wardii 'Medow Pond'. Pieris forrestii was also of note.
The Chelsea Flower Show is held at the height of the flowering season and has outdoor displays such as rock gardens as well as exhibits under the tent. Sunningdale had a magnificent pyramid of yakushimanum hybrids featuring their named Seven Dwarfs.
Hilliel's Nursery is beautifully laid out with rock garden plants displayed in screen beds. The most striking rhododendrons there were 'May Day' and 'Mrs. Lionel de Rothschild'. The Royal Horticultural Society's display gardens at Wisley are a rhododendron lover's Paradise. A surprise was 'Furnival's Daughter' which produces gorgeous bloom on a very fine plant. 'Elizabeth Lockhart' was through blooming, but the bronze foliage very pretty. R. bureavii had attractive "candles" of new leaves. Both 'Moonshine Supreme' and 'Moonshine Crescent' are outstanding yellows, but the 'Supreme' is a better plant. The Exbury form of yakushimanum is now a fine plant. R. dichroanthum type 'Jasper Pimiento' has been used for hybridizing by Dave Leach. And last but not least was the orange 'Tiger'.
Kew was the last garden visited in England. Here the two-toned 'Coral Star' and 'Lady Roseberry' were at their peak.
Of great interest was the lovely plant of Azaleadendron 'Torleoanum'.
Jon's photography is superb and all agreed that his lecture was one of the greatest.

Wed., Nov. 7, 7:3. p.m. at Weston Nurseries, Hopkinton. A report on the previous meeting was made and accepted.
A thank you note has been sent by Max for the cuttings from Heritage Plantation now being rooted at the Hunnewell Estate.
A letter from the Pres, of A.R.S., Alfred A. Martin, requested donations for the seed exchange, histories of chapters, and their schedules, if possible, and nominations for awards. Several publications are now in progress including a book on Eastern hybridizers.
It was voted to amend the by-laws so that the President ex-officio be on the Board of Directors. Carried.
Jack introduced Judge Bishop Von Wettburg who spoke on "The Hardgrove Rhododendron Hybrids".
In 1964 a meeting at Planting Fields led to an interest in Don Hardgrove's work. His general aims included: shapely habit; ease of culture and propagation; early and consistent flowering and insect resistance. He preferred large flowers, bright colors; dwarfness and hardiness, fragrance and plants which would extend the blooming season.
He used a wide range of tender species: griersonianum, calophytum, campylocarpum, wardi and williamsianum. He felt that one would probably have to dip into Catawba for hardiness and used 'Catalgla' and 6th generation 'Powell Glass'. He found that offspring of 'Mrs. C. S. Sargent' will root, that 'Meadowbrook' produced hardiness, and that he could get clear purples out of 'Purple Splendor'.
Among the lepidotes, he liked white carolinianum best and thought a cross between R. maddenii with R. boothii could be compatible with hardy crosses. Some unsuccessful crosses were tried many times, occasionally with surprising results. Yakushimanum he liked as a species, which he felt was equal to any of its hybrids.
Many fine slides were shown. Of note were: a particularly lovely form of 'P.J.M.' by a pond; a choice pink catawba in the Blue Ridge Mountains; Carolinas in the wild growing on almost bare rock; a nice carolinianum x augustinii hybrid; a pure white seedling of kaempferi x poukhanense; and some gorgeous views of Portland with seedlings of Lem's and plants at Cecil Smith's. For the benefit of photographers, various techniques were pointed out to achieve dramatic effect.


Dear Friends and Members:
Would you be interested in a program whereby it would be possible for you during a (>5 year) period to obtain (6-10) of the best named Dexter rhododendron cultivars?
During the past three years Heritage Plantation (the former Dexter rhododendron estate) has been making a sincere effort to locate and return to the place of their origin the many named cultivars of this nationally famous group of rhododendrons.
Many requests have been received by us during this period asking where certain cultivars might be obtained. In most cases sources were located only to find the nursery does not ship, making it necessary to go in person to obtain your plants.
Heritage Plantation is considering the possibility of creating a program whereby rooted cuttings of (6-10) cultivars would be obtainable over a (>5 year) period. It is our desire to give rhododendron enthusiasts from coast to coast the opportunity to obtain these plants and have them mailed to their homes.
It should be understood that Heritage Plantation is not going into the nursery business. These cuttings would be rooted by a professional rhododendron propagator, then the rooted cuttings would be handled by a commercial concern equipped to package and ship those 8-10 inch rooted plants.
These plants will be guaranteed to be true to name and to arrive in good condition. The price per plant, with two being offered each year, one each spring and fall, will be $8.00 per plant. Members of Heritage Plantation will receive their usual discount.
Dexters like all other rhododendrons, prefer acid soil and will tolerate low temperatures of zero to five above. This will include all of Zone 6 as well as protected areas in Zone 5. If plants are expected to withstand minimum temperatures, consideration must be given as to planting location. Some protection should be given against exposure to strong winds.
Because of the time required to propagate these plants this program would be scheduled for the spring of 1975. Before proceeding, however, an estimate of the number of people interested is necessary, Your reply will be appreciated. This is merely a survey and a "yes" reply is not binding in any way. You will be informed when this program goes into operation.
Sincerely, Heman A. Howard, Horticulturist.

The chapter has received from Heman Howard on behalf of Heritage Plantation of Sandwich, over one hundred cuttings of various Dexter Hybrids. These scarce cuttings are being propagated by Jack Cowles and hopefully will be the nucleus of a future collection of the chapter. Many thanks, Heman,
National informs us of a critical shortage of material for the seed exchange. Anyone who has seed to forward to Esther Berry and has not done so as yet is urged to send it immediately. None of us would like to see the success of this important project be even partially impaired.


  1. Proceedings of the Breeder's Symposium of the Pittsburgh meeting.
  2. A twenty-five year index of the ARS Quarterly,
  3. Final information about the Society's new book.
  4. A major volume on the work of the Eastern hybridizers.

P.S. Books now available from:


Mr. and Mrs. Donald A. Freeland
541 Norfolk St.
Holliston, Mass. 01741

Rudolf Behring
744 Giroux St.
Dorothee Laval
P.Q. Canada H7x 2J3

New York Chapter
Mrs. Walter McKay, Sec'y
55 Ninth Ave.
King's Park, N, Y. 11754

Miss Virginia Salzman
7 Valentine St.
West Newton, Mass. 02165

Mr. and Mrs. Robert P. King
76 Great Plain Ave.
Wellesley, Mass, 02181

Potomac Valley Chapter
Mrs. Raymond H. Goodrich, Sec'y
10015 Saddle Rd.
Vienna, Va. 22180

Mr. and Mrs. Robert G. Carlson
Carlson's Gardens
Box 305
South Salem, N. Y. 10590

Mr. and Mrs. Rudolph Harnoi
P.O. Box 141
West Barnstable, Ma. 02668

Mr. and Mrs. Fred Leonardi
1305 Main Street
Hanover, Mass. 02339


Jane Goodrich, Potomac Valley Chapter, writes: 'If anyone in your chapter is growing Gable Rhododendrons, ask them to contact me. We are anxious to hear from H-l climates. Our chapter is doing research on the Gables." Address: Mrs. Raymond H. Goodrich, Sec'y 10015 Saddle Rd. Vienna, Va. 22180