The Importing and Growing of Ericaceae in Latvia S.S.R.
Translated by Dr. Maksis Eglitis, Puyallup, Wash.
Note: The above article was accompanied by a table listing about 125 species and varieties of the genus Rhododendron now growing in Latvia, with date of importation, source, and other information. Virsu dzimtas augu introdukcija Latvijas PSR DAILDARZNIECIBA V: 5-41. 1964. Latvijas PSR Zinatnu Akademijas Izdevnieciba, Riga, 1964.
In the flora of the U.S.S.R. the ericaceous plants are represented by 21 genera and 46 species, but in Latvia there are only 8 genera with 11 species. Of the 46 species present in the Soviet Union 19 species belong to the genus Rhododendron.
The climatic and soil conditions in Latvia are favorable for growing the ericaceous plants. On the average there are annually 150 to 180 cloudy days and only 30 to 40 days absolutely cloudless. The duration of the winter is about three months. The winter is moderately cool, mostly cloudy, with snow or rain. The snow cover stays stable through all the winter. The permanent frost begins in December. Low temperatures such as -38 to -42° C. are rare and commonly do not last longer than 2-3 days at a time.
About half of the soils in Latvia are acid podzols. About 22% of the territory consists of swampy soils, giving inexhaustible quantities of peat moss.
The first trials to grow imported ericaceous plants in Latvia are known from the first half of the 19th century. The nurseries brought into the market about 20 varieties of azaleas (belonging to R. simsii Planch.) for cultivating in cool greenhouses, and 15 varieties summer green rhododendrons (garden azaleas). From the evergreen rhododendrons there were recommended R. arboreum Smith and some hybrids of this species, R. ferrugineum L., R. hirsutum L., R. maximum L. and approximately 10 hybrid varieties. A little later, about 1860, some varieties of R. luteum Sweet were recommended for growing in the gardens, noting that during the winter these plants must be protected by covering. In the same year one shrub of this species was planted in the cemetery in Vecmokas, Tukums area, where it still is growing and has reached the height of 2.5 m.
At the beginning of the 20th century, in the parks of Riga, were grown seven species of rhododendrons: R. brachycarpum D. Don, R. camtschaticum Pall., R. caucasicum Pall., R. catawbiense Michx., R. cunninghamii Focke, R. hirsutum L., and R. intermedium Tausch, but in a few decades they were all dead. In the following two decades the nurseries and the garden owners began to grow rhododendrons of higher resistance. From the rhododendrons planted about 1924 in the cities Jurmala and Melluzi there are still growing at the present time some shrubs of rhododendrons from America and Japan. Since 1952 these plants have been used for harvesting seeds for propagating seedlings. In the thirties the nurseries imported Rhododendron varieties from England, Netherlands, Germany and other West-European countries. In the forties, because of World War two, and one extremely cold winter, a great number of rhododendrons had again perished.
An extensive program of importing rhododendrons has taken place since the fifties. In 1952 a nursery in Dubulti began to propagate rhododendrons not only to supply Riga, but to cover the needs of the cities and parks of the other republics of USSR. The Rhododendron Nursery in Dubulti is not only the largest in Latvia, but in the whole USSR.
Beginning with 1957 continuous tests of the Rhododendron varieties and species have been running in the Botanical Garden of the Latvia State University. There are being tested over 100 Rhododendron species as to their behavior in the climatic conditions of Latvia.
Since the early fifties a great number of greenhouse azaleas have been propagated in the nurseries at Jurmala, Tukums, Riga and Talsi. About 30 varieties of Azaleas are being grown and the number of propagated plants reaches several tens of thousands.