Landscape architect Aleksander Niine (1910–1975) is the author of the arrangement and design of most outdoor expositions.
The arboretum, established according to systematic (affinity) principles, has the largest surface area. Gymnosperms grow in the eastern part of the arboretum; angiosperms in the middle, southern, and western part. The families of angiosperms (flowering plants) have been arranged in accordance with academic A. Grossheim’s system. The first plants in the arboretum were planted in 1963. However, most plants were planted in the arboretum between 1965 and 1972.
The alpine garden was also established in accordance with systematic principles. In 1970–1973, A. Grossheim’s system served as the basis for planting, and after the reconstructions of 1986–1989, A. Engler’s system was used. In recent years, new plants in the alpine garden have been planted in accordance with ecological-geographical principles.
The other outdoor expositions have been designed on the basis of breeding and historical principles and/or the principles of ornamental horticulture. The rosarium was vegetated in 1964. The exposition of astilbes and irises was established in 1968. The exposition of phloxes followed in 1969. In 1973, the exposition of tall perennials and lilies was established. The exposition of grasses was opened in 1996, followed by the exposition of consumable plants in 2000. The beds in front of the new palm house were also designed in 2000. Crocuses, narcissi, shade-loving bulbous and tuberous-bulbous plants, and lilies were moved to new exposition areas between 2002 and 2005.
The exposition of phloxes was vegetated between 2009 and 2011. The high flower beds for xerophytes next to the glasshouse for subtropical plants were completed in 2012. The exposition of day lilies was moved to its new location between 2013 and 2014. The Garden of Senses was opened in 2015. Consumable plants are exhibited in the garden, with special attention paid to the needs of persons with disabilities. The terraces for endangered lime-loving plants and alpine plants situated next to the glasshouse for tropical plants were completed in the summer of 2016.
The plants in the collections of species have been selected from regions with a similar climate to Estonia, with representatives from as many families and genera as possible. Plants under protection in their respective native lands, rare plants, and endangered plants were preferred in assembling the collection.
The objective of our plant variety collections is to preserve plants from different breeding periods and variety groups, especially old or local varieties.
In total, the outdoor collection includes around 6,500 taxons and varieties.
The glasshouses of the Tallinn Botanic Garden for tropical and subtropical plants were opened to visitors in 1971. Renovation works began in 1998, and our renovated palm house opened its doors to visitors in 1999. The southern and northern wings of the complex were renovated in 2008 and 2008, respectively.
Around 2,000 taxons and cultivars grow in these modern glasshouses, and the collection covers about 2,000 m².
The expositions have been designed on geographical principles. Multifunctional use of the building was the priority in picking plants for the palm house.
1962 can be considered the year of foundation of the herbarium of the TBG. This is the year when the herbarium was entered in the global "Index Herbariorum" database, where it was assigned the acronym TALL. Structurally, the herbarium is part of the Department of Environmental Education of the Tallinn Botanic Garden. More than 95,000 herbarium specimens belong to the TBG herbarium.