The botanical garden was founded in 1803 by Professor G. A. Hermann. He was also its first manager. The construction work and planning of the garden was carried out by the chief gardener I. A. Weinmann. In 1811 Professor of Natural History K. F. Ledebur was elected director of the botanical garden, he faithfully performed his duties for 25 years. Thanks to his endeavours and enthusiasm, the garden grew and today it has reached a size of 3.5 hectares. Memorial plaques as well as monuments in the park keep the memory of famous botanists working for the welfare of the Botanical Garden alive.
In front of the greenhouses is the Department of Plant Systematics, established in 1870. This collection helps students grasp the basics of botany, and for plant lovers, it provides a great opportunity to learn about rare species.
To the right of the main entrance is the annual plant garden, where plants are arranged according to their region of origin. The collection contains about 300 species of annuals, including many bulbous and tuberous plants that flower in spring and early summer.
In front of the palm greenhouse, dicotyledonous plants are planted according to the system of botanist Adolf Engler. This universally recognised system, which is used by many botanical gardens to this day, is characterised by the fact that plants are presented along the line of their evolution. There are about 800 species of plants in this collection. Both annual and biennial crops are represented here. Among the dicotyledonous plants represented, one can see such unfamiliar Estonian cultivated plants as lentils, artichoke, buckwheat, flax, tobacco and others.
The park of the botanical garden occupies a large part of it. It is divided into 3 divisions: the European, North American and East Asian divisions. A valuable exhibit in the European section of the park is Estonia's "thickest" maple tree. In the East Asian section, old hazel grows, as well as Amur velvetrees and different species of maple. Herbaceous plants of the same natural area grow under the tree crops. The Minneota Grove in the North American section of the park was created on the same principle.
The park features a collection of perennial ornamental plants. On the southern slope there are plants rare for Estonia, such as ginkgo biceps and tulip liriodendron. Behind the castle wall is a collection of more than 60 varieties of irises. In the other half of the garden is a large collection of peonies, consisting of 250 varieties. This garden of peonies, which blooms from mid-June to the end of July, was created in 2004.
On the Emajõgi side of the river is a garden of clematis, blooming from the end of July until frost. The colour range of the collection varies from white to dark red. The species diversity of flowerbed plants changes every year. Every year the flowerbeds are tried to be decorated with new and rarer species of plants. The largest flowerbed is located on the left side of the palm greenhouse. In the centre of the garden, in the hollow and on the slopes of the former St. George's Bastion, there is an alpinarium. Most of the plants are native to the upper limit of the forest belt and alpine mountain meadows.
In the eastern corner of the garden is a rose garden with around 250 species of roses. This corner of the garden attracts visitors with its bright and varied palette of colours during the mass blooming of roses and beckons with a wonderful bouquet of fragrances. In the western part of the botanical garden, plants of Estonian flora are represented.
There are 58 species of palm trees in the palm greenhouse. The oldest is the 90-year-old Canary date palm. The tallest is the Washingtonia filiformis, which is 20 metres tall. Bananas grow in the right corner, and underneath them is a pool where fish and water turtles swim. In addition, the greenhouse is home to a wavy parrot, a nymphal parrot and a Senegalese parrot.
The subtropical greenhouse contains plants from all continents of the subtropical belt. It has plants from Australia, Africa, New Zealand, Japan, America, and other countries. The tropical greenhouse features mostly plants brought from the Americas.
The succulent greenhouse, which covers an area of 100 square metres, has approximately 600 species of plants. There are various species of aloe, aeoniums and fatbergia. There are also plants from the cactus and agave families. The oldest and largest cactus in the greenhouse is Echinocactus gruzon, popularly known as "mother-in-law's chair".
