Summer annuals, dahlias, and tulips are planted in changeable expositions.
The exposition of summer annuals is made up of looking for new cultivar seeds from world botanic gardens and gardening firms to show and recommend gardening novelties every year.
Every year in the garden you can see multiform collection of dahlias with more than 280 cultivars. All main cultivar groups of dahlias are presented.
Also interesting, are collections of bulbous plants – tulips (more than 300 cultivars) and narcissus (about 150 cultivars).
Near the Old Park there are iris beds. In the collection, 40 species and 150 cultivars of irises are presented. They stand out sharply against the background with their smart flower form and diversity of colour.
There are about 75 species of hydrangeas in the world which are found in East Asia (China, Japan, Korea, Indonesia, Himalayas) as well in America. Most of them are growing as shrubs, but there are also some lianas. Hydrangea cultivars, which there are now several hundreds in the world, became more popular in Latvia in the last decades. In the National Botanic garden you can see 7 species, 2 subspecies and 47 cultivars of hydrangeas.
The historic part of the botanic garden, Old Park was planted in 1932. Here you will find some trees planted in from the 20-30ies of the last century – Norway maple ‘Schwedleri’, Crimean linden and laciniate linden. Here you will also find the honey locust with many branched thorns growing directly from the trunk.
The park is wonderful in all seasons. In spring, the sparkling white snowdrops bloom exuberantly, and the bumblebees buzz in the multicolour corydalis flowers. The Japanese lilac trees and rhododendrons are smelling sweet. The petals of white-fringe trees remind you of snowflakes in the early summer. The American tulip-tree blooms when tulips are long faded. Noble solitude surrounds the local purple-leaved form of the common oak found in the forest in Stelpe near the “Timuki” house. Different species and cultivars of conifers grow among a large variety of magnolias.
In the old park, there is also a bed with 48 cultivars of Hostas placed inside. Hostas are suitable for shady places, but can also grow full sun. They are decorative all season, even without flowers. Leaves of cultivars are variegated, undulated, and covered with bluish bloom.
Rugosa hybrid roses of Latvian breeding
You can see in the collection 23 cultivars of Rugosa hybrid roses bred in Latvia. A major and invaluable contribution in the breeding of this group of rose varieties in Latvia and in the entire world is NBG researcher Dzidra Rieksta, who dedicated her life to growing and breeding roses, and created 22 cultivars. The main goal by breeding her Rugosa hybrid roses was to create a very important feature for Latvian climatic conditions – winterhardiness. They easily sustain our winters without covering and form 0.5-2 m high vigorous, densely branched shrubs. Roses of this group usually start to flower 10-15 days earlier than cultivars of other groups, and have rich, almost uninterrupted flowering until the autumn frosts. Flowers are fragrant, and the aroma differs between the cultivars. Rugosa type roses are also decorative with their vitamin rich orange fruits, more juicy and delicious than in other groups.
Plantings of perennials are placed in several places in the central part of the garden. Most represented are irises, astilbes, hostas, lilies, daylilies, peonies, and phloxes.
Our collection of daylilies (Hemerocallis) contains more than 120 cultivars. It is a relatively new ornamental culture. The first cultivars of it were created only in the end of the 19th century. Daylilies start to flower in the end of May, and some cultivars continue to flower through September.
Next to daylilies are plantings of peonies. Cultivation of this flower comes from China, but in Europe mostly French, British and Dutch breeders were involved in its breeding process. The NBG has a collection of more than 140 cultivars that are presented, between them are 16 of Lithuanian breeding.
Next to the central part of the garden are plantings of astilbes, ligularias, helenias, winter asters and other flowers of the Asteraceae family.
There are 20 species and 125 cultivars of astilbes in the collection. They are placed according to colours, keeping in mind also their height. Astilbes flower from the second half of June to the end of August, but also in the spring, when the leaves are coming out, the bed is bright and colourful in its brownish green to bright reddish brown colours. Astilbes keep their decorative looks until the late autumn, thanks to graceful and colourful leaves.
In the second half of summer, 47 taxa of perennial asters (Aster novae-belgiae, A. novae-angliae) start to flower; as well 7 taxa of fleabane (Erigeron), 15 taxa of Ligularias, as well about 100 taxa of other plants from the Asteraceae family. They flower until the deep autumn frosts in October.
The NBG rock garden was created in the time period between 1961 and 1965 after the project of I. Davidsone and A. Pone, and in general saved its view until now. Plants are arranged in several terraces and are standing out sharply with beautiful flowers starting from the early spring. Here visitors can become acquainted with more than 400 plant taxa, including interesting perennials, rare bulbous plants, small shrubs, etc.
In the Botanic garden rosary you can see more than 300 cultivars most suitable to Latvian climate, from eight different cultivar groups:
- Floribunda roses;
- Shrub roses;
- Hybrid rugosa roses;
- Climbing roses;
- Polyantha roses;
- Ground covering roses;
- Miniature roses;
- Hybrid tea roses.
There are more than 30,000 rose cultivars known in the world, and every year many new ones are registered. Most of them can’t be found in Latvia, because our climate is not suitable for them. But, the common number of rose cultivars grown in Latvia is near to two thousand.
Summergreen and wintergreen rhododendrons grow as shrubs, rarely as trees. They are spread in all continents except Africa and Antarctica. The larger number of Rhododendron species grow in China, Tibet, Myanmar and Nepal. In the genus Rhododendron there are more than 1,000 species and many thousands of cultivars.
NBG Rhododendron collection contains 70 species and about 90 cultivars of rhododendrons, among them 28 Latvian cultivars bred in the rhododendron breeding station “Babīte” by famous breeder Rihards Kondratovics. Those cultivars you can observe in a special exposition alongside the main road.
Heaths and Heathers
The genus heath (Erica) contains 850 species. Most of them are spread in Africa, especially South Africa (Cape heaths), the remaining species are native to Madagascar, the Mediterranean, and Europe. Only the cross-leaved heath (Erica tetralix), which is one of the protected species of Latvian flora, grows natively in Latvia. In the NBG collection there are 8 species and about 50 cultivars of heaths.
All heaths and heathers in our collection are small shrubs with evergreen needle-like leaves. The earliest flowering is winter heath (Erica carnea) – its cultivars in Latvian conditions flower in early spring. Other heaths flower in summer, and heathers pick up the baton of flowering in the end of August. Taking in mind decorative autumn and spring colouring of several cultivars’ leaves, the heather garden may be decorative almost all the year.
Aspens and poplars
Aspens and poplars systematically belong to one genus – Populus. To this genus belong summergreen trees spread in temperate zone of Europe, Asia, North America and North Africa. The peculiarity of this genus is possibility to hybridize relatively easily between different species, which makes this genus difficult to research for systematic botanists, and number of species in it by different authors varies from 25 to 50 and more. In the arboretum you can see 150 varieties of aspens and poplars.
The conifer collection of NBG contains about 900 taxa, among them about 600 ornamental cultivars and forms. It is one of the largest collections in Northern Europe. Excerpt of 4 conifer species native for Latvia – Scots pine (Pinus sylvestris), Norway spruce (Picea abies), common juniper (Juniperus communis)and European yew (Taxus baccata),in the garden you can familiarize with many foreign conifer species and their forms.
Brightly grown in the Riga city parks, common horse chestnut (Aesculus hyppocastanum) comes from Bulgaria and Northern Greece. For the first time trees of horse chestnut were planted in Latvia in the beginning of 18th century, when Peter I ordered to bring some trees from Danzig (now Gdansk), and plant them in front of the house in Riga that was given to him. Besides common horse chestnut, there are about 20 other Aesculus species, natively spread in North America and eastern Asia.
Let’s mention that horse chestnuts (Aesculus) are not close relatives to the edible chestnut (Castanea sativa); their nut-like seeds are moderately toxic but are used in folk medicine. In the NBG you can see 6 species and 3 hybrids and 5 cultivars of horse chestnuts.
For rose (genus Rosa), the species is characterized by a bright diversity of species and forms and hybridizing possibilities. That causes lack of consensus between specialists about the number of species in this genus: after views of different authorities it varies from 100 to 1000. Rose species are brightly spread in the northern hemisphere – in Europe, Asia, and North America.
In the collection of the National Botanic Garden about 50 rose species are presented.
There are 4 species of witch hazels (Hamamelis) that are known. Two of them are native to North America, one to Japan and one to China. They are ornamental deciduous shrubs or small trees, and are used in medicine and cosmetics.
In the National Botanic Garden collection there are all 4 witch hazel species presented, as well as one interspecific hybrid and several ornamental cultivars.
The forming of the greenhouse collection found in the botanic garden was started in 1956. The main source of its forming and replenishment is international seed exchange with other botanic garden, and most plants are grown from seeds or cuttings. At the present moment, more than 2000 taxa from all continents except Antarctica, can be seen in the conservatory.
The new conservatory building has been opened for visitors since the 25th of April 2015. There are 4 halls accessible for visitors: Succulent’s hall, Warm subtropics hall, Cool subtropics hall, and Tropic hall.
The conservatory is especially proud of the collection of succulents. There are notable diversity of aloes and agaves – more than 30 taxa of each genus. There are also gasterias (20 species), peperomias (20 taxa), kalanchoes (15 taxa), euphorbias (13 species), as well as sansevieras, cactuses with long thin trunks, like selenicereus, eriocereus, and other quite exotic succulent lians.
Cactus collection contains more than 600 taxa. There are also plants of Crassulaceae family, like Crassula (50), Sedum (40), Aeonia (20), and others, as well 17 species of Aizoaceae family.
In the orangery there are several fruit trees growing – not only relatively usual lemon trees, but also such subtropic fruit plants like Feihoa, Psidium, and Eriobotria. Let’s not forget also bananas, though they are not trees but huge herbs.
Since the new conservatory was built the visitors can also observe the hothouse plant collections which are not accessible for visitors, but are visible through the glass walls in other 9 halls: there are Pelargonium and Aryranthemum hall; Cyclamen hall; Gerbera hall; Chrysanthemum and Alstroemeria hall; two Woody Plant Propagation halls; Wild Bulbous Plant hall; the Hall of Orangery Plant Propagation and Sanitation, which is also dedicated to act as a rescue center for plants confiscated for infringement of plant trade laws (according to Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora - CITES).
By visiting orangery please take in mind that there are also spiny, sticky, and poisonous plants. Contact with them can cause allergic reactions, irritation, and other health problems.
Food, Medicinal and Technical plants
In the exposition of food, medicinal and technical plants you can see about 700 plant taxa. Especially notable, and relatively new, are the American cranberries (Vaccinium macrocarpon). There is already quite a good spread in our Latvian household - American cranberries highbush and rabbit-eye blueberries (Vaccinium corymbosum, Vaccinium ashei) which distribution in Latvia started from here 40 years ago. You can see also other less or more traditional berry plants, such as edible honeysuckles (Lonicera coerulea L. camtchatica a.o.), rowan trees (Sorbus), mini kiwi fruits (Actinidia colomicta), black elders (Sambucus nigra), black, red, and golden currants (Ribes nigrum, R. rubrum, R. aureum), as well as collections of hazels (Corylus avellana) and hops (Humulus lupulus).
In the National Botanic Garden collection there are 15 walnut tree (Juglans) species from about 40 kinds known in the world.
Walnuts are found throughout the broad-leaved forests in the both hemispheres. There are no native Latvian walnut species, only occasionally some more hardy trees are grown in the parks. All species have big pinnately compound leaves. In the spring, leaves form and later long aments of male flowers fall down. Less visible female flowers form nuts. Most commonly known are the Persian walnut (Juglans regia). It is not winter resistant in Latvian conditions. Breeding of more resistant walnut forms was the aim of research work of academic Alfreds Ozols in early 60-ies, who was also the initiator of organizing our botanical garden, as a heritage of his work several Juglans hybrids are still growing in the arboretum.
Excerpt of very characteristic for Latvian flora silver (warty) birch (Betula pendula) and downy (also white, moor, or hairy) birch (Betula pubescens) in the NBG arboretum there are planted about 66 species (about a half of all world’s known) and 6 hybrids and 10 cultivars. You can see Latvian rare species dwarf birch (Betula nana), North American paper birch (Betula papyrifera), Young’s weeping birch (Betula pendula ‘Youngii’) and other.
The genus oak (Quercus) belongs to the beech family (Fagaceae). There are about 250 species of oaks in the world.
In the NBG arboretum you can see 30 species from Europe and North America. There are also 7 ornamental oak cultivars, including one of Latvian provenience – Quercus robur ‘Timuki’, who’s leaves become reddish purple in midsummer.
Hornbeams (Carpinus) belong to the birch family (Betulaceae). There are about 30-40 species of hornbeams known in the Northern hemisphere, most of them growing in China. In Europe there are two species, and one – the eastern part of North America. The common hornbeam (Carpinus betulus) grows in Southwestern part of Latvia and is a Latvian protected rare species.
All together in the NBD collection are 9 species and 4 cultivars of hornbeams.
Beeches (Fagus) belong to their own family (Fagaceae). There are more than 10 species of beeches known, growing in Northern hemisphere – in Europe, Asia and North America.
In the NBG collection there are 3 species and 10 cultivars of beeches.
In the genus lime (Tilia) there are about 50 species, but native for Latvia is only one species – small-leaved lime (Tilia cordata).
In the NBG collection you can see 30 species, subspecies, varieties and forms, as well 8 cultivars of limes.
There are about 500 species of barberries (Berberis) in the world. They grow in both moderate and subtropic climate zones, except Australia. The richest species diversity is in South America, Africa and Asia. In the collection of NBG there are 50 species and 30 cultivars of barberries.
Ashes (Fraxinus) belong to the family Oleaceae, together with the olives and lilacs. There are about 65 species of ash trees in the world.
In the NBG collection there are 15 species and 5 cultivars of ashes.
Willows (Salix) belong to their own family Salicaceae. There are about 300 species of willows in the world known, 17 of them are native in Latvia. The use of willows and osiers is quite broad: in ornamental plantings, for ground stabilization, some species are good melliferous plants, some are used for plaiting, and have important medicinal use: let’s remember that our well known aspirin was extracted from the willow’s bark!
In the NBG arboretum there are about 100 species and 80 cultivars of willows planted.
There are 230 taxa (species, subspecies, varieties and forms) and several thousand cultivars of maples (Acer) in the world. Native in Latvia is only one species – Norway maple (Acer platanoides).
In the collection of National Botanic Garden you can see 73 species and 32 cultivars of maples from Europe, Asia, China, Japan and North America.
Euonymus (spindle trees)
Euonymus belong to the staff vine family (Celastraceae). There are about 200 species of euonymus in the world, most of them are tropic or subtropic plants, deciduous or evergreen shrubs or small trees. There are 50 species endemic for China. There are two species native to Latvia: European spindle (Euonymus europaeus) grows mostly in the western part and warted spindle (Euonymus verrucosus) – in Eastern part of Latvia.
In the NBG collection there are 14 species and 10 cultivars of Euonymus.
Cherries (Prunus, syn. Cerasus) are native in Europe and Southwest Asia.
In the NBG collection there are 20 species and 5 decorative cultivars of cherries.
In the rowan species collection there are about 109 species, 7 hybrids, 9 cultivars. Many plants are grown from seeds collected in the wild. Some of the specimens belong to the world’s endangered species, for example Sorbus arranensis, S. bristoliensis, S. devoniensis. In the collection, the Swedish whitebeam (Sorbus x intermedia) is also presented, which rarely occurs in the Western seashore of Latvia.