This period begins at the end of World War II in 1945. During the war the rose industry did not progress and the areas under rose were reduced, many of the gardens were left without cares. A number of the distilleries were in poor technical condition.

On May 22, 1945, was passed an act, which was intended to recover the cultivation of essential oil plants and upgrade distilleries. The Bulgarian Agricultural Bank established a monopoly over the purchase of roses and got the production and trade in rose products under its control. The long practice of all private companies, manufacturers or merchants, came to an end. World-famous Bulgarian companies that had erected up-to-date distilleries and had maintained the reputation of the Bulgarian rose oil in the face of foreign perfumeries for so long were closed down. The transition to a state-controlled rose industry was given a start.

In the first years of this fourth period, the quantities of rose oil produced were as follows:

1945 - 850 kg
1946 - 794 kg
1947 - 292 kg

No rose concrete was manufactured.

The State-owned Bulgarska Rosa manufacturing and trading company was set up on April 6, 1948 with the aim to consolidate and develop the rose industry.

Three regional subsidiaries for production of essential oils were set up under this company in the towns of Kazanlak, Karlovo and Plovdiv. The Bulgarska. Rosa company was under the direct control of the Ministry of Foreign Trade. However, its chief tasks were to provide regular purchase of essential raw materials by contracting manufacturers, to maintain, construct and use distilleries and extraction installations.

The private distilleries were nationalized. The eight extraction installations with 42 extractor units of total capacity of 43400 liters were also nationalized. The cooperative distilleries were leased to the State Company Bulgarska Rosa. It established a control over a total of 95 installations. No other country in the world could boast so many installations for processing of essential oil over such a small area.

In 1950-1951 the first State standard for rose oil was issued:

 In the period 1950-1954 the quantities of rose oil produced were as follows:

 Before it was closed down at the end of 1954, the State company Bulgarska Rosa - Sofia used the out-of-season period to upgrade the equipment and the technology and to promote new articles for the perfume and pharmaceutical industries in the following directions:

 

• Distilleries in the Rose Valley gradually consolidated and those of lower capacity and technically less sophisticated were closed down.
• New, regional installations with steam distilleries for processing of floral and grass raw stuff were set up
• The equipment was also modified. A new still of 5000 liters capacity was introduced. It had a replaceable cover using a basket or fenders to carry the grass raw stuff. The equipment worked with an electric hoist.

A unified Florentine system was introduced: one Florentine flask in a separate Florentine premise collected the attar from all stills and the cohobated oil was gathered in a separate Florentine flask. After that, during the distillation of rose flowers, the raw and the cohobated oil (oil that had been subjected to multiple distillation) were collected in a common Florentine flask.

Since 1960, continuous action cohobators came to be installed in all new distilleries. The rate of rose and lavender distillation increased almost twofold, from 5% to 10%. This improved the yield of rose oil and increased the percentage of esters in the lavender oil.

On November 13, 1954, a Decree of the Council of Ministers set up the Bilkoop department with the Central Cooperative Union. It was intended to manage gathering, cultivation and processing of herbs, as well as the manufacture of essential oils. A Decree of January 6, 1960 placed the manufacture of essential oils and all distillery installations under the Chimimport State Trading Company. The Bulgarska Rosa Directorate was formed with the Chimimport Company. It controlled four enterprises of the name Bulgarska Rosa in the towns of Plovdiv, Karlovo, Kazanlak and Gorna Oryahovitsa.

The newly-formed Directorate with Chimimport concerted its efforts on preserving and expanding the areas planted with roses, peppermint and lavender. The annual output at that time tended towards 1100 kg. Big installations regained importance and new ones were built each of them comprising a 5-tonne universal still, a continuous action cohobator and a unified system. Experiments were conducted, mainly aimed to find better ways of storing the rose flowers before distillation.

A Bulletin on Essential Oil Industry Promotion" used to come out in the period 1962 - 1973. In 1964, during the rose distillation campaign, in Plovdiv was held the Third International Congress on Essential Oils.

After the production and trade in essential oils together with the aromatic industry were placed under the Pharmachim Company in 1965, the following quantities of essential oils were produced

Rose attar is obtained today in the three enterprises of the common name of Bulgarska Rosa in the towns of Plovdiv, Kazanlak and Karlovo.

Lavender, peppermint and other essential oils, in addition to those already mentioned, are produced also in the Lavena joint-stock company in Shoumen. The enterprises are now accommodated in new, specially designed premises and use up-to-date equipment. All of them work on a round-the-year basis. In addition to essential oils, they started manufacturing products for the perfumery and cosmetics, pharmaceuticals and other medical products. Stilling of gyul rakia (gyulovitsa, or rose brandy) was revived.

The Bulgarian rose production is popularized every year during the Festival of Roses. The festival originates from the celebrations held at the beginning of the rose-harvesting period. Old rose growers used to organize pageantries in which manufacturers paraded, dressed up in rose flowers.

The first official Festival of Roses took place in 1903. The visitors could attend exhibitions of various rose species and other flowers, buy postcards featuring views from the Rose Valley or go on excursions to the Shipka Monastery. The funds raised were given out to poor families. In 1906 similar celebrations were organized in Karlovo.

The first celebration on a national scale was held in Pavel Banya on June 4, 1967. Manufacturers from the settlements in the Toundzha river valley, singing and dancing, together with the masked dancers, called koukeri, contributed to the festive atmosphere. The celebrations became traditional in Kazanlak and later on in Karlovo too. The rose festivals are usually held in the first Sunday of June as this is the time when roses are sure to be flowering and because it is the harvesting period...

The Festival of Roses can be viewed as a tribute that is paid to beauty every year. The rose industry has long ago transcended its primary importance as a means of sustenance for the people living in the Rose Valley. It has become for them a way of approaching Nature.

For a period of 330 years Bulgaria won recognition as the country of roses and the rose flower has rightfully become one of its symbols.

The Valley of Roses has at all times amazed people with its beauty. The great Bulgarian writer Ivan Vazov gave vent to his emotions which the lush landscape of the Rose Valley evoked in him back in 1886, but his description of the Rose Valley is valid until the present day:

"How beautiful this valley is! As far as eyes can see, glistening green meads and tender velvety swards, rose gardens in blossoms spelling fragrance, clear mountain springs murmuring through fresh meadows, tufts of chestnuts, walnuts, plum-trees, cherries, cornel-trees and apples in flowers and across this wonderful green panorama, among copses of willows and whispering elms, the young Toundzha meanders in wonderful curves. At the background one can see Stara Planina: a range of giant peaks, basking in the blue sky... And fifteen days later, some enchantress will sprinkle dewy roses upon these tender greens and the air will be flooded by this fragrance and by the songs of the dark-eyed women rose-harvesters with freshly-picked rose flowers on their heads..."