Once the freesias have flowered, the tubers start to grow intensively. At this time, the temperature in the greenhouses may be higher, between 20 and 25 °C. Watering is infrequent and sparse and should be stopped 3-4 weeks after flowering.
The yield and quality of the tubers depend very much on the time of cultivation. They are at their largest in winter, when their peak growth period is in spring. In September-February, tubers do not grow as much in a month as they do in a week in April or May.
The tubers shall be dug when at least two-thirds of the leaves have wilted. They are dried in the greenhouse for two or three days, after which they are cleaned, sorted and treated with water. During this time they must be protected from direct sunlight.
They shall be stored in boxes with a dense net bottom.
The size of the tubers varies widely. Some varieties are large (more than 3 cm in diameter). In the same area, tubers with a diameter of 1,2-1,5 cm can be found. The diameter of the children is between 0,5 and 1,5 cm.
It has been observed that the larger corms produce larger plants, earlier flowering and more flowers at the same time.
The multiplication rate of tubers is highly dependent on their size and on the time of cultivation. In many cases, the reproductive rate of extra tubers was double and even triple that of type III, although the weight of extra tubers increased more than that of extra tubers.
It is not economically viable to grow freesias from seed, as the turnover and harvesting periods of seed freesias are longer, the labour costs are higher and their ornamental value is lower than that of tuberous propagation. Almost all recent varieties of freesia are sterile and do not set seed. The oldest varieties of freesia that do set seed are small-flowered. Such freesias are not worth growing as they do not match the beauty of the varieties that have been developed in recent decades.
Freesia breeding is quite difficult because, without artificial crossing and selection, seed populations degenerate very quickly, with a deterioration in flower colour, a predominance of dull yellowish and bluish colours, and a shattering of the flowers.
However, there are some reasons why it may be worthwhile to grow freesias from seed. Seeds do not transmit viral diseases, while fungal diseases are only contracted when the pathogens are present in the soil, and these diseases are very damaging to vegetatively reproducing freesias.
For this reason, only seed-grown freesias are grown in England. This method of propagation is widespread in Germany and Poland. Italy has a long tradition of growing seed freesias. This country exports a large number of seed freesias. In the Netherlands, freesia is the most exported plant, but here it is propagated only vegetatively. In the Netherlands, plant protection is well organised on the flower farms.
At the moment, we are not yet in a position to promote the propagation of freesias by seed, because there is no good seed available. However, this is only temporary, so we will discuss below how to grow freesias from seed.
Breeders are now working hard to develop new seed varieties of freesia.
Parigo LTD in England, M.C. van Staaveren in Holland. In Germany, a race of superfreesias is being developed. Enzett Citrin, Enzett Brunstein, Enzett Almadin, Enzett Hamatit and other varieties have recently been developed.
The newest and very good seed-bearing Diploid varieties are Biermans King Size, Mahy’s Super Giant, Van Staaveren Rainbow, Wulfinghoff Super. Tetraploid varieties are Bierman’s Discovery, Parigo Supreme, Super Emeraude, Van Staaveren Royals, Wulfinghoff, Fantastica.
The most important thing is to keep removing poorly growing, deformed, yellowing plants and those severely affected by viral diseases. Failure to do so, and in particular to remove virus-infected plants, will result in the rapid degeneration of varieties.
Harvesting and storage
Freesias are harvested for sale when the lower blossom has acquired the colour characteristic of the variety. When the florets are not very firm, it is necessary to wait for the second flower to open. If the plants are picked too early, the flowers do not hold water well. Freesias are best picked on sunny days. Pick until the next inflorescence starts. Do not pick the leaves. Soak the tools in a disinfectant solution.
Freesias keep well for about a week even in a very warm room, about 2 weeks in a cool room.
In winter, it is very common for the inflorescences not to open completely. It is better to soak them in an aqueous solution of 6 % sugar instead of water.
After sorting, the plants are tied in bundles of 20. Bind at the inflorescence and at the base of the stem, stiffly, to prevent the inflorescence from distorting.