Cultivation of biennials on the example of pansy (Viola × wittrockiana) 1. Definition and significance of biennials

The horticultural importance of biennials is that they can ornate beddings, balconies and pots due to their cold tolerance, when the frost susceptible annuals are not able to do it (freezing): in autumn and spring. The general public buys transplants already in autumn, but out of public places they are planted only in exposed places in autumn, for the most part only in early spring. In Hungary 6-7 million biennials are sold per a year, much part of them is planted into graveyards. There are short- and long-season species. Short-season ones are botanically annuals, but their growing period is shifted. In Hungary 95 % of the applied biennials belong to this group, so the cultivation is presented on the example of them. The long-season species are biennials botanically, too. In the first year they develop vegetative organs, then after jarovization, they bloom in the next year.

Flower bed with Bellis perennis 6.8.2. Growing pansy transplants

Pansy is a short-season biennial ornamental plant propagated by seed. It is an important culture around the world; its breeding is gone on intensively in these days, too. Beyond new color combinations the new varieties have better winter hardiness, heat tolerance and earliness compared to ancestries. F1 hybrid varieties are the most famous, but standard and the so called synthetic hybrid varieties are also circulated. Varieties are grouped according to growing size (low: 15-18 cm, medium: 18-25 cm), blooming date (early: in autumn and early spring, late: in April), flower size (small or multiflora: 2-3 cm, medium: 5-6 cm, big: 6-8 cm, large: 8-10 cm), and purity and combination of colors (clear, blotched, faced, mixed, stripy and banded).

Pansy has big seeds: its weight of one thousand kernels is 3 g. In the case of autumn sale sowing has to be done in summer with the use of sterile soil mixture (June-July) into flat (traditional way) or cell trays by precision seeding (modern way). Pansy needs 18 °C for germination. If the temperature rises above that it becomes halting. In summer it is difficult to provide this low temperature, therefore traditionally the growers take the sowing into cellars or cold premises, or – similar to annuals – they buy in germination-room pre-grown seedlings. The sprouting takes 7-14 days, after that seedlings demand light. By this time they may be set to outdoors under shade house with regular misting. Potting may be

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done after the emergence of true leaves into 7×7 cm or (if it is required) 9×9 cm square pots. Towards the satisfactory root development phosphorus demand of plant has to be provided. Pansy is salt-sensitive, it may be irrigated with nutrient solution of low (0.1-0.15 %) concentration. It is sensitive also to waterlogging: the ground has to be made even in open field. The first flowers come out in mid-September. The autumn sale starts in this time and takes to late October.

Pansies in pots

Pansy transplants before sale (in Autumn)

In the case of spring sale the sowing may be done later (till late October). Temperature of 18 °C can be provided in greenhouse by heating. Seedlings may elongate in poor light conditions, therefore after

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planting application of Alar 85 growth retardant in 3g·l^-1 concentration is advisable on two occasions.

The full-grown transplants are overwintered on low temperature then they are forced in early March before bedding. They are bedded out to public places in spring, because they are intolerant of trampling (they are out of sight under the blanket of snow) and salt. It is practical to plant them in autumn only in raised beddings or farer from the traffic. Those transplants, which were not able to sold in autumn, may be also overwintered, and tried to sell again in spring.

Recently, the little flowered and bushy so called cornuta type pansy spreads more and more. This group regenerates better after environmental damages. However, it has small flowers, they turn out in force therefore this type is better to public places compared to those hybrids, which have big or rather large flowers. The greater flowers has a pansy, Hungarian people still likes the better. The aim is the reshaping of community standards. Within this group came out the trailing pansies with small flowers, they can be planted into hanging baskets, too.

Cornuta pansies 6.8.3. Plant propagation

Pythium, downy mildew, powdery mildew and fungi that cause leaf spot may occur during the cultivation. The chemical control is possible against them. Out of pests, leaf chewing caterpillars and aphids may damage.

6.8.4. Other species

Lately, the unexciting bedding-outs are tried to vary fortunately by other species. Blue, white and pink varieties of Myosotis sylvatica (forget-me-not), simple and double-flowered varieties of Bellis perennis (English daisy) and the Erysimum cheirii and Erysimum × allionii with different yellow tinges have occurred.

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Flower bed with forget-me-not (Myosotis)

Erysimum cheirii

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159 Erysimum x allionii

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In case of plant cultivation in soil, the following things can cause problems among others: the infectious diseases (for example pathogens, which infects from the soil – Pythium, Rhizoctonia, Fusarium etc. -, from pests, primarily the root knot nematodes), the deteriorated or inappropriate quality soil and the unfavourable environmental impact of the chemical and physical soil disinfection. It was and it is still needed to use more effective growing methods also economically and also environmentally because of the rising price of the energy, the increasing competition, the effort for the higher yield and because of the stricter regulations. The hydroculture systems (there are several types) offer possible solutions for the soil free cultures. But what do we mean under „hydroculture‟?

8.1. Definition, grouping

In this technology, the cultivation is isolated from the natural soil, in different (mostly artificially produced) media, using solutions, which contains the needed nutrients for the plants‟ development; in case of the major ornamental plant cultures (for example: gerbera, rose, carnation) basically under some kind of plant growing structure, practically under glasshouse.

The word „hydroculture‟ covers several, from each other considerably different growing method. The basic of the grouping, among others are the type of the used medium, how the plants (exactly the roots) situated, the medium containing pots, the utilization of the nutrient solution and the ways of application.

The types of the soilless cultivation systems can be summarized according to the table below.

Soilless growing methods (Göhler and Molitor, 2002, modified) 1. substrate growing

2. mediumless growing 2.1.hydroponics (tank culture, pool growing) 2.2. NFT (Nutrient Film Technology)

2.3. PPH (Plant Plane Hydroponic) 2.4. aeroponics (air- or mist culture)

Open and closed hydroculture systems can be distinguished based on the supply and consumption of nutrient solution. In the first case, the needless solution drains over (mostly directly to the soil, and it helps neither, if the plants grown in a lifted bed, hill, container or stone wool slab). Closed hydroculture is nearly obligate in Western Europe, but also spread in Hungary. In this case the overflow is collected