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Greenhouse vegetable varieties

Gewächshaus Gemüse Sorten

Now that your tomatoes, peppers, melons and cucumbers are planted, you should check to make sure that the cultivated varieties were all correct. What was the yield and taste? Were there any issues? For example, high rainfall in some areas this year resulted in high humidity levels, which could in turn effect your plants in the greenhouse. When planning or selecting plants for the next year, you should always make sure that the varieties chosen are suitable for your particular greenhouse. When buying young plants in a garden center, it can be difficult buy such varieties.

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Vegetable Sowing and Propagation – Professional Tips and Techniques

Gemüse Aussaat

The time for the first sowings aproaches. Each year brings a new beginning. But what if things don't work out? Seeds are rarely the cause, provided you have not used ancient seeds. You can easily check this by first conducting a seed test on household paper! Seeds are normally quality controlled and must meet certain strict criteria. In any case, for a seed to successful germinate, it always require four things: moisture, heat, oxygen and soil.

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Planting roses – tips and tricks

Rosen pflanzen

Roses belong to every garden, but they should especially not be forgotten on the terrace and balcony, where they truly shine. The beauties need a lot of light and a breezy location, to ensure that the leaves dry quickly after a rain. In this way, roses can stay more resistant to fungal diseases. Roses are among some of the oldest crops planted by humans. There are even Confucius reports of rose plantings in the royal gardens in Beijing.

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Orchid care – the best tips and tricks!

orchid care

Orchids, especially the Phalaenopsis, today belong to the category of "normal" houseplants. But the title is somewhat misleading, because many were first optimised in greenhouse settings.

The long lifespan of flowers, their various and bizarre forms, their exotic colours, are in short, the beauty of over 30,000 different varieties of orchids worldwide and is a special fascination for many people worldwide. Whether miniatures or giants, orchids provide a world of diversity for everyone.

The different origins of various orchids allows for their care in not only cold, but also tempered and warm greenhouses too. Even unheated greenhouses can be used for “frost hardy” specimens. The variety certainly makes for a exciting hobby.

In a greenhouse, it is possible to cultivate orchids not only in a pot but also in a seemingly natural environment. It is also possible to establish a variety of orchids in a small space since miniature forms of orchids are commonplace and can be used to maximise small spaces. 

Where do orchids come from?

Orchids grow on all continents, especially in tropical areas. In addition to natural forms, other breeds have emerged, including numerous genera (the plural of genus) and even multiple category hybrids. The location or origin of a particular genus gives an indication as to the correct temperature or environment for it, as well as any required rest periods.

Orchids with bulbs (light onions – pseudobulbs), for example, need a rest period as they adapt to the changing seasons. This is quite similar to Slipper Orchids (Cypripedium), which lose their leaves in autumn and winter to the soil beneath. Their tropical relatives behave similarly, they either lose their leaves (Lycaste) or stop growing. Only bulb-less orchids, such as the Moth Orchid (Phalaenopsis) or Venus Slipper (Paphiopedilum), know no proper rest. They do not need it because their conditions are quite stable throughout the year. Generally, a rest period begins once a set of sprouts have finished growing and ends with the growth of new shoots.

Watering and feeding orchids

The correct amount of water and fertiliser depends on the growth stage of the plant, the current season and the individual condition of the plant. Bear in mind though, that the orchids do not easily show if they need water or not. Their mostly firm, almost succulent, leaves and bulbs rarely give the orchid a “limp” feeling. One can only determine whether the plant is still sufficiently moist, based on whether or not healthy roots are present and whether the plant is still growing at all.

Only in the growing season do orchids need water (and nutrients). With a quick finger test, you can tell if they require water: To do this, push your finger lightly into the earth. If the substrate feels cold and wet, then it doesn’t require any water and it’s as simple as that! Many orchid care problems arise due to improper watering. Too much water, too little, too often, too rarely. Oftentimes this can cause root damage, which can even lead to the complete loss of a plant.

Preferably, use soft, still water at room temperature. However, if you see twisted leaves, this can often indicates some damage to the roots. As mentioned, the reason is usually over-watering, but it can also be the result of not enough humidity. As a rule of thumb with orchids: Better too dry than too wet!


Orchids want to grow high

In the case of tropical orchids, the epiphytes, literally translated as “overgrowing plants” are the predominant variety. The epiphytes derive their nutrition from small amounts of top soil. But it is not only orchids, ferns, bromeliads and many other plants grow in the same manner. Interestingly, epiphytes make up 30 to 50 percent of the total flora in some tropical forests. They are characterised by high adaptability to their environment.

Orchids also have a special root, the aerial root. This allows them to “absorb” water and nutrients very quickly. This is particularly important when it comes to absorbing tropical rain and dew.

Orchids in the greenhouse


Light and shadows

Orchids have different lighting requirements according to their origin. In indoor settings, plants with lower light requirements are able to survive. However, a lack of light can be recognised by yellow, soft leaves. A seasoned-gardener would refer to this as “etiolation”. Quite different are the possibilities seen in a typical greenhouse, where plants must be in shade from May to September. Without light, plants can not process water or nutrients.


Bottled fertiliser and nutrients

Plants need a lot more fertiliser in the growing season – usually during the light-rich spring and summer seasons – compared to when they are not growing. Don’t forget that they also need some fertiliser in modern substrates! As a rule of thumb, you should remember to fertilise with every third watering. But do not fertilise dry plants – this poses the risk of burning the roots. Normal fertilisers are usually too nutrient-rich for orchids, the ratio of nitrogen to phosphorus and potassium is not right and some important trace elements are missing. Rather than aiding it, this can seriously injure the plant. The remedy for this problem is an individual fertiliser that is tailored to the needs of orchids.


Repotting and substrates

Depending on the growth cycle, orchids are usually implemented annually or only in 2-3 year cycles. You should always use special earth for repotting. This is because the epiphytic ‘lifestyle’ requires a particularly permeable, yet structurally stable substrate. Today, cocci are heavily used as fibre and chips, peat moss (sphagnum) and bark.


How to combat pests on your orchids

As with most plants, it is important to pay attention to pests, however orchids in particular, require special attention. Spider mites, the red spider, woolly and scale lice are all likely pests for your orchids and they can attack fairly often. Corrective measures in the greenhouse can involve beneficial organisms or various approved plant protection products.


The original version of this article was published in the Greenhouse Post, issue 12/2015, text and image: Jörn Pinske.

Plant your own lettuce

lettuce plants

The gardening year starts with lettuce … and ends with lettuce. Not just in the field, but also in greenhouses and cold frames. Lettuce is a collective name for mostly fresh and prepared leaves of various plants.

When one hears mention of a garden salad, one thinks immediately of lettuce. From March until Autumn, you can sow the required amount of lettuce every 14 days. Of course, the differences in each of the varieties should be taken into account. The first plants should be purchased in February from a garden centre. There, they have more light during the germination stage and are thus more stable than when bred in a room. From the end of February you can then plant them in a cold frame or in an unheated greenhouse. They are set in reasonably dense arrangements, 20 cm X 20 cm arrays are best for most varieties of lettuce.

Early in the year you should also use a black mulch foil, as it helps to keep heat and moisture in the ground. Young plants are usually first cultivated in peat pots. Lettuce must never be planted too deep, otherwise head formation will be delayed and fungal diseases will occur more frequently. Airing is hardly necessary, as the water requirement for most lettuce varieties is low. However, from 18 ° C upwards, your plants should be well-ventilated. Initially, it will take a short time for air exchange, but even cold outside air will not hurt these sturdy plants. Once the plants are firmly rooted, even night time frosts will not cause any problems.

lettuce plant heating

Paraffin can be used as a great source of protection against the cold in the first few days, by heating the greenhouse directly over the plants. The Green Guard mini-gas heater also offers protection in spring, the energy consumption of this device is low and plant growth is accelerated enormously. Also to note: lettuce, like many plants, should not be initially kept too wet or else it will have problems developing enough roots.


ettuce mulch foil

Black mulch film, available from Biogreen, is also a great way to keep residual heat in the ground – the foil is even biodegradable!

Where the lettuce comes from

The head of lettuce plants is created by a compressed shoot. The two main garden salad types are the well-known Butter and Iceberg varieties. Butter lettuce has rather soft leaves, whereas the Iceberg has relatively firm leaves. Between both of these, there also exists a variety known as Butter Head lettuce, which has somewhat soft, but also somewhat firm leaves. The leaves mostly plume from a delicate green to a reddish brown.

The archetype of a classic garden lettuce can also bring to mind the Prickly Lettuce variety (Lactuca serriola), which is often found as a steppe plant in southern Europe, the temperate West Asia, up to northern India and northern Africa. The breeding of each variety also causes each to develop its unique characteristics for example, the summer varieties can either be short-day plant or a day-neutral plant.

Some others are particularly heat-tolerant or resistant to lettuce aphids and / or powdery mildew. There are varieties which prefer an early start to the season and other varieties which are better suited for autumn and winter. At present over 100 different varieties are available. You will just have to try them all! This has another advantage, as you can choose a variety of species for year-round cultivation!

When it comes to lettuce culture, you should always make sure that every 2 to 3 weeks new seeds are sown. For each person, about 20 plants are recommended. Harvesting begins well before the heads are completely firm, when only the last heads are fixed, then the “new ones” begin to shoot again. From planting to harvest, it takes about 5 – 7 weeks, depending on the season.


planting lettuce

Always plant the salad quite high in the soil, otherwise the bottom leaves can quickly rot.

Salad culture

Lettuce seeds should be sown from February / March until Autumn (in the northern hemisphere). Lettuce requires low temperatures for germination, which are present during cooler nights. If the soil temperature stays above 18 to 20 ° C at night, it will either grow rather slowly or not at all. Even for certain varieties which suit warmer months, sowing may only been done in the cool hours of the evening.

After sowing, the soil temperature can be lowered by slightly watering. As soon as the first leaves of the seedlings appear, the plants should be separated. When sowing with single corn seeds in multi-pot plates you do not need to do this however. The germination duration is between 4 to 30 days, depending on the variety and temperature conditions. Only when four to five leaves have formed, should the plants be planted with bales in the field. Aim to air the plants out slightly more and more and to have them eventually planted during a cloudy day. If you do not want to wait too long, you can also cover the plants with fleece or some sort of cover. Plant all varieties in the garden in a 25 cm x 25 cm array. The varieties planted in the greenhouse and cold frame should also be planted nearby to one another.

Lettuce is fairly self-compatible, meaning that it can be planted easily in places where it has previously grown already. Only the nutrient supply must be taken care of here. However, be aware that lettuce is sensitive to salts, so mineral fertilisers can burn it easily. A low-strength liquid fertiliser, not poured over the leaves, may be best. As mentioned, lettuce must never be planted too deeply and take care that they are not over-watered and that the leaves are dry going into the nighttime.


lettuce cold beds

Just like in a greenhouse,cold frames can help you to optimise the cultivation of lettuce, from the beginning of the season, right through to Autumn.

Diseases and pests

Lettuce can easily suffer from rot, which can be avoided by ventilating the plants when they are still young. Many species of aphids can also be a problem for lettuce, yet they are easily controlled with biological means. For film culture, first remove the film before the formation of the lettuce head. All lettuces from the family of Lactuca sativa var. Capitata contain a white milk juice in their stems, which therein contains the bitter substance lactulin. You can easily see it flow out when the plant is cut. This gives the lettuce its pleasantly mild to slightly bitter taste and helps to support our digestion with its ‘stimulating’ effect.

Upon contact with air, the originally white juice at the interface turns brownish, which makes it possible to determine the freshness of the head of the lettuce. Fresh from the harvest lettuces are rich in vitamins, minerals and fibre, as well as low in calories and rich in appetising substances. Lettuce should always be cut as fresh as possible, prepared as soon as possible and eaten immediately afterwards.

Was lettuce tastier in the past?

Whether this is really the case is still somewhat contentious, however older varieties usually have larger heads with soft leaves; today, other characteristics are have been assigned more importance. Rapid growth, resistance to disease, a closed but small head which makes for easy processing – when cutting off the trunk, the head disintegrates into leaves of equal size.

The original version of this article was published in the Greenhouse Post, issue 12/2015, text and image: Jörn Pinske.

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