When growing tomatoes outdoors, we have to bend to the laws of nature, because their sensitivity to cold only allows annual cultivation. In their sun-drenched, warm habitats, however, tomato plants thrive as perennials, as there are no limits to their growth due to frost and lack of light. The desire for several years of cultivation is within reach, provided that the appropriate framework conditions are created in winter. These instructions explain in detail how to properly overwinter tomatoes.
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Tomatoes are perennial – they are not winter hardy
In their natural range, tomatoes have the ideal climate to deliver a rich harvest over several years. The sun-drenched habitats of South and Central America, where temperatures rarely drop below 15 degrees Celsius, even in winter, are decisive for the multi-year growth. If the light and temperature conditions are in the right ratio, tomato plants prove to be tolerant of other growth factors. In order to overwinter the tropical and subtropical perennials in Central Europe, the focus is on the two bottlenecks, lack of light and cold.
Variety selection sets the course
Bringing a sophisticated, majestic beefsteak tomato unscathed to the Central European winter is doomed to failure. In order to provide a sufficient amount of light and heat, an energy consumption is required that is not in a reasonable relationship to the yield. If, on the other hand, robust wild tomatoes or dwarf varieties come into play, the cost-benefit gap closes in favor of horticultural experimentation. To overwinter tomato plants, therefore, the following types and varieties come into consideration:
Wild tomatoes with the potential to overwinter
The following wild tomatoes have retained their native vigor, which is lost in most hybrids. The plants branch out into stable shrubs and mostly bear their small fruits in dense clusters on stable, fan-shaped shoots.
Red marble (Solanum pimpinellifolium)
The historic wild tomato from the Andes is extremely strong, so that it can withstand the rigors of winter. At harvest time, she brings the gardener numerous red tomatoes with a diameter of 1.5 cm, which inspire with a mild, spicy aroma.
Humboldtii (Solanum pimpinellifolium)
This wild tomato is just as vigorous as the red marble and is bursting with health. In summer she invests her energy in countless cherry-sized tomatoes and a robust resistance to the dreaded brown rot. In winter, the reduced light and temperature conditions do not bother her as long as they are within tolerable limits.
Bolivian fruit tomato (Solanum pimpinellifolium)
This game species already proves its tolerance to the cold during the season. Until the first frost it reliably carries small, yellow tomatoes on its fan-shaped shoots. Tomato lovers benefit from this robust constitution if they want to overwinter the plants.
Dwarf tomato varieties for perennial cultivation
The following tomato plants have a decisive advantage that is essential for wintering. With their small size, they are perfect for the pot and therefore have the necessary mobility to give them away before winter.
This tomato variety remains at a height of a maximum of 30 cm, so that it is perfect for the pot and is satisfied with little space. In late summer and autumn, Tiny Tim gives her gardener a harvest of 2 cm cherry tomatoes that children also like to grab.
This compact bush tomato is very popular with home gardeners who cannot do without fresh tomatoes from their own cultivation even without a garden. On the smallest balcony or on the bright windowsill, the dwarf tomato gives its best in the form of sweet cocktail tomatoes. Thanks to their height of 20 to 30 cm, Red Robin quickly finds suitable winter quarters for perennial cultivation.
Are you still 30 cm too tall? Then this mini tomato is the perfect alternative. With a height of 10 to 12 cm and a bushy habit, this tomato plant will stay true to you for several years, provided that it is overwintered as recommended in these instructions.
Grant in good time – you should pay attention to that
Although different types of tomatoes can withstand temperatures between 5 and 0 degrees Celsius for a short time, they emerge weakened from this cold phase. Tomato plants should be cleared in good time so that wintering goes as desired. The temperatures during the day are not decisive, because in golden October they can climb up to 25 degrees Celsius.
At night, however, the thermometer drops to freezing point. By installing a minimum-maximum thermometer near the plants, you can tell when autumn is the right time to winterize tomatoes. If the device shows a nighttime minimum temperature of 12 degrees Celsius, the starting signal is given for the wintering program.
Hibernate on the windowsill – this is how it works
So that tomato plants bloom and fruit again next year, they should be given the opportunity to rest in winter. This is achieved with a combination of lots of light and cool temperatures. The following strategy has proven itself in practice:
- Shorten all shoots by about half before storing them
- Remove dead leaves
- Put the pot in a light spot with 10 to 12 degrees Celsius
- Do not use fertilizer from October to March
- Pour little so that the substrate remains slightly moist in the core
The light to sunny window sill in the slightly tempered bedroom or another, less heated room is suitable for winter quarters for tomato plants.
Greenhouse and winter garden – perfect as winter quarters
In the light-flooded greenhouse or winter garden, tomato plants find adequate conditions in winter to continue to bloom and fruit. Under the following light and temperature conditions, with appropriate horticultural efforts, there are good prospects of overwintering wild, dwarf and even stake tomatoes and harvesting fresh tomatoes at the same time. This is how it works:
- Only allow healthy, vital tomato plants in autumn
- Place in a light to sunny spot in the greenhouse or conservatory
- Temperatures between 16 and 22 degrees Celsius
- Continue pouring when the substrate dries on the surface
- Potassium-emphasized fertilization in half the concentration
- Manually pollinate flowers by shaking the shoots
The supply of water and nutrients requires a sure instinct in horticulture if tomato plants are to continue to bloom and produce fruit in winter. The dosage should be individually tailored to each plant and should generally be below the summer quantum. In particular, avoid nitrogen-stressed fertilization, as this nutrient leads to increased growth under winter conditions.
Bottleneck lack of light – this is how you solve the problem
Cloudy winter weather inevitably leads to a lack of light on the windowsill as well as in the greenhouse and winter garden. The higher the temperatures at the location, the more light is required for tomato plants to survive the winter healthy and happy. In a cool winter, at least 1,500 lux are required. From 15 degrees Celsius, the requirement increases to 2,000 to 3,000 lux. The following options for increasing the amount of light are available to you:
- Place a mirror on the windowsill or a wooden board covered with aluminum foil behind the plant
- If there is a permanent lack of light, install a plant lamp
- Hang the special lamp 80 cm above a tomato plant
- Illumination duration of at least 8 to 10 hours in the absence of any daylight
An inexpensive lux meter or a lux meter app will tell you how bright your tomatoes are in winter. Please note that plant lamps shine with a blue-red light spectrum, so they are not suitable for illuminating living spaces. At the same time, this light spectrum stimulates growth, so that the need for water and fertilizer increases.
The annual cultivation of tomatoes in our regions is based solely on their sensitivity to frost. In their South and Central American areas of distribution, tomato plants thrive as perennial perennials, as there are no limits to their growth there due to frost and lack of light. Lovers of the crunchy paradise apples use this property to overwinter and care for tomatoes for several years. Wild and dwarf tomatoes offer the best prospects for a successful course. The plants rest on the bright windowsill at 10 to 12 degrees Celsius until the beginning of the next season. Alternatively, a light-flooded greenhouse or the winter garden offer the option of a bright winter time at 15 to 22 degrees Celsius, in order to harvest fresh tomatoes all year round.