- How to propagate sweet potatoes
- All propagation methods at a glance
- Overview of sweet potato varieties
- Correct location for the sweet potato
- Care for sweet potatoes
- Pests on Sweet Potatoes
- Harvesting, Storage and Curing of the Sweet Potato
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Growing sweet potatoes in the garden: We present suitable varieties of young plants and give tips on planting, care and fertilization, right through to harvesting.
As early as the 16th century, the sweet potato (Ipomea batata) conquered the European market, even before the well-known potato. However, the sweet potato remained more of an exotic vegetable and the potato became an export hit at the time. Within a very short time, the "normal" potato quickly became the most important food source in many parts of Europe. The cultivation of sweet potatoes was not pursued further. But there is actually no logical reason for this. Although the sweet potato comes from the tropical and subtropical regions of South America, with the right cultivation tricks and adapted varieties, a high harvest yield is also possible here. The sweet potato has been in vogue for a short time, which has not only arrived in the kitchen, but also in cultivation. A few years ago, field trials were carried out by the Weihenstephan-Triesdorf University of Applied Sciences. The results show that sweet potatoes can also thrive in our climatic conditions. So that you too can harvest your own sweet potatoes in the next gardening season, we have created the ultimate sweet potato growing guide for you.
How to propagate sweet potatoes
The most important basis for a promising cultivation of sweet potatoes is the right plant material. The sweet potato is usually propagated via the tuber or cuttings. Seeds are rarely used, since many sweet potato varieties can no longer produce seeds. So in theory, you could just buy a sweet potato from the grocery store and stick it in the ground. In warm temperatures, it will push roots and shoots after a while. There is only one problem: the variety of supermarket sweet potatoes is usually not known and the sweet potato purchased may not be optimally adapted to our climate. To avoid disappointment during the growing season, we therefore recommend rooted cuttings from specialist retailers. The varieties and their properties are known there.
Once you have decided on a suitable variety, you should order the cuttings as soon as possible. For a good autumn harvest, it is important that the plants are already a bit larger when they are planted in the bed. For the time on the windowsill, you should treat the young plants to a pot that is half a liter in size. You will learn later why this is important. In addition, the young plants need a lot of warmth and every ray of sunshine that spring offers. A south-facing window sill is therefore best suited. Avoid temperatures below 10 °C and cool drafts by ventilation. Because the sweet potato can already be damaged from single-digit temperatures. At temperatures around 25 °C, on the other hand, the batate feels really good. In addition, water the plants regularly so that the substrate always remains moist (not wet!). Fertilization is not necessary if pre-fertilized soil was used for repotting. The plants now remain on the window sill until the temperatures no longer drop below 10 °C at night. Young sweet potato plants are relatively expensive. For this reason, you should continue to propagate the purchased cuttings yourself. This is the only way to inexpensively create a bed of sweet potatoes.
All propagation methods at a glance
Sweet potato cuttings
A quick and easy way to get lots of small sweet potatoes is to propagate cuttings. The prerequisite for this is an existing plant with some longer shoots. Cut 10 cm long shoots from the plant. The shoots are then placed in a pot or seed tray with potting soil. Sometimes it is necessary to remove one or two of the lower leaves, otherwise the cuttings cannot be planted deep enough in the soil. To ensure that the sensitive cuttings do not dry out before they have rooted, high humidity must be ensured. You can achieve high humidity with a mini greenhouse for the windowsill, which can be had for a few euros. Now all you have to do is ensure temperatures of around 25 °C. 20 °C is enough, but the shoots root much faster at higher temperatures. Under optimal conditions, the shoots sometimes root after just 1 to 2 weeks. A sure sign of successful rooting is the beginning of shoot growth. Now the young plants should be hardened slowly: they should air more from day to day and until thefresh sweet potatoes without the plastic cover altogether.
Sweet potato tubers
Of course, the sweet potato can also be propagated via the tuber like the normal potato. So that several plants can grow from a tuber, it can be cut into several parts. Four to five tuber pieces should be obtained from a sweet potato. However, the divided tuber should not be planted directly. Allow 2 to 3 days for the interfaces to dry. This reduces the risk of rot. After the waiting time, the tuber pieces can be placed in potting soil or slightly buried. It is often asked whether the tuber should be buried completely and how around the sweet potato should be planted. Our answer: It doesn't matter! The new shoots find their way; much more important is a high temperature and the right humidity of the soil. At 20 to 25 °C and moist soil, the first shoots should be visible after a few weeks.
Overview of sweet potato varieties
As early as 5,000 years ago, the indigenous peoples of South America ate sweet potatoes. Through domestication, the natives have contributed to today's diversity of varieties. The sweet potato is now grown in almost all warm regions of the world. With around 7,000 varieties, the sweet potato offers a huge selection of different plants. Most often, the varieties differ in terms of the root tuber. There are tubers with red, yellow or white skin and the color of the flesh ranges from orange to white to purple. Even the foliage does not always have to be green. Special breeds are particularly suitable as ornamental plants because the leaves are strikingly colored. Of course, other properties also play a role. The cultivation time is particularly important for use in the home garden. Because we should only grow varieties with a short cultivation period. Unfortunately, the selection of varieties in Germany is still limited at the moment. However, this situation is likely to change quickly, because interest in the sweet potato is growing and growing. At this point we would like to introduce you to four varieties, of which young plants can also be bought. In addition, the varieties were tested by the Weihenstephan University of Applied Sciences and can all be successfully cultivated in Germany.
- Beauregard: Short-growing variety (90 - 95 days). The tuberhas a red colored skin, the flesh is orange. In the field trial, this variety formed the largest tubers and yielded 3.5 kg per m². Varieties with an orange flesh contain a lot of beta-carotene.
- Bonita: This variety also delivers a reliable yield, but the tubers are a bit smaller. The skin is pink in color and the flesh is white-yellowish. Bonita should be a real all-rounder in the kitchen.
- Evangelina: The Evangelina variety is said to taste particularly fine. Perhaps this is due to the relatively high sugar content. It is also suitable as an ornamental plant due to the wine-red shoot tips. The tuber color is red-purple and the flesh is orange. Culture duration: 100 - 110 days.
- Murasaki: The Japanese breed with white flesh and a pink skin is a real eye-catcher. With a sweet and nutty taste, the variety is said to be particularly suitable for chips. The culture lasts relatively long at 120 - 130 days. The yield is not high, but the unusual tuber color makes up for it.
Unfortunately, these sweet potato varieties are not yet available in Germany:
- Oklamex Red: The tubers have a dark red skin and salmon-colored flesh. The sugar content of this variety is said to be particularly high.
- Sumor: The vitamin C content of this variety is said to be very high. But the variety also has a lot to offer in terms of colour, because the flesh has a very nice white to yellow colour
- Black Hearth: The Black Hearth variety is more of an ornamental plant. The leaves have an intense violet color and should not be missing in any flower box. In well-stocked nurseries you can often find sweet potatoes with special leaf colors.
Correct location for the sweet potato
Growing sweet potatoes in the bed
The young plants should be planted outside at the earliest after the ice saints. If the nighttime temperatures are in the single digits, you'd better wait a little longer. A cold shock can stall sweet potato growth for a long period of time. A cold frame fleece is recommended for impatient gardeners. This protects the sensitive plants from the wind and under the fleece the temperatures are always a few degrees warmer than outdoors. In addition, the fleece initially offers protection from the sun. Because even the light-hungry sweet potato has to adapt to direct sunlightget used to first. In addition to the planting date, the location itself is of course crucial for a lush harvest:
- Prefers full sun; Partial shade is possible but not ideal
- Light, sandy soil for good tuber formation and against waterlogging
- Cultivation also possible in the greenhouse
If the days are warm enough, the young plants can move into their new home in the bed. To do this, carefully free the root ball from the pot. Now the root ball must be carefully loosened. This step is important to avoid unsightly root nodules and adhesions later on. For optimal growth, the plants should also not simply be planted in the shallow vegetable patch. When growing sweet potatoes, the dam method has proven to be particularly promising. With this technique, the sweet potato can also be successfully grown in heavy soils. For the cultivation technique, 60 cm wide and 20 cm high earth dams are created in the bed, which are at least one meter apart. The young plants are then planted on the ridges at a distance of at least 30 cm. Growing on a dam offers two major benefits. First, the soil in the dam can warm up faster, giving the sweet potato a growth advantage. In addition, excess water drains off faster and the risk of waterlogging is reduced.
The sweet potatoes grow very slowly at first and the bed offers a lot of bare soil, which should actually be avoided. That is why the sweet potato is perfect for mixed cultivation. Between the dams, crops can be grown that only need a short period of time to be harvested. You can sow lettuce, radishes or spinach there. With the mixed culture method, you prevent soil erosion and use the space in your garden much more efficiently. Now the foundation for a high yield in autumn has been laid. In addition to fertilization, location and propagation are crucial for successful sweet potato cultivation.
Pot culture of sweet potatoes
Sweet potatoes can of course also be grown in a container. It is important that the bucket holds at least 20 liters of soil (for a young plant). The bucket can be placed anywhere that is sunny. Black plastic tubs are best, because they convert the sun's rays into heat, which makes the sweet potatoes particularly cozy. A stone wallcan release the heat stored during the day over the night and thus also ensure higher temperatures. As with bed culture, a loose and well-drained substrate should be used. If you have pre-fertilized well, you do not have to add any other nutrients at first.
Care for sweet potatoes
The sweet potato does not need any special care. If the bed is properly prepared and a good location is chosen, the plant will grow by itself. Only at the beginning, when the sweet potato has not yet covered the entire bed with its creeping shoots, do weeds have to be removed from time to time. Later in the season, however, weeds can usually no longer assert themselves against the leaf masses of the sweet potato.
Water the sweet potato correctly
If the plants are still small and have few leaves, they usually hardly need to be watered. Nevertheless, you should keep in mind that the earth dams dry out faster than a normal bed. For this reason, it must always be watered when the top layer of soil has dried. When the sweet potatoes have formed a sea full of leaves in summer, water consumption also increases. If there is no precipitation and high temperatures, watering sometimes has to be done daily. Although the sweet potato tolerates short periods of drought without any problems, later tuber formation can be negatively influenced by an uneven water supply.
When growing in a pot, special attention must be paid to the water supply. When the sweet potatoes are larger, a daily check of the soil is important. This means more watering work than with bed culture. The rule here is: the smaller the pot, the more frequently it has to be watered. On really hot summer days, therefore, you can leave the water in the saucer. You should only remove excess water from the saucer in the evening. In the fall, slowly reduce the watering. The growing tubers should then not be as moist as in summer, since the tubers of the sweet potato are relatively susceptible to rot.
Fertilize sweet potatoes correctly
If you prepare the bed properly at the start of the season, no additional fertilization is necessary.
- Work 3 liters of mature compost and 100 g horn meal per m2 into the soil
- if a mixed culture is created, the nutrient consumption increases and more fertilization is required
- alternatively, you can also use primarily organic organic fertilizers such as our Plantura organicTomato fertilizer can be used
When growing in a bucket, a single fertilization is definitely not enough. Here we recommend a light weekly fertilization with a high-quality liquid fertilizer such as our Plantura organic tomato & vegetable fertilizer. Begin applying the liquid fertilizer when the sweet potato starts vigorous leaf growth.
Pests on Sweet Potatoes
Again, we have good news: the sweet potato does not seem to be particularly popular with native insect pests. No damage was observed in the large-scale field test at the Weihenstephan-Triesdorf University of Applied Sciences either. However, it has been reported by some gardeners that mice will occasionally pounce on the mature root bulbs. Only timely harvesting helps here. It is to be hoped that over time no new pests will be introduced that also target the sweet potato.
Harvesting, Storage and Curing of the Sweet Potato
The sweet potato only starts to form tubers in September. Before that, all the energy is put into sheet formation. The perfect harvest date is when the leaves turn yellowish (October). At this time, the highest content of carbohydrates is in the tubers. Depending on the variety or the weather, however, it may be that the tubers have to be harvested earlier. Because the tubers do not tolerate frost and must therefore be taken out of the bed before the first frost. Even if the weather throws a spanner in the works, the tubers will be tasty even if harvested a little earlier.
The upcoming harvest will require a little finesse. The tubers only have a very thin bark, if this is damaged, the storage time is shortened and rot can occur. Most of the time you don't have to dig deep when harvesting, because the sweet potatoes are more in the upper layer of the earth. The dug up tubers should be washed thoroughly for storage and then it is best to let the sweet potatoes dry in the sun. In principle, the sweet potatoes can be eaten straight away, but the batata initially have a high starch content and less sugar. Especially with the prevailing light conditions here, the sweet potato forms less sugar and more starch. In other words, the sweet potatoes harvested here are less sweet than those from the supermarket. With aTreatment, the so-called curing, can increase the sugar content and also extend the shelf life.
The Curing:
- Usually performed in special climate chambers (4-10 days at 30°C and 80-95% humidity).
- Due to the warm and humid climate, small wounds in the shell close and starch turns into sugar.
- At home, curing can be mimicked by wrapping the sweet potatoes in black foil.
- The foil pack is placed in the sun for 5 days during the day and in the warmest room at night.
Normally, sweet potatoes can be kept for 3 to 4 weeks after harvest at 12 to 16 °C. Temperatures below 10 degrees can cause cold damage and temperatures above 16 °C shorten the shelf life. With the imitation curing, the shelf life can be extended by a few weeks. Even by many months thanks to the professional curing. Shelf life is also increased if there is high humidity in the storage room. In any case, only he althy tubers should be stored. Tubers with larger injuries are at too great a risk of spreading rot.
If you are planning to start growing potatoes in pots, here are some additional helpful tips.