The underground tubers of the potato (Solanum tuberosum) are a particularly valuable staple food that is on the menu almost every day. But what about the tubers when potato plants don't develop flowers?
In a nutshell
- Blossoming initiates fruiting and tuber growth
- The tendency to bloom varies depending on the variety
- Tuber growth is controlled by a flowering hormone
- some varieties flower longer, others not at all, less or shorter
- Potatoes may not flower in whole or in part due to unfavorable conditions or incorrect care
Potatoes bloom
Potato plants form flowers from which the fruit develops. These are not the tubers, but aboveground, small, green, cherry-sized, poisonous berries containing the seeds.
Source: Ordercrazy, Solanum tuberosum Ostbote (02), Edited from Plantopedia, CC0 1.0
- the plant's own hormone controls flowering
- is influenced by temperature and day length
- with the beginning of flowering, development of the above-ground parts of the plant is largely complete
- Growth shifts from leaves to tubers
- Stolons (foothills) stop growth in length
- they develop sprout tubers (thickening)
Depending on the variety, the potato blooms between June and September. Many small tubers have already formed during the flowering of the potatoes, but they still have to increase in volume before they are fully ripe. In general, flowering is not necessary for tuber growth.
Tip: Due to the shortened growing season, early potatoes can already be harvested during the flowering period. All others only when the foliage is completely withered.
Potato blossom is gone?
Basically, the tendency to flower formation varies in the numerous potato varieties and can vary from year to year. So it can happen that not all plants develop flowers or that they are only weakly developed. Nodules usually form anyway, but remain somewhat smaller.
Blossoms play no role in the harvest of early potatoes. The situation is different for ware potatoes that are to be stored over the winter. With them, the flowering should be completed by the time of harvest and the foliage should be completely withered. However, there are also varieties that generally do not flower. The reason for this is mostly overbreeding. But diseases, pest infestation or poor cultivation conditions can also limit or prevent flowering.
Factors affecting flowering
Seasonal temperature profile
Thanks to an ingenious system, the potato plant is able to distinguish between short and longer days. It is one of the so-called long-day plants. They bloom as soon as the nights fall below a certain number of hours. When it comes to temperatures, potatoes thrive best at temperatures between 18 and 25 degrees. Temperatures above 30 degrees can affect plant growth and thus the flowering of potatoes. Consequently, they should be in the ground by May at the latest.
drought and waterlogging
The potato does not suffer from prolonged drought and waterlogging. Both inhibit the plants in their development and thus also the formation of flowers.
- Drought leads to undersupply
- Flowering may not occur or may be significantly weaker
- Makes plants more susceptible to diseases and parasites
- At worst, let them die
- Water the potatoes as a preventive measure, especially if the drought persists
- About every two to three days
When watering, the leaves should be kept dry and only watered on the root area. The water requirement is highest in the period from emergence to flowering. One speaks of emergence when the seed has germinated and the little plants become visible.
ground conditions
Ideally, soil pH is between 5.5 and 7.0 and low in salinity. At lower values it can happen that nutrients such as e.g. B. phosphorus are only available to a limited extent. Even if the pH is higher than 7.5, micronutrients and phosphorus can be limited, although the total amount of nutrients in the soil is high. In addition, the plants are then more susceptible to powdery scab. If the values are particularly high or low, the floor should be adjusted if possible. Low values can be improved by liming. However, you should lime at least six months before planting.
nutrient deficiency
As heavy feeders, potatoes withdraw significant amounts of nutrients from the soil.
Among other things, drought can be responsible for a lack of nutrients, the plants can hardly absorb phosphorus, which is responsible for tuber growth, from the soil. In addition to phosphorus, however, nitrogen and magnesium are also among the main nutrients. A deficiency shows up in the whole plant or the tubers. Deficiency symptoms are rare, however.
Tip: Potatoes should be grown in a different location each year or in the same place after four years at the earliest. During this time, the planting of medium and weak eaters is a good idea.
diseases and pests
Some diseases and pests can be responsible for severely reduced or absent flowering and develop stunted tubers. With regard to flowering, the so-called Verticillium wilt and blackleg, especially at an early stage, are particularly worth mentioning. If the plants are infested, they age prematurely and die off, preventing flowering. Potato pests usually attack the young shoots and leaves, but also the flower buds, such as black lice and mites.
frequently asked Questions
When is the flowering time for potatoes?Early potatoes show their flowers from around the end of April to the beginning of June, mid-early varieties in June and late varieties from August. Basically, the flowering period extends from June to September.
Do potatoes have to bloom?It is not uncommon for potatoes to hardly or not flower at all and in most cases has little influence on tuber growth. In the case of new potatoes, blossoms are of secondary importance; they are harvested when the leaves are still green. In the case of ware potatoes that are being stored, flowering should be complete if possible and all parts of the plant above the ground should have withered. This ensures that the tubers are ripe and therefore storable.
Why are the flowers falling off?The flowers wither relatively quickly and fall off. But that doesn't matter, because the main purpose of the potato blossom is to produce fruit and seeds. And fruits are not the tubers in the ground, but the green berries growing above ground.