Except for a few overbred potato varieties that don’t flower, the flowering phase is part of the normal ripening process of the potato plant. After fertilization by insects, tomato-like fruits develop with seeds, but these are not used for horticultural and commercial potato cultivation. If the potatoes do not bloom, this can have different causes, ranging from care errors to illness.
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With the help of special messenger substances in the leaves, potato plants are able to measure the length of the day. Once certain conditions are met, the plant begins to form flowers. By this point in time, many small nodules have already formed below the surface of the earth, but they will have to increase in size over the next few weeks. The individual potato varieties differ significantly in their growth behavior. New potatoes are among the long-day plants whose flowering is stimulated when the days get longer. Late-maturing strains wait until fall, when the days are getting shorter, to produce bulbs and flowers.
- early potato varieties: ripening time 90 – 120 days, flowering time from the end of April to the beginning of June
- medium early potatoes: ripening time 120 – 150 days, flowering time from June
- late potato varieties: ripening time 150 – 180 days, flowering time from the end of August
Reasons for the lack of flowering
Normally, the flowering of the potato is a sure sign that the tubers are also beginning to grow in the soil. Potatoes not blooming can have a variety of causes.
1. Care mistakes
Although potato plants are not particularly difficult to cultivate, unfavorable conditions can still arise during cultivation. These care mistakes can also cause the lack of flowering.
Drought
Because of their limited root growth, potatoes depend on a steady supply of water. Insufficient water intake, for example in the case of prolonged drought, leads to undersupply. If you forget to water during this time, you not only prevent flowering, but also risk the plant dying.
- water regularly during dry periods
- especially just before and during flowering
- water as close to the ground as possible
Lack of nutrients
Potatoes are heavy feeders and therefore need soil with a high nutrient content. If this is too low, it doesn’t matter much at the beginning of the growth phase. However, from the moment just before ripening, the potato needs a lot of strength and energy for the formation of tubers and blossoms. If there is a lack of nutrients, the plant is unable to adequately develop new plant tissue and thus produce flowers and potato tubers.
- fertilize with manure in autumn before planting
- alternatively spread a green manure
- incorporate rotted compost into the soil in spring
Unfavorable soil conditions
Potatoes prefer loose, humus-rich and nutrient-rich garden soil that should be as free as possible from weeds. Anyone who has planted their seed potatoes in very heavy or sandy soil will be at a disadvantage after the first growth phase at the latest. A lack of water or waterlogging severely inhibits the development of the potato plant, which can lead to difficulties in ripening. Improvement measures are hardly possible after planting.
- Loosen the soil carefully with a rake
- Do not injure tubers and roots
- incorporate compost when piling up
- possibly mix in sand
- Be sure to keep weeds away
2. weather conditions
Potatoes thrive particularly well at temperatures between 18 and 25 degrees. Outside of this comfort zone, plant metabolism and growth change drastically. At temperatures above 30 degrees, kindling or chain formation occurs on the tubers. Depending on the seasonal temperature profile, flowering can then either occur much earlier or not occur at all.
- ensure good ventilation
- thin out the rows if necessary
- possibly shade
3. Diseases
In addition to a care mistake, a number of diseases can also be the reason why the potatoes do not want to bloom. Therefore, examine the plants regularly.
late blight
Late blight is a disease caused by fungal pathogens. The fungus overwinters in potato tubers that have already been infected by the spores in spring or summer. From here the fungus grows up the stalk of the potato plant in spring.
Damage
In damp weather, yellowish-green spots appear on the leaves, which soon turn dark. If you take a closer look at the underside of the leaf, you can see a whitish layer of fungi on the border between dead and healthy tissue. When the weather is dry, the fungus lawn disappears again. Infested potato tubers show irregular gray spots that can also cover whole parts of the tubers. Below these spots, the tissue is discolored brown.
Measures
Systemic fungicides are available to combat late blight, but they should not be used in the home garden. Remove the largest foci of disease. It may be necessary to thin out the rows so that the potato leaves can dry out more quickly. Harvest potatoes only when they already have firm skins. From now on you should only plant resistant varieties.
Verticillium-Which
In dry, hot summers, the wilt disease in potatoes causes high crop failures – and often also a lack of flowering. The pathogens are also fungi, which are widespread and occur almost everywhere.Damage What often looks like harmless dry damage to the leaves of the potato plant can also be caused by a harmful fungus. On the plants, the leaves turn yellow from the tip. They curl up, wither and then dry up. In most cases, however, only individual shoots are affected. Since Verticillium wilt is primarily noticeable in fully developed plants shortly before flowering, the potato will then no longer flower.
Measures
The fungi cannot survive very long in the soil, so sensible crop rotation is the best measure against wilt disease. If the potato plants are nevertheless infested, individual, severely damaged plants can be removed. Careful weed control is also important.
4. Pests
In addition to the well-known Colorado potato beetle , which eats the leaves of the plant bare, there are other pests in potatoes. These can weaken the plant to such an extent that the flowers die or do not form at all.
- Colorado potato beetle and its larvae
- other pests: aphids such as the peach aphid, potato aphid or buckthorn aphid
While Colorado potato beetles are best collected, various home remedies for injecting lice are suitable. This includes, for example, neem oil or soapy water.
Conclusion
If potatoes do not bloom, there are a number of possible causes: overbreeding, care errors, pests or even diseases. Although flowering is not absolutely necessary in order to be able to harvest potatoes, the lack of flowering is often caused by insufficient tuber formation. Therefore, it is important to find out the reason and to do something about the grievance.