Planting sweet potato is as easy as sticking a stem in the ground, but if you want to know all about how to do the perfect planting. Keep on reading…
What is sweet potato
Sweet potato is an easy to grow tropical perennial (a plant that stays alive for more than 1 year) root crop that grows as a non-climbing crawling vine. The plant forms an edible tuber underground which is a storage root used to survive the dry season, but the leaves and tops of the sweet potato plant can also be eaten.
Sweet potato (Ipomoea batatas) is part of the Morning Glory (convolvulacea) family. Plants such as Chinese water spinach (kangkong) and bindweed
There are hundreds of different varieties of sweet potato. Ranging from different colors, different shaped leaves, growth speed, and resilience to pests and drought, as well as shape and size of the tuber.
Generally the purple, red, and orange colored sweet potatoes are the most popular as they are high in anti-oxidants and vitamin A.
How to plant sweet potato
Sweet potato can be easily planted from stem cuttings also called slips.
These cuttings should be around 10 to 30 cm long and have at least 4 nodes, but its recommended to use 30 cm cuttings with 8 nodes.
The lower leaves of the cuttings need to be cut off, not pulled off or else it will damage the nodes. Only the uppermost 2 leaves and the growth tip must remain.
The cuttings should be planted as soon as possible by simply digging the cutting into the soil, leaving the growth tip sticking out.
In general its recommended to have at least 2 to 4 nodes in the soil.
If you need to store the cuttings before planting then store them in the shade, either in a bucket of water or a wet cloth, just make sure the growth tip is not submerged.
The best time for planting sweet potato is early rainy season, but they can be planted all the way up to mid and early-late rainy season.
The cuttings need regular rainfall to start growing roots. Without regular rains they will dry out and die.
It is best to plant sweet potato when a rain is expected that same day or the next day.
It is better to plant on a cloudy day or later in the afternoon when the sun is weaker so there is less chance if the cuttings drying up.
Some people distinguish between 2 types of cuttings. Those with roots and those without roots, but practically there is no difference between them and they are planted in the same way. Cuttings with very long roots are more prone to their roots breaking during planting.
About 300 to 330 cuttings are needed for a row of 100 meters. This translates to a 30 cm planting distance.
Sweet potato needs weeding in its early stages of growth, but once it is established it will come to dominate the weeds.
Sweet potato is excellent as a groundcover to suppress weeds in polyculture or agroforestry farm.
Sweet potato is even relatively shade tolerant and can grow well amongst trees.
The best conditions for sweet potato is a friable soft soil, either sandy or sandy-loam, with plenty of regular rainfall combined with dry season. However even in less than optimal conditions such as in clay soil or droughts sweet potato can still have a good harvest.
Sweet potato is quite resilient and tolerant to different climatic and soil conditions. Even in heavy clay soil sweet potato can still grow well, but the yield would be slightly less.
Inter cropping with sweet potato
Because sweet potato does not climb up and blankets the soil with leaves, good plants to intercrop with sweet potato are plants that are tall and straight such as corn, cassava, pigeon pea, roselle, okra, chili, etc. Pigeon pea is especially well suited, because it is nitrogen fixing.
Squash has a similar growing pattern as sweet potato and the larger leaves of squash might out compete the sweet potato.
However if there are empty patches it could be filled with squash to add diversity.
How to harvest sweet potato
Depending on the variety. Sweet potato can be harvested between 4 and 8 months after planting.
Be careful to not damage the tubers during harvesting as they are fragile and prone to bruising.
It is best to harvest in the early morning when the sun is low to prevent sun damage on the tubers.
Some say that sweet potato should be harvested when the vine turns yellow and withers, however this is only true in temperate climates. In the tropics sweet potato is a perennial and can keep growing for many years and remain green even in middle of dry season.
In the dry season the sweet potato vines might grow very slow and some of the lower leaves can fall off, and the leaves can look droopy, however this is only a water conservation and survival strategy of the vine, it does not mean the vine is death or dying.
In drought or water stress as experienced in dry season the vine will send most of its water and nutrients into the tubers as a water storage to survive drought, which explains why the lower leaves fall off.
This is also the reason why its best to harvest sweet potato in the dry season.