- How to grow yams
- The place of yams in a crop rotation
- How to prepare the soil for yams
- How to propagate yams
- How to plant yams
- Looking after the plantation
- Harvesting and storing yams
- The Art of Harvesting Yams
- A Guide to Fat Yams
- My best yam planting tips
- Everyday Mysteries
- Question What is the difference between sweet potatoes and yams?
- Sweet Potatoes
- Why the confusion?
- Content: Monocots Vs Dicots
- Key Differences Between Monocots and Dicots
- Sweet Potatoes Versus Yams
- Why The Confusion?
- Breaking news
- How To Grow Oca/ New Zealand Yam (Oxalis tuberosa)
- Thompson & Morgan’s Trial Notes
- Culinary uses of Oca
- Planting Oca Tubers
- Harvesting Oca
- Crop Yields
- How to Grow Yams
- How to Grow Yams in Your Garden
How to grow yams
The place of yams in a crop rotation
It is best to plant yams at the beginning of the rotation, as a first- year crop after clearing the land.
If yams are grown after a long fallow, they find plenty of mineral salts in the soil, and yield many good tubers.
How to prepare the soil for yams
Before planting yams, the soil must be well prepared.
– Clear the land before the rainy season. Cut down the trees, cut the branches. Stack the trees and branches and burn them.
Do not cut all the trees. Leave some of the little ones. They can be used as supports for the aerial stems of the yams. These natural supports will later be supplemented by stakes.
– Till the land to a depth of 20 to 40 centimetres.
– At this time add organic manures, well- rotted farmyard manure, compost or green manure, at 10 to 40 tons a hectare.
Inorganic fertilizers may be used to get a greater yield.
The amounts vary according to the country, region, or even the soils in the same field.
Research stations like IRAT’ make a special study of food crops, and advise farmers.
In Liberia, it is known that the application of potassium (K) fertilizers is valuable in increasing yields.
In Nigeria and Ghana, the agricultural service advises that yams should be given the following fertilizers:
250 kg/ha ammonium sulphate;
65 kg/ha single superphosphate;
215 kg/ha potassium chloride.
The farmer who wants to make progress should all the time ask for advice from the agricultural service.
– In many African countries, yams are planted in mounds 30 to 40 centimetres high and 1 or 2 metres apart. These mounds are made at the beginning of the rainy season. The soil which has thus been well loosened holds plenty of water.
Sometimes the mounds are only made 2 or 3 months after planting. This earthing up encourages the development of tubers but takes a lot of work from the farmer.
If the soil is fairly deep and is deeply tilled, it is not always necessary to make mounds. In that case, more tubers can be planted and the density is greater.
Yams are planted at the beginning of the rainy season. Plant them 5 to 10 centimetres deep 1 metre apart in all directions or 90 centimetres by 1 metre. This gives the tubers plenty of room to fatten up, and the plant makes use of all the rainy season water.
How to propagate yams
Many kinds of yam bear flowers which fruit and produce seeds. So it is possible to obtain new yam plants by sowing these seeds.
But this way of propagating is no use to the farmer. The new plants grown from seed are not always like the parent plants. Often the yield is less, the tubers are much too small and of bad quality and contain a poison called dioscorine.
For all these reasons, it is better to propagate by cuttings. But here care is needed Take cuttings from ripe tubers, and not from the aerial stems, as is done with cassava. These root cuttings make plants which are like the parent plant, and give good yields.
For the cuttings use pieces of tuber or small whole tubers. To get regular sprouting and good yields, the cuttings “whether whole tubers or pieces) should weigh between 250 and 400 grammes.
The amount of yams planted represents a considerable part (about a quarter) of the harvest. That much of the harvest must be set aside and well stored for use in planting later.
Plant only fully ripe tubers. It is best to use the part of the tuber nearest the crown. This top of the tuber contains many growth buds and shoots more quickly than the rest of the tuber. For this reason, tops of tubers must all be planted in the same field.
The remaining yam tubers are planted in another field. They sprout less quickly.
With the Dioscorea bulbifera variety of yams, the bulbils can be planted in the same way as tubers. Wait until they are quite ripe, when they are easily removed from the stem.
Do not plant tubers or bulbils that are damaged, rotten or diseased.
Small yam tuber used for planting
How to plant yams
The bulbils, pieces of tuber or small tubers are planted in the top of the mound at a depth of 5 to 10 centimetres, and covered with soil. When there is too much sun or the light is too strong, cover the mound with grass, so that the sun will not dry out the young plant and the rain will not wash away the soil and the tubers
– In savanna country where there is a long dry period, stakes are not used.
The aerial stems trail on the ground. By covering it, they prevent weeds growing, and protect it against dryness.
A yam mound
Looking after the plantation
CONTROL OF WEEDS
For a good harvest, hoeing must be done two or three times during the early stages of growth.
When this cultivation is being done, the mounds are remade at the same time.
Later, the abundant vegetation of the yams prevents the growth of weeds.
It is then not necessary to hoe.
CONTROL OF DISEASES AND PESTS
Yams have few diseases.
However, rodents, some insects and fungi cause damage.
Damaged tubers rot quickly and cannot be kept for long.
Harvesting and storing yams
Depending on the variety, yams are harvested 6 to 12 months after planting. Lift the tubers when the leaves and stems turn yellow and dry.
Do not leave the ripe tubers too long in the ground, otherwise they become bitter and may rot.
With some varieties, only one crop is harvested. Others are harvested twice.
At the first harvest, after 6 months, the biggest tubers are lifted.
The second harvest is taken 3 to 6 months after the first.
Or the crop may be harvested as and when needed.
Early varieties, such as lokpa, do not store well. These yams should be eaten immediately after lifting.
Late varieties, such as Dioscorea alata, may be stored for 5 or 6 months.
But they must be kept dry and protected from rats and other rodents.
They should be under a roof, on dry ground or on boards supported on posts.
To prevent rot, the tubers should not be heaped up too much.
The Art of Harvesting Yams
How to Tell When Yams Are Mature
One of the first things you need to know before harvesting your yams is whether or not they are actually ready to be harvested! Unlike plants like tomatoes or beans, you cannot gauge for maturity by looking at the produce. After all, yams are tubers, so the edible part of the plant is underground.
However, there are things you can look for to estimate when you can harvest the yams.
- When did you plant the yams? Yams typically take 100 days or more to mature.
- Are the vines still green or have they become yellow? The more yellow and dead-looking the vines, the closer the yams are to maturity.
- Have you had several light touches of frost? Yams are not usually ready to harvest until there have been a couple of nights of freezing temperatures.
Once you have determined that the yams are ready to harvest, you can start to dig them up.
How to Harvest Yams
One of the most common mistakes people make when it comes to harvesting the yam crop is to use a shovel to dig under the plants. This often results in tubers that have been cut by the sharp blade of the tool. There is no sense in growing yams if you have to throw away tubers you have cut with your shovel.
Instead of a shovel, you should use a pitchfork to loosen the soil around the plants, then gently insert the fork into the ground. As you lift the fork, you should see the yams emerging from the soil. Be sure to use the pitchfork all around the base of the plant, as yams tend to form tubers in a circle around the plant. After the soil is loose, use your hands to separate the yams from the earth. Dig through the ground carefully, so you do not miss any stragglers!
Once you have harvested all of the yams, you can store them just like you would store potatoes. If you leave the dirt on them and put them in a cool, dark place, your harvest may easily last all through the winter months.
A Guide to Fat Yams
Yams (oca) are such a fabulous crop – both leaf and tuber are edible, they’re easy care and problem free. There are but two negatives
- They’re in the ground for ages (8 months or so). Use edges, wild areas or containers if there isn’t room in your garden.
- They’re prone to providing a gazillion itty bitty tubers that never leave you (another advantage to planting in wild areas or containers)
Squitty yams are such a disappointment (and no fun for the cook). And though there will always be plenty of smalls (use them for next years seed and to delight the pig), you can create plenty of big ‘uns with these tips.
My best yam planting tips
- Spacings play a big part – make for a generous 60cm
- If you live where Autumns are cool, start your yams early in pots. Fill a third of the pot with potting mix, pop in the yam, then top up with soil. Transplant them into the garden (they transplant happily), in November after risk of frost has passed.
- Don’t go nuts on foliage producing fertiliser. Good compost worked into free-draining soil is all you need.
- Keep them moist through summer – mulch is your friend here.
- Don’t hill them up! New tubers will begin in the hill, diverting energy from the others and the newbies won’t have long enough to develop fully.
- Wait at least a fortnight after the first frost has killed the tops before harvesting.
Question What is the difference between sweet potatoes and yams?
Although yams and sweet potatoes are both angiosperms (flowering plants), they are not related botanically. Yams are a monocot (a plant having one embryonic seed leaf) and from the Dioscoreaceae or Yam family. Sweet Potatoes, often called ‘yams’, are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea or morning glory family.
Sweet potato cultivar Ruddy (left) is sweet and moist and resists insects, unlike the leading U.S. cultivar Beauregard. Agricultural Research Service, U.S. Department of Agriculture
Yams are closely related to lilies and grasses. Native to Africa and Asia, yams vary in size from that of a small potato to a record 130 pounds (as of 1999). There are over 600 varieties of yams and 95% of these crops are grown in Africa. Compared to sweet potatoes, yams are starchier and drier.
Asiedu, photographer, 2007. International Institute of Tropical Agriculture (IITA) Image Gallery on Flickr.
The many varieties of sweet potatoes (Ipomoea batatas) are members of the morning glory family, Convolvulacea. The skin color can range from white to yellow, red, purple or brown. The flesh also ranges in color from white to yellow, orange, or orange-red. Sweet potato varieties are classified as either ‘firm’ or ‘soft’. When cooked, those in the ‘firm’ category remain firm, while ‘soft’ varieties become soft and moist. It is the ‘soft’ varieties that are often labeled as yams in the United States.
Mrs. Adams, wife of farmer near Morganza, Louisiana, preparing sweet potatoes for dinner. Russell Lee, photographer, 1938. Prints & Photographs Division, Library of Congress.
Why the confusion?
In the United States, firm varieties of sweet potatoes were produced before soft varieties. When soft varieties were first grown commercially, there was a need to differentiate between the two. African slaves had already been calling the ‘soft’ sweet potatoes ‘yams’ because they resembled the yams in Africa. Thus, ‘soft’ sweet potatoes were referred to as ‘yams’ to distinguish them from the ‘firm’ varieties.
Large sweet potatoes are ploughed up for migrant workers to pick and sort according to size at Kirby Farms in Mechanicsville, VA. U.S. Department of Agriculture, 2013. USDA Flickr Photostream.
Today the U.S. Department of Agriculture requires labels with the term ‘yam’ to be accompanied by the term ‘sweet potato.’ Unless you specifically search for yams, which are usually found in an international market, you are probably eating sweet potatoes!
International Institute of Tropical Agriculture (IITA) Image Gallery.
The seed in the plant having one cotyledon is called as the monocotyledon, while the seed in the plant having two cotyledons is named as the dicotyledon. Ginger, banana, wheat, maize, palm, onion, garlic are few examples of monocotyledonous plants, while rose, groundnut, potato, tomato, pea, eucalyptus, hibiscus are the examples of dicotyledonous plants.
Knowing the family of a plant is useful in many ways, as it helps us to know many factors about plant and how will it germinate, what kind of seed it is and what are the requirements of it to grow, etc. Among the various family of plants, monocots and dicots belong to the most diversified and occupied family which are Angiosperms.
Angiosperms consist of flowering plants, trees, shrubs, and herbs. There are around 2,50,000 species known of this family. Keeping the ground of the embryo hold by the seed, angiosperms are distinguished in two parts – monocots and dicots. In 1682, John Ray was the first person to give this taxonomic name, later a French Botanist Antonie Laurent de Jussieu popularized this system in 1789.
The cotyledon is the ‘first seed leaf‘, present within the embryo, though it is not the true leaf. If it is a single seed leaf, it is categorised as monocots and if it is the pair of leaves then termed as dicots. But this is not only the point to distinguish them, rather there are other noticeable points too, which are further discussed in this article.
Content: Monocots Vs Dicots
- Comparison Chart
- Key Differences
|Basis for Comparison||Monocots||Dicots|
|Meaning||Plants with the seed having only one cotyledon are called as monocots, and the plant is called as monocotyledons.||Plants with the seed having two cotyledons are called as dicots and plant is called as dicotyledons.|
|Embryo||Contains one cotyledon.||Contains two cotyledons.|
|Flower parts||The flower parts are present in multiples of three.||The flower parts are present in multiples of four or five.|
|Pollen||Pollen tube contain single pore or furrow (monocolpate).||Pollen tube has three or more pore or furrow (tricolpate).|
|Leaves||The venation of the leaf is parallel.||There is the net-like or intersecting type of venation present in the leaf.|
|Leaves are isobilateral.||Leaves are dorsiventral.|
|Monocots have stomata on both upper as well as on lower surface of their leaves and so-called as amphistomatous.||Dicots have stomata only on one surface of their leaves and so-called as epistomatous.|
|Roots||Adventitious or fibrous roots – with many branches.||Radicle or tap roots – with long thick root.|
|Stem||Vascular bundles in stems are scattered throughout.||Vascular bundles in stems are arranged in a ring-like pattern.|
|Secondary growth||Absent, cambium absent.||Present, cambium present.|
|Woody/Herbaceous||Monocots are herbaceous.||Dicots are both woody as well herbaceous.|
|Examples||Sugarcane, banana tree, grass, daffodils, palm, ginger, grains which include wheat, rice, corn, millets.||Mint, lettuce, tomato, legumes which include beans, lentils, pea and peanuts.|
Definition of Monocots
As the name suggests ‘mono‘ means single and ‘cotyledon‘ means the first single leaf produced by the seed of the growing plant. The monocots cover approximately 60,000 species of the total angiosperms. This monophyletic group has created a larger group of plants like onion, garlic, bamboo, sugarcane, wheat, rice, grasses, palm trees, lilies, orchids, bananas, etc.
There are few though essential features due to which they are named as monocots or monocotyledons. Like first and foremost feature is the embryo, which has one single leaf or cotyledon, containing all the essential molecules for the growing plant. Secondly, they differ in the flower petal arrangement which is in multiples of three, like 3’s, 6’s.
The leaf venation is also parallel, the roots are the adventitious type, and they are herbaceous (containing soft stems). They do not have secondary growth, which means they cannot increase their diameter and produce woods.
Definition of Dicots
In contrast to the monocots, the dicots can be defined as the plants containing two or a pair of first leaves (embryonic leaves), produced by the seeds of the growing plants. They cover around 200,000 species of the total angiosperms. Oaktree, daisies, roses, cacti, legumes, carrot, peas, soybeans, cauliflower, cabbage, and such other plants are covered under this group.
The embryo contains a pair of leaves, though they are not real leaves but have all the essential nutrients for the growing plants. They have the flower arrangement in multiples of four or five.
Dicots have the reticulate venation or net-like arrangement in their leaves, this arrangement is responsible for transport of materials like carbohydrates and water in whole plants. Taproot system is present, which has one thick branch buried deep in the soil to gain nutrients and water for the plants.
As these are herbaceous as well as woody, so the stem shows secondary growth and produce woods.
Key Differences Between Monocots and Dicots
Following are the substantial characters to distinguish between the two types of angiosperms:
- Monocots can be defined as the plants with the seed having only one cotyledon, and the plant is called as monocotyledons, while plants with the seed having two cotyledons are called as dicots, and the plant is called as dicotyledons.
- In monocots the embryo has only one cotyledon, the pollen tube contain single pore or furrow (monocolpate), whereas in dicots the embryo has two cotyledons and the pollen tube have three or more pore or furrow (tricolpate).
- The flower parts are present in multiples of three in the monocotyledons, even the secondary growth and cambium is absent, but in dicots, the flower parts are present in multiples of four or five, even secondary growth and cambium is present.
- Another distinguishable feature is their roots which are adventitious or fibrous type in the monocots, while in the dicots they are radicle or tap root type.
- The isobilateral leaves of monocots show parallel venation and the stomata is present on both upper as well as on lower surface (amphistomatous). The leaves of the dicots are dorsiventral and show reticulate or net-like venation, and the stomata are present on one surface of the leaves (epistomatous). The vascular bundles in stems are scattered throughout, in monocots, though it is arranged in a ring-like pattern in dicots.
- Monocots are herbaceous, which means they have a soft, green stem and are not woody, whereas dicots are both woody as well herbaceous.
- Sugarcane, banana tree, grass, daffodils, palm, ginger, grains which include wheat, rice, corn, millets are examples of monocots. Mint, lettuce, rose, tomato, legumes which include beans, lentils, pea and peanuts are examples of dicots.
In the above article, we came to know about the various distinguishable features of the two subparts of the angiosperms, which are monocots and the dicots. These studies will be helpful to know about the plants and their varieties in a much better way.
Sweet potatoes and yams are often labeled interchangeably at grocery stores, but despite popular opinion, these two are not the same thing. They actually come from two different plant families and have many distinct differences. We’ve detailed those differences below, so you never have to be confused again, and can set all your friends straight!
Sweet Potatoes Versus Yams
Yams are a tropical vine from the Dioscorea batatas plant family and are most popular in Latin America and the Caribbean. The majority of the crop comes from Africa where the term “yam” first came from. It was there that African words like “njam,” nyami,” or “djambi” –meaning to eat — were used to refer to the tuber beginning as early as 1676.
Yams have a brown or black skin and off-white, purple or red flesh. They can grow up to 4.9 feet in length and weigh up to 154 pounds. Yams grow best in tropical climates, typically grow for 6-10 months, and are dormant for 2-4 months, with the growth and dormant phases corresponding to the wet and dry season. There are many varieties of yams; 18 different types are cultivated in Jamaica alone!
Yams are a good source of vitamin C, containing 27 percent of the daily value. Vitamin C is beneficial for fighting infections such as colds and flu, as well as aiding in quick wound healing, anti-aging, strong bones, and healthy immune function. Yams also provide good amounts of fiber, potassium, manganese, as well as an abundance of B vitamins.
Sweet potatoes come from the morning-glory (Convolvulaceae) plant family and are believed to be one of the oldest vegetables around, domesticated thousands of centuries ago in Central America. The crop was first introduced to Europe by Christopher Columbus and was then introduced to China in the late 16th century. From there, its popularity spread to other parts of Asia, Africa and Latin America during the 17th and 18th centuries.
You can learn even more about sweet potatoes, their origin, history, and nutritional benefits here.
Yams and sweet potatoes come from two different plant families. Yams are from the Dioscoreaceae family and are a monocot (a plant having one embryonic seed leaf), whereas sweet potatoes are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea family.
Their textures differ as well. Yams have rough and scaly skin as opposed to the smooth skin of the sweet potato. Yams are also drier than sweet potatoes.
Sweet potatoes are much higher in beta-carotene and have that sweet taste we have come to know and love. Yams have a starchy taste and do not contain a lot of beta-carotene. Sweet potatoes offer five grams of protein in an 8-ounce serving, compared to two grams for yams.
Despite their differences, both are delicious in their own ways. In fact, we have used both in our smoothie recipes. Try our Sweet Strawberry Yam Mixer and Sweet Potato Protein to taste the difference for yourself!
Why The Confusion?
Now that you know the differences, you may find yourself wondering why the confusion? One of the main reasons that yams and sweet potatoes are frequently mistaken for one another is the labeling.
The firm varieties of sweet potatoes were produced before the soft varieties in the United States. Once the soft varieties were introduced, the mislabeling began. Since they had been called “yams” in Africa where they originated and closely resembled yams, soft sweet potatoes were labeled “yams” to differentiate from the firm varieties. Today, however, the U.S. Department of Agriculture requires labels with the term “yam” to be followed by the term “sweet potato” — if it’s indeed a sweet potato.
KIRK HARGREAVES Yams are a tasty winter treat
We call them yams in New Zealand, but in other parts of the world these sweet winter tubers are called oca.
If you’ve never grown (or eaten) yams before, buy a bag from your local greengrocer or supermarket and save a few tubers to replant in spring, when all risk of late frosts has passed. Plant in fertile, free-draining soil and mound up.
The most commonly grown variety is red-skinned, but you can get yellow and apricot varieties too.
Sally Tagg Red-skinned varieties are the most common, but you can also get yellow and apricot-coloured yams
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Yams are ready to harvest as soon as their shamrock-like green tops die down, but don’t rush to dig them up too soon.
They don’t start to fatten up until the very end of autumn and, like parsnips and swedes, their flavour will be sweeter if you wait until after the first few frosts.
If you’re not digging them up all at once, it’s worth marking the position of each plant so you know where to dig once they’re dormant.
Yams are a species of oxalis (Oxalis tuberosa), which is worth remembering when you’re harvesting them.
If you don’t get all the tubers – even the tiny ones – out of the ground, they’ll sprout like weeds next spring and you’ll be left with lots of little and useless plants the next season.
To ensure you get all the tubers out, dig deep and dump the soil into a wheelbarrow for easy sifting and sorting. Give them a scrub, but don’t peel yams before cooking.
Unlike spuds, yams don’t need to be stored in the dark. In fact, exposure to sunlight reduces the oxalates in the flesh, which can cause digestive problems like kidney stones, so don’t eat too many raw yams.
Like seed potatoes, they’ll be ready to be returned to the soil when they start shooting out little sprouts from their eyes.
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How To Grow Oca/ New Zealand Yam (Oxalis tuberosa)
Thompson & Morgan’s Trial Notes
As such a novel crop we believe that the New Zealand Yam will become more important to gardeners in the near future – Oca are second only to potatoes in importance in the Andes, and did not suffer blight, or any noticeable pests and diseases in our own trials over the past 2 years. T&Ms Oca was supplied from a large Suffolk garden and so it has acclimatised to British soil and weather conditions over several years. Tubers can come in a host of colours, but our T&M Oca is a predominantly rose or red skinned with a cream or pale orange flesh and some reddish pigment in some of the tubers.
Culinary uses of Oca
Oca tends to have a slightly tangy lemon taste. The flesh is firm but juicy and crisp when eaten raw or lightly cooked, and becoming more starchy if fully cooked. The tubers dont require peeling when eating Oca raw – just wash them clean, and they can be sliced to add a hint of a lemony zest to salads. peeling ocaAlternatively cook them in the same way as potatoes – boiled, baked, grilled or fried. They also make an excellent addition to winter soups and stews. Our T&M; Oca loses its skin colour on boiling and turns a more cream colour and loses any lemon flavour, becoming more nutty in taste. The tubers contain over 70% water but are nutritionally rich with carbohydrate, calcium and iron. You can even pick some of the fresh leaves in summer for their tangy, lemon taste which adds that bit of zest to a green salad.
Oca tubers contain oxalates (as a member of the oxalis family) as is evident when the plants are growing, with their distinctive oxalis leaf shape. Although gardeners need not worry as these Ocas are not invasive. Oxalates, concentrated in the skin of the tuber, are reduced if the harvested tubers are exposed to sunlight (tubers do not go green like potatoes). This process also sweetens the taste.
Planting Oca Tubers
The small tubers are best planted individually in a 15cm (6″) pots of multipurpose compost during April. As they are frost tender they should be grown on in the greenhouse or on the windowsill. Plant out the small plants when frost risk has past in late May and cover the plants with fleece until established. Each tuber makes quite a bushy plant so allow at least 90cm (36″) between plants for optimum tuber production. Some of the stems which rest on the soil will readily root and the plant can grow to a sizeable bush. Oca also make a decorative container plant throughout the summer and up to the first frosts when the foliage will die back.
Alternatively, tubers can be planted directly outdoors in late May. By this time they may well be showing small sprouts. Plant Oca directly into a shallow drill, about 8cm (3″) deep, and cover with soil or compost and a layer of fleece. Remove the fleece from early June or as the soil and weather warms. Plants can be earthed up as you would potatoes to give some further growing room and anchorage, although this is not essential. Oca prefers well drained soil and an application of a general fertiliser will be appreciated as the plants grow. A mulch of well rotted compost or grass cuttings around the plant during summer will keep the soil moist and aid the plants growth. Water plants well during dry spells, and especially from mid September when tuber initiation commences, as this will promote larger tubers.
Watch the video below to find out more about how to grow Oca (New Zealand Yam):
to watch part 2 of Thompson and Morgan’s ‘How to grow Oca’ videos.
to watch part 3 of Thompson and Morgan’s ‘How to grow Oca’ videos.
The essential point to remember is that the tubers form and swell as autumn develops, when day length shortens and temperatures fall. Ocas do not form underground tubers until very late in the season. Do not worry at all if the foliage gets frosted – it will die off after a heavy frost. Some plants may form some small aerial tubers on the stem. These need to be picked off before a heavy frost. Do not harvest the underground tubers until the last remnants of foliage has become frosted and died off from late November and into December. The longer you can leave the tubers in the soil the better. Lift the tubers carefully, dry them and taking care not to bruise or damage them, then store in slatted trays or a hessian sack in a cool shed or garage. Tubers do not need covering against the light, and will store happily for several months until sprouting commences and some of these can be replanted.
In our trials a wider spacing gave a higher percentage of larger cylindrical, slightly tapering tubers averaging 10cms (4″) in length and 35g (1.25 oz) weight. We harvested an average of 50 tubers per plant of varying sizes. In a really good growing season, and allowing plenty of autumn and winter days to fully develop the tubers, then 0.75 kg (1.6 lbs) per plant may be possible.
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YAM GROWING INFORMATION © Frances and Jeff Michaels
BOTANICAL NAME: Dioscorea alata
COMMON NAMES: Greater Yam; Chinese Yam; White Yam
ORIGIN: Tropical Africa
Yams are a very ancient food plant, believed to have been cultivated for more than 12,000 years. They are twining vines with shiny, heart-shaped, purple-tinged leaves and grow from underground tubers which have a brown skin and white flesh and can weigh many kilos. Yams require a fertile, well-drained soil with a high organic matter content. Plant at the beginning of summer in areas that receive a wet season. They will grow in full sun or semi-shade but need a trellis. Plants need plenty of water during the growing season.
Always peel before using as food. Yams can be used in the same way as potatoes, but are probably best baked, the flavour is fairly bland. In Japan, yam is dipped in batter and fried for tempura. In Malaysia, yams are used in a coconut milk dessert.
Recommended planting time: Plant at the beginning of the warm weather, tubers that have been stored will usually begin to sprout as the weather warms up.
Planting depth: Plant the tuber a few cm below the soil surface.
Plant spacing: Space plants 50 cm apart.
Tubers are ready to harvest when the vines die back in late autumn. Excavate carefully to avoid damaging the skin, start a fair way back from the leaf stem. Tubers can be stored for many months in a cool, dry place.
Reference: ‘The Yam: A Tropical Root Crop’ by L. Degras
How to Grow Yams
Today we’re going to show you how to grow yams with our easy to follow gardening guide. Contrary to popular belief though, yams are NOT sweet potatoes as they are from completely different plant families. Yams are native to Africa and Asia while sweet potatoes are native to tropical Center and South America and the Caribbean. Additionally, yams contain more sugar than sweet potatoes, and can grow to giant sizes of 7 feet long and 150lbs. Real yams also need up to a year of frost free climate before harvest, whereas sweet potatoes are ready for harvest within 100-150 days. There are also 600 different species of yams with just as many uses! So now that you know what the difference between yams and sweet potatoes is, let’s dive in and check out how to grow yams!
How to Grow Yams in Your Garden
Growing any variety of yam requires a tropical to subtropical environment. So if you don’t live in either of these environments or don’t have a greenhouse, growing yams may not be a good idea.
- Choose small whole tubers or portions of larger tubers to plant.
- Plant in good quality, well draining soil.
- These should be planted in temperate zones in March-April.
- Full harvest should be ready within 10-11 months.
- Make 42 inch rows and space each plant 18 inches apart and 2-3 inches deep.
- You can also plant them on hills, making sure to space them 3 feet apart.
- For best results, plant near a fence or build a trellis.
Caring for Yams:
- Plant only in tropical or subtropical regions.
- Full sun.
- Water regularly.
- Harvest in 10-11 months.
As you can tell, aside from being in the right environment, yams aren’t very hard to grow as they don’t require much care, only patience!
There is nothing better than growing something new and having it work. In early spring I wanted to try growing yams and sweet potatoes but it was very difficult to find the slips used for growing. I knew then I would have to try rooting some myself.
I bought a selection of yams and sweet potatoes from various sources, some organically grown and some not. I was able to find some super sweet California yams, regular yams and sweet potatoes. I grabbed my mason jars and filled them with water so that each half of a potato would be touching the water. I used toothpicks to support the potatoes along the side of the jar. What was interesting is one end of the potato roots better than the other which makes sense. At some point they were grown with one end as a root end and the other attached to the plant. They grow just like regular potatoes forming tubers as they grow. Conditions need to be warm out before they can go outside. The yams and sweet potatoes rooted quickly sending their roots deep into the water. Once they were rooted I potted them up in a pot of soil in the greenhouse until they could go outside.
Here yams and sweet potatoes are planted outside in June when the soil is warm. I actually broke slips off the potatoes as they grew and planted them in separate pots. The original plant continues to make slips all season long. They root within a week. The rooted plants were transplanted outside to a raised bed in early June. I chose an area on the south side of the greenhouse guaranteed to get reflected heat from the greenhouse windows. It worked! The photo above was taken at the end of June. Did you know sweet potatoes are a member of the morning glory family? I planted the rooted cuttings about 12″ apart. They need a loose soil so they do well in raised beds where you can amend the soil easily.
This week I couldn’t wait any longer. I had to see how the plants were doing. I gently dug around the outside of the plants and was surprised to see how far they grew underground. They came up as a large clump and all kind of curled together.I am not sure if that is normal as its my first time growing them. The photo at the top of the page is what I harvested from two plants. They are not huge like grocery store yams but still okay to eat. You can see how tiny new yams are hanging down below the clump so if we had a longer growing season I would have left them in the ground to mature.
As the plants grew, they set roots into the soil as they spread along the soil surface. You can see above how roots formed to create new plants. So will I grow them in 2017? Yes, but I think I will try to plant them a couple of weeks earlier and maybe warm up the raised bed with a layer of black plastic for a couple of weeks. When harvesting you need to remove as much soil as you can from the tubers so they store well. I brought these yams into the kitchen to dry and they have done well sitting in a bowl on the counter. I have since found out that sweet potato and yam slips are not sold here as this crop does not store well. The rest of my crop is still in the ground and will be harvested in the next two weeks.
Update: After a reader comment earlier I thought it would be fun to see if you really know your yams and sweet potatoes. Most grocery stores don’t sell real yams but they are named yams just to confuse us. I am not sure why that is. Anyway, here is a that somewhat explains the differences.