Polyembryonic Seeds

2015/12/22 deej 0

Plants grow from seeds, but what many people do not know is that not all seeds contain just one plant embryo. Many varieties of mangos, for example, have polyembryonic seeds, as do most citrus.

A polyembryonic seed is one which contains multiple embryos. Poly-embryonic seeds produce a number of shoots, one of which originates from fertilisation. The fertilised seedling is often weak and stunted and should be discarded. The other seedlings are clones of the mother tree. Yes, clones – just like a cutting, only from seed.

This means that if you grow a polyembryonic mango (such as Kensington Pride or Bowen, which is pretty much the only variety that we can buy in supermarkets in WA) or citrus (Valencia orange, Lisbon lemon, West Indian lime, Thompson or Marsh grapefruit, Murcott, Kara mandarin, amongst others) variety from seed, it will be true to type. If only the same were true of stone fruit and grapes – although even there, there aren’t really many genes left that aren’t for amazing delicious fruiting capacity, so it’s worth trying to grow those from seed too. You might get a gorgeous new variety, or something very close to the parent.

Back to mangoes.

I have one mango tree, about two years old now and planted out in the ground, which I grew from seed. Mostly by accident to be honest – I put the mango pip in the worm farm, and a month or so later when I emptied that level to put some worm castings into a garden bed, the seed still hadn’t started to decompose. It had, in fact, sprouted. So I planted it in a pot with some worm castings and potting soil, and watered it every day, and it turned into a tree.

Mangoes are really very easy to grow. The recommended process is to keep the seed after eating a mango, and remove as much flesh as you can, then let it air dry for a day or two (in dry weather, such as we often have in Perth, probably err on the side of less drying time, or dry it in a humid environment like a worm farm). You can plant the whole seed in a warm, moist place and wait for it to sprout – at which point you remove all but one of the seedlings, or gently separate them and grow them all on individually. Alternatively you can separate the embryos out to plant individually; to do this, you have to very carefully open the mango seed. Cut a small corner off the seed, and then break it open. You should see several small, bean shaped seeds, which should be white (ratehr than grey and shriveled, which would mean that they’re not viable). Plant each of these bean-shaped seeds in a warm, mopist place; they should sprout in about ten days. The same technique works with citrus seeds, but they’re smaller so you have to be more careful if you want to separate the embryos out to plant individually.

The Ag Department says that there are three varieties of mango available in WA: the Kensington Pride (polyembryonic), R2E2, and Edward. Other varieties suitable for the Perth area include Haden, Namdok Mai, and Kent. Seedling trees should produce their first fruit at 3 – 4 years old, but will not produce a good crop until they are around 7 years old. Young trees can be killed by frost or cold weather, so don’t plant them out until they’re at least a metre tall.



hot chocolate: Theobroma cacao

2015/06/23 deej 0

The middle of winter is stormy, wet and grey. More so than it has been for the last few years, which is making me regret the fact that my water tanks aren’t in place yet to catch some of the rain – but at least the swales are catching it. The whole property is green, and the soil is starting to look like something living in a lot of places, dark and crumbly and full of mycelium. We have clover sprouting and fungi springing up all over the place, and a few of the lupins from last year must have self-seeded because there are lupins growing.

Living here, the seasons are a bit backwards from what you expect. Summer is the dead time, hot and dry, and winter is green. Cold, sometimes, but wet and lush and fertile. I imagine winter as a cold-fingered fertility goddess, full of the promise of life.

cacao fruitUnfortunately, that doesn’t help me get out of bed in the morning when it’s still dark and cold. So today’s post is about something that does help with the dark and the cold: chocolate. Or, more accurately, Theobroma cacao.

Cacao trees are the source of chocolate, and have been cultivated for that purpose for more than 2000 years. Thery are native to Central and South America, and there are archaeological records showing that the Olmecs living in Mexico and Guatemala established their first cacao plantations around 400 BCE. By 250 CE the Mayans depicted cocoa in their elaborate hieroglyphic writings and on carvings and paintings.

Cacao is a smallish, evergreen rainforest tree, naturally growing as an understorey plant in tropical forests. It grows to be 4 – 8 m tall, rarely up to 20 m, and requires the shelter of taller canopy trees to protect it from direct sunlight. In cultivation, cacao trees are often grown under banana plants, coconut palms, or other large, tropical trees. Cacao grows best in regions of high humidity and stable temperatures, areas found only in the tropical zones within 20 degrees north or south of the Equator. It is a pretty tree, with smooth, brownish bark and glossy, bright green leaves, 20 – 30 cm long and 7 – 8 cm wide. The trees live for up to 100 years, but cultivated trees are considered economically productive for only about 60 years.

cacao flowersCocoa trees begin to bear fruit when they are three to four years old. They are cauliflorous, producing their clusters of small flowers directly on the trunk and older branches of the tree. Flowers are yellowish white or pink with red style, filament, and calyx, and are produced throughout the year. In the wild, cocoa trees are pollinated by midges, and only about 5% of flowers receive enough pollen to start fruit development. The fruit is a yellowish, red or brown colour when ripe, 15 – 20 cm long, and egg shaped, with white pulp around the seeds. The pulp is edible, and can be fermented to make an alcoholic beverage. The cocoa tree bears two harvests of cocoa pods per year. Each pod (fruit) contains 30 – 40 seeds.

When the seeds are ripe, they rattle in the capsule when shaken. If the seeds are separated from the capsule, they quickly become infertile, but if kept in the capsule they retain their fertility for a long time. When ripe, the fruit are cut open and the seeds surrounded by their sweetish acid pulp are allowed to ferment so that they can be separated from the shell more easily. The fermentation is also essential in the development of the chocolate flavour. The seeds are then usually dried in the sun, or sometimes in a steam drying shed.

cacao illustrationEach seed contains a significant amount of fat (40–60%) as cocoa butter. Their most noted active constituent is theobromine, a compound similar to caffeine, which makes up about 1-3% of the seed. Chocolate and cocoa are prepared by grinding the beans into a paste between hot rollers and mixing it with sugar and sometimes other ingredients (such as starch or milk powder). Cocoa butter is the fat which is removed from the cacao paste during manufacture; it is a cream coloured solid which smells like chocolate but tastes bland.

Cacao trees will produce 300 – 900 kg of dry cocoa beans per Ha, and given that the recommended planting density is 800 – 3000 trees per Ha, each tree might produce anywhere from 100 g to 1.25 kg of cocoa beans per year – call it an average of 500g of beans per year. The beans are roasted, then cracked and the shell and germ removed, leaving the nibs. Nibs make up about 87% of the bean, so each kg of beans produce about 870g of nibs. The nibs are then ground into paste called cocoa liquor, which is about 50% cocoa butter. So each kg of cacao beans can produce 430g of cocoa powder and 430 g of cocoa butter. Alternatively, you can produce chocolate – using 300 – 700 g of cocoa liquor and up to 20% as much cocoa butter as there is cocoa liquor per kg of chocolate produced (the rest is sugar, milk powder, and vanilla). So for each kg of cacao beans, you could produce about 500g of 50% dark chocolate, and 185 g of cocoa powder. Using our average of 500g of beans produced per tree each year, with one tree you could produce one large block of chocolate per year (250g) and 2/3 cup of cocoa powder (90g).

What cacao needs:

  • Water – The distribution of annual rainfall for regions in which cocoa is grown is 1250-3000 mm per year. The rainfall must be well distributed and any dry period should be no longer than three months.


  • Humidity – Cacao is typically grown in regions where daytime humidity reaches up to 100% and night time humidity is between 70 and 80%.


  • Sunlight / Shelter – Cacao needs shelter both from direct sunlight and from wind damage.


  • Soil – Free-draining, fertile soils with a depth of at least 1.5 m are preferred. The pH range is from 4.5 to 7.0, preferably close to 6.5.


  • Space – Density may range from 800-3000 trees/ha with about 1200 trees/ha being common in Malaysia. That means that each tree needs 3 – 12 sqm of space.


  • Warmth – Cacao requires warm, stable temperatures, and is killed by frost. The ideal range of temperatures for cocoa is minimums of 18-21°C and maximums of 30-32°C.

cacao tree
What cacao has to offer:

  • Chocolate! (Edible seeds, fruit pulp, and oil from the seeds). Each tree should produce enough seeds to make 250g of chocolate and 90g of cocoa powder per year.


  • Attractive, ornamental tree for landscaping if your garden is located somewhere within its climatic tolerance.


  • New trees from seed or cuttings, marcotting (air-layering), or budding.

cocoa beans


Images sourced from Wikimedia Commons:

Plant Profiles: Pineapple

2012/05/08 deej 0

When people think of good permaculture plants – or even good garden plants – for Perth’s Mediterranean climate, pineapples don’t generally leap to mind. At a guess, I would say that most people have never considered that they could grow pineapples. It’s a shame, because pineapples actually love the heat and the sun here, and will grow in marginal areas and thrive on very little water. Pineapples will also grow quite happily in pots, so they can be moved if necessary.

The pineapple plant, Ananas comosus, is a tropical herbaceous perennial. It grows up to 1.5m tall, and the same across, although usually it won’t get taller or broader than 1m. The plant has a short, sturdy stem and narrow, waxy leaves 30 – 100cm long, often with sharp spines along the edges.

In the first year of a pineapple plant’s life, the stem lengthens and thickens, bearing numerous leaves in close spirals. After about 12 to 20 months, the stem grows into a spike-like inflorescence up to 15 cm long, holding over 100 spirally arranged flowers. Flower colours vary, depending on variety, from lavender through light purple to red. The ovaries develop into berries which coalesce into a large, compact, multiple accessory fruit.

A pineapple plant flowers only once, when it is 18 – 24 months (i.e. 1.5 – 2 years) old, and produces one fruit before it dies. The fruit takes about 6 months to develop after flowering. Pollination, generally by bats or hummingbirds, is required for seed formation – but the presence of seeds negatively affects the quality of the fruit. Seeds, if present, are in the fleshy part of the fruit just below the rind. Vegetative reproduction is more common, via slips, suckers, and pineapple tops.

Suckers, also sometimes called ‘pups’, are little side shoots that are produced in the leaf axils (between the leaves) of the main stem. Some varieties will produce more suckers than others, some will start earlier and others later. But they all produce at least a few suckers before they die. If you leave the suckers in place you get what is called a “ratoon crop”. That is the least amount of work for the next crop, just do nothing, but it has a few disadvantages. The plants start getting crowded, and compete for food, light and water. The result of this is that the next crop of fruit is much smaller. The other disadvantage is that if you leave the suckers in place you only get a few suckers and the original pineapple plant, having successfully reproduced, dies. If you keep taking the suckers off, the plant will survive longer and continue growing more suckers. The timing is not critical. Even tiny baby plants can survive, although it is best to wait though until they are a reasonable size, say about 20 cm long. Plants grown from suckers will flower in about 18 months.

Slips are the tiny plantlets that grow at the base of the fruit on the fruit stalk. Not all pineapple varieties produce slips. Slips can be carefully snapped or pulled off. Do it as soon as they are big enough to handle (say about 10 to 15 cm) because slips develop at the expense of the fruit. The parent plant will not produce more slips if you take them off as it would with suckers. Plants grown from slips can fruit within a year.

The easiest way to grow a pineapple is from a pineapple top. Cut the spiky top off of a pineapple fruit, and make sure you remove all the flesh, and even some of the small lower leaves from the pineapple top. Some people recommend allowing the pineapple top to dry for 3 or 4 days, but it isn’t really necessary. Just make a small hole in the ground or in some good quality soil or potting mix in a pot and stick the base of your pineapple top in that. Push the soil back in and firm it around the base so the pineapple sits straight and doesn’t fall over. If the soil is dry give it some water. It’ll grow. It’s that easy. Water the young plant regularly for the initial six to eight week establishment period, and provide a very dilute organic foliar fertiliser spray. After that, the pineapple plant will thrive even with very little water and attention. Plants grown from pineapple tops will take 20 – 24 months to flower, and then another six months or so before the fruit is ripe.

The fruit is ready to pick when it starts to turn yellow. You can pick the fruit at this point, especially if it is getting sunburned or is in danger from animals, and leave it in a cool, dry place (e.g. on the kitchen bench) for a few days. Otherwise leave the fruit on the plant until it’s fully ripe and yellow.

What pineapples need:

    • Water – about 700 to 1000mm rain or irrigation annually, although they can survive and fruit with much less. They have very tough leaves so they don’t lose much water through evaporation.


    • Sunlight – In cooler climates, pineapples need a lot of sun. In very hot climates they like growing under a bit of shade. In Perth they will thrive in full sun or part shade, but they do appreciate being protected from the hot Westerly afternoon sun.


    • Soil Pineapples don’t need much soil or high quality soil, although they do prefer it to be slightly acidic. They do not have a big root system, and get a lot of their nutrients through their leaves. Pineapples do need good drainage – the surest way to kill a pineapple plant you are trying to grow is overwatering and rot. Pineapples also appreciate thick mulch, and a good compost. Mix compost in with your soil before you plant the pineapple, and then mulch thickly around it. You end up with mulch and compost sitting in the bottom leaves, and as it breaks down it feeds the plant.


    • Food (Fertiliser) – Pineapples take up a lot of their nutrition through their leaves, and the first few months after planting they rely only on their leaves. You should make sure the plant food actually lands on the leaves. Artificial and concentrated fertilisers will burn the leaves, so it’s best to stay away from them. You can use liquid fertilisers like fish emulsion, seaweed extract, or worm tea. Make a very diluted solution and apply it to the pineapple plant’s leaves and the surrounding soil with a watering can or spray bottle. The colour of the leaves of your pineapple plant will tell you how healthy it is. If they have a reddish, purple tinge then your pineapple is starving and you should help it a bit with some liquid fertiliser.


  • Space – Pineapple plants can grow up to 1.5m tall and 1.5m across. Make sure you put them in a place where they can spread without becoming a nuisance. They work well planted in clumps.


What pineapples have to offer:

    • Pineapples produce beautiful flowers, and their unusual look can make a very attractive focal point in a garden.


    • Fruit from your own homegrown pineapples will taste better than anything you can buy at a supermarket, and it will be free of pesticides, herbicides, and other nasty chemicals.


    • Pineapple plants also produce more pineapple plants, with very little effort on your part.


    • Their spiky leaves make them an effective barrier to keep animals or people out of garden beds, or away from other areas, which need protection. A pineapple fence will keep out possums, wallabies, children, dogs, …


  • The spiky leaves and shallow, fibrous roots of a dense planting of pineapple plants makes an effective mulch-trap, preventing soil and mulch form being washed away by rain or irrigation, and slowing down the movement of water down a slope. The lee side of this sort of soil dam will build up rich loads of humus, which benefits the pineapples and any other plants in the area.


What pineapples do not like:

    • Soggy, waterlogged soils


    • Having their leaves burned with concentrated fertilisers


  • Frost


More Information?

  • http://www.tropicalpermaculture.com/growing-pineapples.html
  • http://www.tropicalpermaculture.com/pineapples-permaculture.html
  • http://www.hort.purdue.edu/newcrop/morton/pineapple.html
  • http://www.ipmcenters.org/cropprofiles/docs/hipineapples.html


Images sourced from Wikimedia Commons: