How to grow Pomelo - Citrus grandis from seed?

If you have never come across a ripening pomelo fruit in real life then you are missing out. You just can't help yourself from being impressed by its almost ridiculous size. Like many cultivars within the genus Citrus they are easy to grow from seed but you just need to be aware of two things. As you would expect the seeds of the Pomelo - Citrus grandis (formally Citrus maxima) are seriously large in size and as such tend to have a longer germination period. Secondly, unless you are blessed with living in a warm Mediterranean or subtropical climate you will need to germinate your seeds with the help of a heated propagator. That is not to say that you won't be able to provide decent germinating temperatures in an unheated greenhouse or conservatory over the summer months in the UK or other temperate climates which receive consistent temperatures of around 25 degrees Celsius for six weeks or so. So just how do you grow the Pomelo from seed?

Pomelo seeds
To begin with you can use individual pots, or a seed tray but I prefer to use large modular seed trays. It saves disturbing the root system when it comes to pricking out, and as it it a regular seed tray or half seed tray size it will fit perfectly inside a standard heated propagator. Although not an ericaceous species, I prefer to use a good quality John Innes Ericaceous compost. You can use regular seed composts or multipurpose if you prefer as they will still germinate. Its just that citrus are known to go a little chlorotic and the acid compost seems to reduce this issue.

Place one seed per pot or module and bury one centimetre below the surface. Gently compact the compost before watering in. Place your pots/tray inside a propagator/heated propagator in a bright position with the vents closed to prevent the soil from drying out. Set the heated propagator at between 25-30 degrees Celsius making sure that the compost is kept moist at all time. 

Pomelo seedling

After 2-3 weeks you can expect the first seedlings to emerge, at which point you can open the vents. Once the first true leaves appear then seedlings in pots can be removed from the propagator but still keep them under protection. Do not allow the seedlings to become waterlogged as this can damage the newly developing root system and allow the soil to partially dry out before watering. 

Once established in their pots they can be potted on and hardened off over a couple of weeks before placing outside. They will prefer a warm, bright sheltered position. In the UK Pomelo plants will need to be brought back in under protection once overnight temperatures begin to dip below 12 degrees Celsius. They can either stay in permanently in a cool bright position or placed outside after the risk of late frosts have passed so long as they have been once again hardened of beforehand.

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At what temperatures to Citrus seeds germinate at?

Growing Citrus from seeds is easy, or, at least it should be. However when good natured gardeners try and flex their horticultural wings by planting these babies up for cossetting on their kitchen windowsill often nothing happens and their hopes are dashed! So what is going wrong? Assuming that all other conditions are correct then it is likely to be the soil temperature. So unless your windowsill is in the Mediterranean or some similar warm and lovely environment your seeds just won't have the impetuous to initiate germination. Therefore the question is this, at what temperatures to Citrus seeds germinate at?

The simple answer is at a surprisingly high temperature so assuming you live in a cooler temperate country you will certainly need a heated propagator - unless of course you sow your seeds during the summer months. 

Lemon seeds

A study by R. E. Rouse and J. B. Sherrod at the University of Florida tested the optimum germination temperatures of 17 citrus varieties using a temperature gradient from 15 to 38 degrees Celsius. The results showed that the optimum temperatures for germination Citrus seeds ranged from 25° Celsius for Citrus trifoliata to 33° Celsius for the Citrus limonia and Citrus sinensis hybrid rootstock. This gave a mean optimum temperature for all the citrus varieties covered in this study of 30°Celsius.

This is of course great for a laboratory experiment but for kitchen purposed I would suggest setting your day temperature to approximately 25°Celsius (with the view to increasing temperatures incrementally if germonation hasn't commenced after two to three weeks) and a night temperature of approximately 16 degrees Celsius. With regards to the higher germinating temperatures it is worth considering manufacturing an insulated propagator using a polystyrene box (usually obtained from your local tropical fish shop) and a heat mat.

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How do you grow Actinidia chinensis?

Commonly known as the 'Chinese Gooseberry' or 'Kiwi Fruit', Actinidia chinensis is a vigorous climbing, deciduous species capable of reaching up to 9 metres in height. Native to northern Yangtze river valley in China, it was introduced to Europe in 1900 by the notable English plant collector  Ernest Wilson (1876 – 1930).

It has a dense covering of reddish, hairy shoots and large heart-shaped leaves which can be up to 20 cm wide. The blooms open to a creamy-white colour but fade to a buff-yellow as they mature. The fragrance flowers are produced in clusters over the summer and are approximately 4 cm across. However the most notable feature of Actinidia chinensis are its edible fruits.

Actinidia chinensis fruit
Once the flowers have been pollinated, the fruits appear, first green then turning to brown as they mature. They are 4-5 cm long and resemble a large, elongated gooseberry. Even the flavour is somewhat reminiscent of gooseberry. Actinidia chinensis is dioecious (meaning that the male and female flowers appear on different plants) and so to obtain fruit you will need to plant both sexes in near proximity. Only one male plant is necessary for effective pollination although several females can be planted. So how do you grow Actinidia chinensis?

Actinidia chinensis will be happy growing in any ordinary, reasonably drained garden soil, but will perform best in rich loams. Avoid chalky soils, those lacking in humus (although this can be improved prior to planting) and any ground prone to waterlogging.

Plant Actinidia chinensis from November to March in a sunny or partially shaded position against a high wall, tress or purpose-built supporting structures.Pinch out the growing points when young to encourage a spreading habit.

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How to grow Passiflora edulis 


Commonly known as the 'Purple Granadilla', Passiflora edulis is a tender, evergreen, vigorous climber with highly ornamental blooms and edible fruits. Native to the subtropical and tropical regions of Brazil, Paraguay and northern Argentina, it was introduced to the gardeners of England in 1810.

It is a shallow rooted, self-clinging species, and perhaps most notable for its extremely showy bowl-shaped, fragrant, purple-white passionflowers. The blooms are approximately 6 cm across and are produced throughout the summer. Each flower has white tepals, and a corona comprising of curling white filaments which are marked by a broad, purple band at the base.

Passiflora edulis is also grown for its edible fruit which are round to oval in shape, and either yellow or dull purple at maturity. They have a soft to firm, juicy interior filled with as many as 250 seeds inside. Each seed being surrounded by an orange sac containing juice.

Passiflora edulis fruit
The plant itself can grow to approximately 3-5 metres tall and 1-2 metres wide, clinging to its support by coiled tendrils. The finely-toothed, three-lobed leaves will grow to between  7-20 cm long. They are deep green and glossy above but dull green below with two small glands on the stalks. The young stems are tinged with red or purple.

Passiflora edulis will perform best when grown in moist, fertile, well-drained, sandy loams in full sun. They are in fact tolerant of positions which experience a certain amount of light shade, but this will reduce the number of blooms.

Despite its subtropical and tropical origins it is possible to grow Passiflora edulis in the mildest regions of Northern Europe, however wherever they are likely to experience freezing conditions they are perhaps best grown as a container plant and brought in under protect before the first frost are forecasted. Provide a humus rich compost, plenty of ventilation, and reduce watering.


How to grow Passiflora antioquiensis


Previously known as Tacsonia van-volxem, and originally named by French Botanist Charles Antoine Lemaire, Passiflora antioquiensis was first brought under cultivation in Europe in 1858.

It was subsequently renamed and re-classified under the Passiflora genus by German botanist Gustav Karl Wilhelm Hermann Karsten 1895. Native to the cool highland rainforests of Colombia, the species name 'antioquiensis' was named in honour of the Antioquia Department in Colombia from where the type specimen was collected.

How to grow Passiflora antioquiensis
Commonly known as the Red banana passionfruit or vanilla passionfruit it is a highly ornamental climbing species noted for its rich, rose-red pendulous blooms (one of the largest of all within the passiflora genus) and elongated, banana-like fruit. In European climates the flowers appear during late summer to autumn, each one approximately 10-13 cm across with a small violet corona and an exceptionally long, tube-like androgynophore which can be up to 6 cm long! The blooms are borne singularly on long peduncles which can be up to 70 cm long! Each flower will only last 3 or 4 days and in its native habitat would be pollinated by hummingbirds.

Once pollinated, green fruits will appear which look somewhat like a straight, small banana with rounded ends. After 6 months or so the fruits will fully ripen turning yellow. The fruits are edible with a sweet, slightly tart flavour.

The leave can occur in two distinct forms, either lanceolate, un-lobed leaves or deeply three-lobed leaves which are slender, pointed and downy underneath. Once mature, Passiflora antioquiensis can grow between 5-7 metres in height.

Passiflora antioquiensis will be best grown as a conservatory or greenhouse specimen in climates which are at risk from seasonal frosts. However it is intolerant to excessive heat and will prefers humid, semi-shaded conditions and temperatures of no more than approximately 27°Celsius. Any higher and it will refuse to flower. It has been reported that once mature it will be able to tolerate 2 or 3 degrees of brief frost, although i recommend protecting it from all frost.  Like most passionflowers it will perform best planted in a moist, humus rich, well-draining soil. Water regular during the growing season and feeding with a suitable water soluble fertilizer every 10-14 days.


How do you grow Passiflora incarnata?

Passiflora incarnata is a ornamental climbing plant native to the southern United States. It natural habitats include thickets, riverbanks and unmowed pastures, usually on sandy soils however it will also be found growing alongside roadsides, and railroads. It is a drought tolerant species which will thrive in areas with plenty of available sunlight, although unlike other species within the genus it is not found in shady areas such as beneath forest canopies. So , how do you grow Passiflora incarnata?

It is a fast growing perennial with edible fruits, and is surprisingly one of the hardiest of all passiflora species making it an ideal choice for gardens with a northern European climate. It features glossy, three-lobed, dark green leaves, and under favourable conditions will grow to an approximate height of 2-4 metres with a width of 1-2 metres.

The most noticeable feature of Passiflora incarnata are its highly ornamental, fragrant flowers which are approximately 7 cm wide and come into bloom from July to September. Each flower has five bluish-white petals with a white and purple corona at its centre. Radiating out from the corona is a structure of fine appendages which create a ring between the petals and stamens although these can extend beyond the tips of the petals.

Once pollinated, fleshy egg-shaped, yellowish fruits appear about the size of a hens egg. They appear green at first, but then becomes yellow-orange as it ripens.The edible part of the fruit are the pulpy, jelly-coated seeds within, not the skin.

Grow Passiflora incarnata in most moist, well-drained garden soils in full sun to part shade. They are surprisingly drought tolerant once mature. Apply a loose mulch to the roots in the spring.

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