In the wild, these plants grow in well-drained, nutrient-poor, slight acidic soil.
Plants grown from seed will take 4 or 5 years before they flower. 1
On older plants the side shoots tend to be quite short, so to encourage the development of new shoots and long stems, the stems bearing old flower heads should be cut back to ground level. 1
Older plants also tend to become woody and should be cut back to ground level, where they will sprout again from the thick underground rootstock.1
Because they are used to nutrient-poor soil conditions, only fertilise with organic plant food, such as fish or seaweed emulsion, especially if grown in a pot.
The roots are easily burned by phosphates
Occasionally apply ammonium sulfate sprinkled on the soil and watered well, to keep the soil acidic and provide nitrogen
Don’t disturb the root system once the plant is established – ie, don’t dig or cultivate around the plant
Growing King Protea from seed
Sterilise your seedling soil first by pouring boiling water over it
Because the plants don’t like having their roots disturbed, plant them into a 500ml plastic seedling bag filled with acidic soil mix (about pH 5.5): try 2 parts medium/coarse river sand + 2 parts peat/decomposed pine needles + 1 part vermiculite/perlite
The seeds need to be treated with a “smoke primer” (in the wild, these plants are subject to frequent veld-fires and have adapted to use this for germination).
Dip the seed in a solution of fungicide such as furalaxyl or any ornamental plant fungicide, before planting.
The difference in day and night temperatures should be about 12dC, and the daytime temperature should not exceed 30dC.
Germinate in semi-shade (eg 30% shadecloth) and protect against rodents and insects
Keep the soil moist (but not waterlogged!) with a fine mister – don’t use a coarse mister or you may damage the germinating roots
Don’t allow the seedlings to dry out at all during germination
The seed will germinate three to four weeks after sowing.1
Soil temperature should be kept higher than 4°C / 39°F to ensure good germination.
Transplanting King Protea
Don’t. At least, don’t transplant mature plants. As with other fynbos species, proteas have very delicate root systems and may die if the roots are disturbed. The roots have with dense clusters of short lateral rootlets that form a mat in the soil just below the leaf litter. This is an adaptation to the low-nutrient, phosphorus-deficient soils of its native fynbos habitat.2 Thus, preferably don’t even dig or cultivate around the root system.
Seedlings should be about 1 year old before transplanting into their final location.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as King Protea is a tender plant.
Seed Saving King Protea
Large nut-like seeds have to be treated during storage with a systemic fungicide with the active ingredient of metalaxyl (Apron) and sown from the middle of March (in the Southern Hemisphere), when the day temperature starts to drop. 1
The large flower heads produce a disappointingly small amount of good seeds, only 1 – 30 percent of flowers result in seed. The plant’s need to produce nutrient-rich seeds in a nutrient-poor environment is thought to limit the amount of seeds it can produce. 1
The seeds are quite large nuts, covered by hairs and stay in the old flower head for a year or more. They are released after a fire and dispersed by rodents and birds.1
How long does King Protea take to grow?
These estimates for how long King Protea takes to sprout, grow and harvest are from real observations from real gardeners, right around the world.
Days to Germination How long does it take King Protea to germinate?
25 days
Average 25 days
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Days to Transplant How long until I can plant out King Protea?
+ 365 days
Average 365 days
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Days to Maturity How long until King Protea is ready for harvest / bloom?
+ days
Average days
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Total Growing Days How long does it take to grow King Protea?
Proteas have such a wide diversity of forms (plant size, flower size, growing habit, flower colour), and this is the reason that they were named after the Greek god Proteus, who could change his form at will. 12 The flower bud of the king protea looks so much like the globe artichoke vegetable (Cynara scolymus) that it was given the Latin species name cynaroides1