Proteaceae 101: A step-by-step guide to growing them successfully

by | Jun 8, 2021

Proteaceae A step by step guide to growing them successfully

The mighty Proteaceae! Indigenous to the Cape Floristic Kingdom and exported worldwide for their magnificent long-lasting flowers and bracts. Proteas and plants within the Proteaceae family are not a rare sight here in the Western Cape, where they thrive growing in poor soil and receiving little to no TLC. Yet, you might still find yourself challenged to bring these local gems to their full crowning glory, or may even have had a few fatalities along the way. This is because plants within the Proteaceae family have specific growing conditions that need to be adhered to for successful growing.

Don’t lose hope or give up on growing your own Proteaceae! It is important for us as landscapers and gardeners to conserve this truly unique plant family because of its dwindling numbers due to an increase in invasive alien plants, too-frequent and out-of-season fires, commercial afforestation and the development of housing estates and farms.

But first, let’s look at which plants actually fall within the Proteaceae family (and will be the only ones covered in this blog).

Proteaceae is a family of plants mainly found in the southern hemisphere. It includes:

  • Proteas
  • Leucospermums
  • Leucadendrons
  • Mimetes
  • Orothamnus
  • Serrurias

Learn to grow your Proteaceae step-by-step with Jessica Ruger, horticulturist:

  • What climatic conditions do Proteaceae prefer?
  • What soil do they like to be planted in?
  • How to plant your Proteaceae
  • How to practice mulching
  • How to water your Proteaceae correctly
  • What nutrition do they require?
  • Some basics on pruning

climatic conditions

Climatic conditions vary between all the different types of Proteaceae but there are some requirements that they all have in common. I would always recommend that when choosing your plants, you do your homework first and make sure that it is appropriate for your garden or landscape’s climate. You have very little control over this, and it will be a determining factor as to whether plants survive or not.

  • Full sun is a must-have. All Proteaceae need to be planted in areas where they receive as much sun as possible.
  • Varieties that originate from winter rainfall regions must have good air circulation and cool nights and do not tolerate high humidity in summer, which is why they will not do well in summer rainfall regions.
  • Varieties that grow in mountainous areas are tolerant of very cold conditions and even some snow, so if you are in a cold area, rather choose one of these varieties.
  • Some summer rainfall species are tolerant of moderate frost but winter rainfall species are usually only tolerant of light frost for short periods of time depending on the variety.
  • All Proteaceae plants need good air circulation, so you need to take this into consideration when planting. Try to not overcrowd these plants.
  • Proteas perform best in fairly windy conditions.

Soil

  • Most Proteaceae grow in nutrient-poor sandy soils and they tend to not do well in soils that have a heavy clay component. The general rule of thumb is that the top and subsoil should not contain more than 30% clay. If you have got slightly clay soil then gypsum (neutral, does not alter PH) can be used to slightly alter the structure by separating the clay particles. Do not use lime to do this as it will alter the PH of the soil, increasing it which is not what Proteaceae want at all and is toxic to them.
  • A few Proteaceae which tolerate a more clay soil do exist, but they are far and few.
  • An extremely important factor is that plants from this family require acidic soil with a PH between 5-7 and will not do well in naturally alkaline soils. Hence the reason why they do not do well in clay soils as they tend to be more alkaline.
  • All Proteaceae need a well-drained soil that is well aerated and if they are not in this type of soil tend to rot and develop root fungi which leads to fatalities.
  • If your soil is not perfect then you can also remedy this by digging a larger hole and mixing the soil that comes out of it with composted pine bark or a fynbos potting soil for example Arnerlia potting soil. This gives the plants a transitional layer and means they will not get an immediate shock when roots start establishing.

Planting

  • Winter and summer rainfall areas have different planting seasons. In winter rainfall areas Proteaceae are usually planted in April, May and June – when slightly cooler weather is experienced. In summer rainfall areas planting is traditionally done in August and September – when weather is slightly warmer and frost has passed.
  • When planting, do not use any bonemeal, phosphorus or even normal compost as all are alkaline and compost can contain high amounts of nitrogen, which Proteaceae are also not too fond of. Rather, as previously mentioned, plant with composted pine bark or Arnelia potting soil.
  • Planting distances vary from plant to plant but the general rule of thumb is that varieties that reach a maximum height of 2m should be planted 65cm apart minimum and plants that grow higher than this should be planted about 1m apart. Varieties that grow less than 2m high should be planted about 50cm apart.

Mulching

  • The fact that Proteaceae tend to prefer growing in sandy soils makes it very important to implement good mulching practices. This is because the sandy soils in winter rainfall areas tend to become extremely hot and dry in summer months.
  • Mulching helps to retain soil moisture, means the roots are less exposed and therefore keep cool and also prevents weed development, which is important as Proteaceae roots do not want to be disturbed.
  • If you are experiencing weeds, rather do not tug the weed out, which could disturb the plants roots, but cut it down to below root level to cause minimal disturbance.
  • Another benefit to mulching is that, slowly, as the mulch decomposes, it will release some natural nutrients into the soil that benefits the plant.
  • Typical mulches used for these plants are wood chips, bark nuggets, gravel and crushed rock. You can also mulch using pruned and cut-up material from Proteaceae. Remember that mulches should not touch the base of the plant.

Watering

  • When Proteaceae are young they need a little more water – a good soaking two-three times weekly, but once they become more established they are more drought-tolerant and water-wise. Watering is also dependent on the type of soil they are growing in and if the soil is sandy, more watering than the above is often required.
  • Proteaceae should be watered earlier in the day. If the roots are regularly wet in the evening, this can lead to fungal root infections which can be deadly to your plant.
  • Container-grown plants also require more watering than soil-grown plants, requiring a daily or every second day soaking. These containers should be strategically placed in morning sun and afternoon shade in the summertime to prevent drying out.
  • Remember, correct mulching will also mean that less watering needs to take place.

Nutrition, feeding and deficiencies

  • As mentioned, Proteaceae prefer growing in naturally nutrient-poor soils and therefore do not really need additional feeding.
  • If you feel like your plants do need some feeding, keep in mind that they do not tolerate phosphorus (due to the fact that they will increase the PH) and nitrogen. This rules out, therefore, the use of chemical fertilisers.
  • Normal compost and especially mushroom compost should be avoided as they are high in nitrogen as well as phosphorus.
  • The best fertiliser to use – and what we use at Contours – is Talborne 5:1:5 (16). As this is an organic fertiliser, nutrients are released slowly, as well as phosphorus (the 1 in the ratio) is low which means it will not change the PH of the soil to a higher one which negatively affects Proteaceae.
  • An additional way to provide feeding to your plants is to use pruned material as a mulch by cutting up material and adding it around the base of the plant (not touching the plant). As the organic material decomposes, it will slowly release nutrients to the plant.
  • The most common deficiency experienced by Proteaceae is an iron deficiency. This deficiency crops up if the PH of the soil is higher than 6.5 (alkaline soils). This is quite common in clay soils. The most obvious sign or symptom of an iron deficiency is Chlorosis. This is where the leaves go yellow and the veins stay green. The solution to this problem is to apply either Iron sulphate (5ml per 1L water) or Iron chelate (5ml per 1L water), which is applied over 1m2.

Pruning

  • Pruning of Proteaceae is extremely important to extend the life of these plants and also to maintain a good shape.
  • There are two forms of pruning, namely thinning-out and heading back. Thinning out is the removal of excess, diseased or dead branches at the base of the plant. Heading back is the removal of branches at any point above the base of the plant. This is especially important with branches that have already flowered.
  • Pruning should never be done when plants are wet and sharp secateurs must always be used.
  • The pruning of Proteaceae varies for each type and we would recommend that you visit the Arnelia website for more detailed tips on this particular topic.

In conclusion, if you had some struggles in the past with Proteaceae growing, we hope that these step-by-step tips will help and guide you to more successful fynbos growing in the future. Although not the simplest plants to grow, once you get the gist of Proteaceae growing you will be rewarded with some of the most unique and spectacular flora our world has to offer.

Remember to be on the safe side before purchasing a Proteaceae plant. Research it and make sure it will be the right fit for your garden and climatic conditions. If the rainy days do come, don’t be shy to rush off to your local retailer and find a Proteaceae gem for your garden. This is the perfect season for fynbos-planting in the Western Cape!

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