Plant genera in the Protea family (“Proteaceae”) include Banksia (Australia), Grevillea (Australia), Hakea (Australia), Isopogon (Australia), Leucadendron (South Africa), Leucospermum (South Africa), Protea (South Africa)
These plants in the Proteaceae share several requirements and characteristics in common:
1) Either need or prefer good drainage.
2) DO NOT TOLERATE PHOSPHATE FERTILIZER.
3) Prefer deep, infrequent watering.
4) Have showy flowers and/or foliage.
5) Most make excellent cut flowers.
6) Do better in poor soils with minimal care.
Plants in this family typically prefer sandy, rocky, acidic, low-nutrient soils. San Francisco’s sandy soils tend to be well-drained, poor in nutrients, and slightly acid. Our clay soils, however, are different. Most California soils are typically heavy clay or silt, and can be alkaline (especially in the south and inland), higher in phosphorus and poorly drained.
This can create problems if certain requirements are ignored. When planting in the ground, amend the soil with rock for better drainage. Pumice or any kind of agricultural-grade gravel will work. These plants thrive in pots, where drainage and nutrient content can be controlled. We recommend Cactus Mix or Planting Mix.
Refraining from fertilizing is a good bet. These plants have evolved to thrive in very poor soils. If needed, gardeners should use fertilizers with almost no phosphorus and low potassium. Apply at a low strength and infrequently. We offer a low-phosphorus and low-potassium fish emulsion. Cottonseed meal adds nitrogen and acidifies but has a slightly higher concentration of phosphorus. Applying chelated iron in the spring can also be helpful. Fertilizer with phosphorous will poison the plants and kill them.
Tip pruning or light pruning when young is also recommended for proteaceous plants. It helps to prolong the life of most in this group, and it increases plant vigor and better shape. However, don’t cut back more than one-third of the growth, and never cut back to older branches that have dropped their leaves. Most Proteaceae will not sprout from such hard pruning.
These plants are drought-tolerant. All require less than average water. Many will thrive with little supplemental water once established, especially on the coast. Some will tolerate normal (moist) garden conditions and most will not.
Proteaceous plants should not be used in highly watered areas such as near lawns, vegetable beds, or annual color beds.
Third, deep but infrequent watering during the dry season is best. Of course this only applies to established plants. Plants in the ground less than two years and container plants of any age will require closer attention and judicious watering.
Growing plants in this family can be highly rewarding. They are among the showiest and most ornate of all plants when in bloom, and they love our climate. They make excellent cut flowers and have few natural pests or diseases. Try them out and enjoy!