Whenever we think of bulbs, corms and rhizomes we think of tulips and daffodils, flowering in profusion in Holland and gardens around the world. But where do all these underground plants come from?
Tulips actually come from southern Europe to Central Asia, particularly around Greece and Turkey. Many famous flowering underground plants you buy in supermarkets originate from South Africa.
All plants that grow underground are referred to as geophytes, a perennial plant that propagates by means of buds below the soil surface. They are usually perennials which means they have a period of growth and flowering followed by a period of dormancy. Bulbs can be broken down into five different types of storage organs: bulbs, corms, rhizomes, tubers and tuberous roots.
In South Africa we have more than 2 700 species from 15 families that can be classified as bulbous plants. If you travel to a little town in the Northern Cape called Nieuwoudtville, in an area 100km by 75km, you will find more than 1 350 species of plants referred to as geophytes. In KwaZulu-Natal, summer grasslands are filled with many species of geophytes that turn green grasslands into a kaleidoscope of colours. Many require very little attention because they are dormant in winter and flower in summer.
Crinum macowanii (river lily): Found growing in wetlands throughout KwaZulu-Natal and other eastern areas of South Africa. It goes dormant in winter, then in summer pushes out large leaves before producing flowers that are large, bell-shaped, sweet-scented white lilies with dark pink stripes, produced in umbels of 5 to 25 flowers on the tip of a long stalk. Flowers from October to December, and in February in northern Zululand. Ideal plant for a wet area. Easily grown from seed which it produces in large round capsules. Watch out for the Amaryllis lily borer which lays its eggs on the leaves. Once planted do not lift or disturb the roots.
Gladiolus dalenii (Natal lily). This deciduous perennial flowers can be seen along highways and in nature areas throughout Durban during the peak summer months. Growing to 2m high, its flower spike stands way above the grasslands. Dormant in winter, new leaves push through in spring and flower spikes in midsummer (December to February). Each plant produces five tall flower spikes with up to seven large, scarlet orange to red, hooded flowers with a bright yellow throat. Gladiolus dalenii grows in the summer rainfall regions of southern KwaZulu-Natal, from the coast to as far inland as the Lesotho border. It is found in open grassland, woodland and scrub and in rocky areas, often along streams. Cultivars developed in Europe in the early 1900s are grown worldwide and have become very successful cut-flowers.
Crocosmia aurea (falling star). This to me is a winner for all gardens because it grows in sun or deep shade. Its orange sprays of showy flowers stand out in the landscape making it a very colourful perennial in summer. A wonderful garden plant, its cut stems last for a long time in a vase. The plant grows to 1.2m and is found in large colonies in forests or forest margins. Flowers from January to June, mostly a luminous orange, with a few red forms found along the coast in KwaZulu-Natal. It grows best in moist habitats, along stream banks, wooded kloofs and forest margins and combines attractive foliage and showy flowers. Good for mixed borders as they stand proud above most other plants. Easily grown from seed or by dividing large clumps of corms.
Kniphofia praecox (red hot poker). Used in gardens around the world, this perennial is best grown in full sun areas that are quite moist. They will flower throughout the summer before the foliage dies and the plants go into a period of dormancy in winter. They can be very untidy after flowering but do not cut the dying leaves off because the plant is still growing. The sun’s energy through the leaves is important for the plant to survive and for its storage organs for the next season. They grow well along river edges and in perennial borders where the large flower stems push through the leaves and produce a large head of flowers. In large clumps, they give a spectacular show.
Scadoxus multiflorus subsp. Katharinae (fireball lily). Grown in gardens around the world and seen as a collector’s item even though it is very common in cultivation. Each plant only produces one flowerhead a season. The flowerhead, held clear of the foliage, is a large spherical umbel consisting of hundreds of red flowers lasting for up to two weeks under ideal conditions. They grow in semi to deep shade and in wet areas, are adaptable and make a fantastic container plant for summer flowering. If in a container ensure the soil is well drained and the container is in the shade. They will die down in winter before pushing leaves and flower spikes in summer. If you can, plant them in mass because they make a wonderful display in January.
Other summer geophytes for your garden: nerine bowdenii, haemanthus albiflos, agapanthus praecox, gloriosa superba, watsonia, eucomis autumnalis, cyrtanthus sanguineus.
With the recent heat and rains, our gardens will be going crazy with growth and weeds. Keep on top of the pruning and weed removals before they become big problems. With the soil being moist, this is a great time to remove weeds physically.
Continue fertilising for the next three months. With rain, heat and long days around until late March, there is still lots of growth. Wait until it rains before fertilising so it can be evenly distributed throughout the soil and to the root systems.
Remove any dead or diseased leaves and branches. This is where most decay happens and can result in you losing the plants. Use a sharp pair of secateurs to prune.
Continue cutting your lawns at least once a week, leaving growth and just removing tops of the grass. Continue feeding at least once a month with a high nitrogen fertiliser such as 5.1.5. Apply a handful per m2.
Mulch flower beds with leaves that have fallen from the trees or buy well decomposed compost and apply a thin layer over the root base of the shrubs.
Lift groundcovers such as agapanthus, tulbaghia and dietes. Prepare the soil with lots of compost. Split the groundcover and replant. Water well for the first few weeks. The new growth will be much healthier and the plants will thrive with all the rain we have had.
Watch for fungal and insect infestation during the hot humid days when plants are most vulnerable to such an attack. Treat according to the problems you encounter.
Check for invasive aliens in your garden. Next month I will write about the most common alien weeds in your garden and how to eradicate them.
Happy gardening.
The Independent on Saturday