Ladyfinger cactus

Ladyfinger cactus: how do you recognise it?

Habit

Clump-forming cactus, about 15 cm tall and up to about 30 cm across, with many slender, cylindrical stems.

Stem

About 1.5–3 cm thick, covered in small tubercles (nipples), fresh green with a dense coat of spines.

Spines

Many short, fine spines per tubercle, golden yellow to brown; they are not hooked but can still prick.

Flower

Small cream-white to pale yellow flowers about 1–1.5 cm across, in a ring around the top, in March–April.

Roots

Fine, shallow roots: a wide, not too deep pot suits it best.

Flowering: March–April · Plants: March–April

Why grow it?

• Compact and neat: an attractive cushion of stems that needs little room on a windowsill.
• Flowers in March–April with a ring of small cream-white blooms, often year after year.
• Very little work: little water, no pruning and hardly any feeding.
• Easy to propagate: detached stems root readily and quickly fill a pot.
• The golden spines brighten up a row of pots of cacti and succulents.

Ladyfinger cactus: where does it grow best?

• Full sun, for example on a south- or west-facing windowsill. In summer it may go outdoors, under cover and sheltered from rain.
• Very free-draining, mineral mix: cactus compost half and half with coarse sand, fine grit or pumice. Neutral, not a peat-rich soil.
• Dry: let it dry out completely between waterings and never let water stand in the saucer.
• Enough room and fresh air, also in summer; a clump 30 cm across needs a pot 12–15 cm in diameter.

Light

Sunny

Potting soil

Cactus compost

Acidity

Neutral

Watering

Sparingly

Size

0.15 m tall, 0.3 m wide

Temperature

Minimum 5 °C

Goes well with

• Echinopsis: A round cactus with large flowers that contrasts with the small blooms.
• Echeveria: A blue-grey rosette next to the golden spines.
• Haworthia: Also stays small and is happy in the same mineral mix.
• Stonecrop: A low, fleshy plant to fill gaps in a dish.

Ladyfinger cactus: when and how to plant it?

Plant in March–April.

1. Repot in March–April, at the start of growth, or as soon as the plant fills its pot. Every 2–3 years is enough.
2. Wear thick gloves or fold a piece of newspaper around the plant to hold it; the spines prick.
3. Choose a wide, not too deep pot with a drainage hole; terracotta dries out faster than plastic.
4. Fill it with a mix of cactus compost and coarse sand or grit, set the plant at the same depth as before and firm lightly.
5. Do not water for about a week after repotting so that damaged roots can heal.

Care

Water

From April to September water when the soil is completely dry, roughly every 1–2 weeks depending on the heat; let the excess drain away. From October to March almost no water or none at all.

Feeding

From May to August, once a month, give a weak dose of cactus feed (half of the recommended strength). Not in winter.

Light

Plenty of sun. After winter, get it used to strong sunlight gradually, or it will get yellow or brown sunburnt patches.

Air

Keep the spot well ventilated and dry; in summer it enjoys fresh air.

Repotting

Every 2–3 years in spring, in fresh, mineral mix; stems hanging over the rim can be used as cuttings.

Tip: A cool, dry winter at 5–10 °C is the secret of flowering: give no water from October to March and keep it as bright as possible.

Ladyfinger cactus: when to prune it?

When: A Mammillaria is not pruned. You only remove dead or rotten stems and, in spring, possibly a few stems for propagation.

How:

• To take a stem off, twist it loose or cut it close to the base with a clean knife. Wear gloves or use folded newspaper.
• Cut away rotten or shrivelled stems back to healthy tissue and let the wound dry for a few days.
• Remove flower remains and debris between the stems with tweezers.
• Use the cut stems as cuttings; see propagation.

Pruning calendar and basic rules

Propagation

Cuttings (side stems)

In spring or summer twist or cut off a stem. Let it dry for 3–7 days and set it in a dry, sandy mix. Give a small drop of water only after 2–3 weeks, once it has rooted.

Seed

In spring sow on a sandy mix, barely covering the seed, under clear film at 20–25 °C in a bright place. The seedlings grow slowly and take a few years to become adult plants.

Ladyfinger cactus: how does it get through the winter?

• Not hardy in Belgium: keep it above 5 °C. In winter keep it cool, at 5–10 °C, and as bright as possible.
• Keep the mix almost or completely dry from October to March; a cool, dry winter is needed to make it flower in March–April.
• Do not leave it in a cold, damp draught by a window: cold plus wet causes rot.

Diseases and pests

• Rot: Soft, brown or dark base of the stems, usually from too much water or watering in the cold. Stop watering, cut the rot away back to healthy tissue and root a healthy piece as a cutting.
• Stretching: Thin, pale, elongated tops mean too little light. Move it to a sunnier spot; the stretched part unfortunately stays that way.
• Mealybug and scale: White, cottony tufts or brown scales between the tubercles. Remove them with a soft brush or cotton bud; left alone they spread quickly, so isolate the plant from others.
• Sunburn: Yellow or brown patches after sudden strong sun, for example after winter. Get it used to the sun gradually; the patches do not go away, but new growth is healthy.
• No flowers: Usually too little light or a winter that is too warm and too damp. Move it closer to the light and give it a cool, dry winter.

Through the year

• January: Rest: dry and cool (5–10 °C), as bright as possible. No water.
• February: Rest: dry and cool. No water.
• March: Flowering begins. No water, plenty of light. Repotting possible.
• April: Flowering. Start watering when the soil is dry. Repot and take cuttings.
• May: Water when the soil is dry. Start feeding.
• June: Water when the soil is dry and feed. Plenty of sun and fresh air.
• July: Water when the soil is dry and feed.
• August: Water when the soil is dry. Last feed.
• September: Last watering when the soil is dry. No more feeding.
• October: No more water. Keep cool and bright (5–10 °C).
• November: Rest: dry and cool.
• December: Rest: dry and cool.

Did you know?

• The name Mammillaria comes from the Latin mammilla, ‘little nipple’, and refers to the tubercles that carry the spines.
• On a Mammillaria the flowers do not come from the spine cushions themselves but from the axils between the tubercles, often in a ring around the top.
• The genus Mammillaria has around 200 species and is one of the largest in the cactus family.