Asparagus fern

Asparagus fern (Asparagus setaceus) is an easy, fast-growing houseplant with soft, feathery sprays of green. It is not a true fern. It belongs to the asparagus family. Give it bright, indirect light and keep it out of direct sun. Water it when the top of the soil dries out, then let the extra water drain away. It likes humid air and temperatures from 55°F to 70°F (13°C to 21°C). Plant it in a moist, well-drained, peaty potting mix. The berries are poisonous, so keep the plant away from children and pets.

Pick this plant if you have a bright room with no harsh afternoon sun and you want quick, lacy growth for a shelf or a hanging basket. Skip it if you have a cat or dog that chews plants, or a toddler who might grab the berries. The stems also carry small spines, so wear gloves when you repot or trim it. Most of the care notes below come from the North Carolina Extension Gardener Plant Toolbox.

Asparagus fern basics

Asparagus fern grows wild from central Ethiopia down to South Africa. NC State Extension calls it “one of the fastest-growing, least demanding houseplants.” In the wild it can scramble up to 10 to 20 feet. In a pot it stays around 2 to 3 feet tall and wide.

The green “needles” are not true leaves. They are tiny flattened branches called cladodes. The true leaves are small dry scales on the stems. The stems are wiry, they twine or climb when they have support, and they carry sharp spines.

Tiny white flowers can show up in summer, but they are rare on indoor plants. After the flowers come small green berries that ripen to purple or black. Under the soil, the plant forms thick tuberous roots that fill a pot fast.

Types of asparagus fern

Several plants in the Asparagus genus share the name asparagus fern. Here are four of them:

• Common asparagus fern, also called plumosa fern or lace fern (Asparagus setaceus)
• Sprenger’s asparagus fern (Asparagus aethiopicus)
• Foxtail fern or plume asparagus (Asparagus densiflorus)
• Tree fern or tiki fern (Asparagus virgatus)

This guide covers the common asparagus fern. The others need similar care, but check the plant tag for size and light needs before you buy.

Light

Give asparagus fern bright, indirect light. Dappled light or a spot with a few hours of gentle sun works well. Strong direct sun burns the fine foliage. An east window or a spot a few feet back from a south or west window is a good place to start.

Yellow needles that drop often mean the plant has too little light or too little water. NC State notes that the yellow needles will not turn green again. Once you fix the problem, new stems grow up from the soil line. Cut the damaged stems right back to the base so the new growth has room.

In a dim home, a small LED grow light helps. My pendant grow light guide covers one easy option for a single plant.

Watering

Water on a steady schedule from spring to fall, then cut back in winter when growth slows. Water when the top inch of soil feels dry. Pour until water runs out the drainage holes, then empty the saucer.

Overwatering and poor drainage both cause yellow foliage and can lead to root rot. Underwatering also turns the needles yellow, so check the soil with a finger before you add water. Aim the spout at the soil and keep the foliage dry. Wet foliage and stale air can lead to leaf spot.

Temperature and humidity

NC State lists 55°F to 70°F (13°C to 21°C) as the preferred range for this plant. Normal room temperatures suit it. Keep it away from heat vents and cold drafts.

Asparagus fern likes high humidity. Dry air shows up as brown leaf tips. Run a humidifier in the room, or set the pot on a tray of pebbles and water so the pot sits above the waterline. Grouping plants together also helps.

In USDA zones 9 to 12 the plant can grow outdoors. In colder zones, you can move it outside to a shady spot for summer. Bring it back in before nights drop to about 55°F (13°C).

Potting mix and pots

Use a moist, well-drained, peaty potting mix. Asparagus fern likes soil on the acid side and rich in organic matter. A good indoor mix with some perlite works well. My guide on how to use perlite in potting mix explains how much to add.

Pick a pot with drainage holes. The tuberous roots fill a pot fast and can push the soil up. When that happens, move the plant to a pot one size larger, or divide it. Division is the easiest way to make new plants. Cut the root mass into sections with a clean knife and pot each piece on its own.

Fertilizing

A plant in a pot depends on you for nutrients. Feed it during spring and summer with a houseplant fertilizer. A slow-release product or a liquid feed both work. Follow the label rate and skip feeding in winter, when growth slows down.

Pruning

Trim only when you need to. NC State advises cutting stems all the way back to the roots rather than shortening them. You can also pinch the stem tips to keep the plant compact and push out new growth. Wear gloves for this job. The spines are sharp and the sap can irritate skin.

Pests and problems

Asparagus fern has few serious problems indoors. Watch for mealybugs, spider mites, and aphids, and for slugs if the pot spends summer outside. Check the undersides of the stems when you water. Wipe off small groups of pests, or treat larger problems with insecticidal soap. My post on tiny bugs in houseplant soil helps you sort out what you are seeing.

Most other problems trace back to care. Root rot comes from too much water or a pot without drainage. Leaf spot comes from wet foliage and poor air flow. Brown tips mean the air is too dry. Yellowing can come from too much water, too little water, or too little light.

Outdoors, deer tend to leave it alone. In warm places the plant can escape gardens, because birds eat the berries and spread the seeds. NC State notes it is listed as invasive in Australia, New Zealand, Cuba, and Hawaii, and Florida treats it as a species of caution.

Is asparagus fern toxic?

Yes. NC State lists the berries as poisonous to people and pets. Eating them can cause stomach pain, vomiting, and diarrhea. The sap can irritate skin. Keep the plant up high or in a room that children, cats, and dogs do not use.

Asparagus fern FAQs

Is asparagus fern a real fern?

No. Asparagus fern belongs to the asparagus family (Asparagaceae). It got its name because the feathery foliage looks like a fern.

Why is my asparagus fern turning yellow?

Yellow needles often mean too little light, too little water, too much water, or poor drainage. The yellow needles will not recover. Fix the care problem and new stems will grow from the soil line.

How much light does an asparagus fern need?

Bright, indirect light. Keep it out of strong direct sun, which burns the foliage.

Is asparagus fern safe for cats and dogs?

No. The berries are poisonous to pets and people, and the sap can irritate skin. Keep the plant out of reach.