Indoor Asparagus: Growing and Caring

Botany and Description

Indoor Asparagus belongs to the botanical family Asparagaceae, a group of herbaceous and climbing plants that also includes edible species such as garden asparagus (Asparagus officinalis). Its genus name, Asparagus, comes from the ancient Greek “asparagos,” meaning young shoot, referring to the fine, branching stems characteristic of these plants.

Asparagus illustrations (circa 1920)

In French, Asparagus is often called indoor asparagus, ornamental asparagus, or even asparagus fern, although it is not a true fern. In its natural habitat, it is mainly found in South Africa and Asia, where it grows as climbing or bushy plants in bright, humid undergrowth. Its fine, airy foliage allows it to efficiently capture filtered light through the canopy.

Its popularity as a houseplant stems primarily from its light and elegant foliage, reminiscent of the delicacy of ferns, as well as its hardiness. It adapts well to domestic conditions, tolerates occasional watering lapses, and thrives in moderate light, making it an ideal choice for greenery enthusiasts, even beginners.

Among the most commonly cultivated species, Asparagus plumosus is undoubtedly the most prized for its finely divided, almost feathery foliage, which adds an airy touch to any interior. On the other hand, Asparagus sprengeri, sometimes called “florist’s asparagus,” is more often used in hanging arrangements for its cascading habit and rapid growth. Other species like Asparagus densiflorus and Asparagus setaceus are also popular, each offering a unique variation of this light and graceful foliage.

The very discreet flowering of Asparagus setaceus

Asparagus plumosus

Asparagus plumosus adopts a gracefully upright silhouette when young, but over time it develops twining and climbing stems, capable of clinging to a support if provided. Its stems, fine and flexible, extend into an airy tangle, giving the plant an ethereal appearance.

At the base, a fleshy and fibrous root system develops in the form of tubers, allowing it to store water and withstand short periods of drought. Unlike trees or shrubs, it does not have a true trunk; its stems emerge directly from the base and branch abundantly.

The foliage of Asparagus plumosus is actually made up of cladodes, false leaves in the form of ultra-fine needles that unfold by the thousands, forming a light and airy ensemble. This almost feathery appearance has earned it its name. In spring or summer, it may produce tiny white or greenish flowers, very discreet but fragrant, which sometimes give way to small spherical berries, green then black when ripe.

Asparagus plumosus (© Forest and Kim Starr)

Asparagus sprengeri

Asparagus sprengeri, on the other hand, displays a more arched and cascading habit. Rather than climbing, it develops in soft clumps that flow in elegant cascades, making it a perfect plant for hanging baskets or pot edges. Its stems are thicker and stiffer than those of plumosus, though they retain some flexibility.

Again, the fleshy roots allow the plant to survive irregular growing conditions.

Its foliage, although similar to that of plumosus, is also slightly coarser, with slightly more spaced cladodes and a more pronounced bright green hue. When it flowers, it produces small whitish flowers, often followed by bright red berries, adding an extra ornamental touch.

On the left, Asparagus sprengeri (©Forest and Kim Starr). Top right, Asparagus setaceus and bottom right Asparagus densiflorus Myersii

When and how to plant an indoor Asparagus in a pot?

Indoor Asparagus is best planted in spring, the ideal time to allow it to adapt to its new environment and benefit from active growth. However, it can be planted at other times of the year, provided extreme cold or excessive heat is avoided.

The ideal substrate

An Asparagus thrives in a light, well-draining, and slightly humus-rich substrate. A mix of houseplant compost, sand, or perlite for drainage, along with a bit of compost or peat to maintain good water retention, is perfect. The goal is to avoid overly compact soil, which could suffocate its tuberous roots.

Where to place it?

Asparagus prefers soft, indirect light, so it appreciates a bright spot without direct sunlight, which could scorch its delicate foliage. An east or west-facing exposure is ideal, although it tolerates partial shade. It can handle heated interiors but prefers a temperature between 15 and 25°C, with moderate to high ambient humidity. In overly dry air, its cladodes yellow and drop more easily. To prevent this, regular misting with non-calcareous water or using a humidifier can be beneficial.

Which pot to choose?

Asparagus develops a strong, tuberous root system that can quickly fill its pot. It’s important to choose a wide and deep pot, at least 20 to 25 cm in diameter for a young plant, and opt for a breathable material like terracotta, which helps evaporate excess moisture. A plastic pot also works but retains more water, requiring careful watering adjustments. Always ensure it has drainage holes to prevent waterlogging.

Steps for planting Asparagus in a pot

1. Prepare the pot: place a layer of clay pebbles or gravel at the bottom to improve drainage.
2. Fill with substrate: mix your compost with sand or perlite, then pour some into the pot.
3. Position the plant: gently remove the Asparagus from its original pot. If the roots are too dense, gently loosen them with your fingers.
4. Place and firm: position the plant in the centre and add substrate around it to cover the roots. Press lightly to stabilise without compacting too much.
5. Water moderately: water generously right after planting, then let the surface of the compost dry slightly before the next watering.

Repotting Asparagus

Asparagus is a fast-growing plant, so it requires repotting every 1 to 2 years, usually in spring. The need for repotting is evident when roots emerge from the drainage holes or growth slows despite good growing conditions. When repotting, follow the same steps as planting, choosing a slightly larger pot (2-3 cm wider in diameter) and refreshing part of the substrate to provide fresh nutrients.

Nota bene: if the plant becomes too large, this is also an opportunity to divide the root ball by carefully cutting sections of tuberous roots, each with a few stems, to create multiple plants.

Cultivation and Care of Asparagus

The indoor Asparagus is a robust and easy-to-care-for plant, but regular maintenance will help it maintain its beautiful, airy foliage and vitality.

Watering: Finding the Right Balance

The Asparagus prefers a slightly moist but never waterlogged substrate. Its tuberous root system allows it to store water, making it tolerant of occasional missed waterings.

• In spring and summer, during active growth, water approximately once or twice a week, allowing the surface of the soil to dry out between waterings.
• In autumn and winter, reduce the frequency to once every 10 to 15 days, as the plant enters dormancy and consumes less water.

The watering water should be non-calcareous and at room temperature, ideally rainwater or filtered water. Avoid stagnant water in the saucer, as it promotes root rot.

Fertilisation: Giving Growth a Boost

A nutrient supply helps the Asparagus maintain dense, vibrant green foliage.

• From March to September, add a liquid fertiliser for green plants every 2 to 3 weeks.
• In winter, fertilisation can be stopped or reduced to once a month if the plant continues to grow slightly.

If your Asparagus turns yellow despite proper watering, a lack of nutrients may be the cause. In this case, more regular fertilisation or repotting with fresh substrate can restore its vigour.

Pruning: Is It Necessary?

The Asparagus does not require strict pruning, but light maintenance helps keep it looking tidy.

• Cut dry or yellowed stems at the base to encourage new growth.
• To control its growth or give it a more compact shape, you can trim some stems in spring. The plant tolerates pruning well and will quickly regrow.
• For climbing varieties like Asparagus plumosus, you can guide the stems onto a support or shorten them if they become too invasive.

Precautions and Points to Watch

• Beware of dry air: The Asparagus does not tolerate overly dry environments, especially in winter with heating. Regular misting or a humidifier will help it maintain lush foliage.
• Avoid direct sunlight: Excessive exposure can cause burns on the cladodes.
• Watch out for cold drafts: It dislikes temperatures below 10°C.
• Handle with care: Some varieties, like Asparagus sprengeri, have tiny spines on their stems that can irritate the skin.

→ Read also: Indoor Asparagus: How to Care for It Season by Season?

Asparagus setaceus

Potential Pests and Diseases of Indoor Asparagus Ferns

Asparagus is a robust and relatively hardy plant, but it can still fall victim to a few pests and diseases, especially indoors where dry air and poor air circulation can encourage certain problems.

The most common pests

• Spider mites: these tiny mites appear mainly when the air is too dry. They cause yellowing of the foliage and the formation of fine webs under the stems. To avoid them, it is essential to increase ambient humidity by misting the foliage with water or placing a container of water nearby. In case of infestation, wiping the leaves with a damp cloth and spraying with soapy water can be effective.

• Mealybugs: they form small cottony clusters at the base of the stems or under the cladodes. These pests suck the sap and weaken the plant. To eliminate them, use a cotton swab soaked in 70° alcohol or apply a natural treatment based on diluted black soap.

• Aphids: less common, they sometimes settle on new shoots. They can be removed with a strong jet of water or a mixture of water and black soap.

• Thrips: these tiny insects leave silvery spots on the leaves and weaken the plant. A simple daily spray of non-calcareous water can help get rid of them.

Possible diseases

• Root rot: this is the most common problem, usually caused by overwatering or poor substrate drainage. The tuberous roots rot and the plant quickly withers. To avoid this, water moderately and ensure the pot has drainage holes. If the roots are affected, repot the Asparagus in dry substrate after cutting away the rotten parts.

• Leaf spots and yellowing: brown or yellow spots may appear if the plant is exposed to direct sunlight, if the air is too dry, or if it suffers from a lack of nutrients. Balanced fertilisation and good management of ambient humidity can help limit this problem.

• Mould and fungi: excess moisture and poor air circulation can encourage the growth of mould on the substrate or stems. If this occurs, reduce watering and ventilate the room to improve the plant’s environment.

Prevention and good practices

• Ventilate the room regularly to avoid diseases related to stagnant humidity.
• Check the foliage and the base of the stems from time to time to spot pests as soon as they appear.
• Avoid overwatering and use a well-draining substrate to prevent root rot.
• Clean the foliage with a damp cloth from time to time to remove dust and limit pest attacks.

How to propagate Asparagus?

Asparagus can be propagated in two main ways: by dividing the tuberous roots and by sowing seeds. Division is the simplest and quickest method, while sowing requires more patience.

Dividing the clumps (the easiest and quickest method)

Division is the ideal technique for propagating an Asparagus while rejuvenating a plant that has become too dense in its pot. It is best done in spring, during repotting, when the plant resumes its growth.

Steps to follow:

1. Remove the plant from the pot: gently remove the Asparagus from its pot by tapping the sides to free the roots without damaging them.
2. Separate the clumps: using your hands or a sharp knife, divide the root ball into several sections. Each section should contain tuberous roots and several healthy stems.
3. Repot each section: place each division in a new pot with a fresh, light, and well-draining substrate.
4. Water lightly: moderate watering will help the plant settle in without risking root rot.

The new plants will quickly resume growth and develop beautiful foliage within a few weeks.

Sowing seeds (a long and delicate method)

Propagation by sowing is possible if the Asparagus has produced red or black berries, which contain seeds. This method takes more time, as the seeds take several weeks to germinate, and the plant will take several months, or even years, to reach a good size.

How to sow Asparagus?

1. Harvest the seeds: once the berries are ripe (red or black), collect the seeds by cleaning them thoroughly under water.
2. Soak the seeds: let them soak for 24 hours in lukewarm water to soften their coating and facilitate germination.
3. Prepare the substrate: use a mixture of light and sandy compost to ensure good drainage.
4. Sow on the surface: place the seeds on the surface of the compost and cover them with a thin layer of substrate.
5. Maintain moisture and warmth: water lightly and place the pot in a warm (20-25°C) and bright spot, out of direct sunlight. Covering the pot with plastic wrap or a mini greenhouse helps retain moisture.
6. Patience! Germination can take 3 to 6 weeks, sometimes longer. Once the seedlings are well developed, they can be transplanted individually.

Indoor Asparagus Fern: Where and How to Showcase It?

With its airy and delicate foliage, Asparagus adapts to various interior styles, adding a touch of elegant and light nature. It particularly suits bohemian, Scandinavian, tropical, and vintage atmospheres, but it can also blend into more modern décors thanks to its graphic appeal.

Where to place it for a beautiful display?

• High up or suspended: trailing varieties like Asparagus sprengeri are stunning in hanging baskets or on wall shelves, where their foliage can cascade freely.
• On a piece of furniture or a bright windowsill: Asparagus plumosus, with its gracefully arched stems, will find its place on a console, dresser, or bookshelf, adding a touch of greenery without overwhelming the space.
• In an open terrarium: its fine and light appearance makes it an excellent candidate for an open terrarium, where it can coexist with other tropical plants like fittonias and mosses.

Asparagus setaceus, Asparagus sprengeri, and kokedama of Asparagus plumosus (© Gergely Hideg)

Which pot to choose to enhance it?

• A raw terracotta pot: perfect for a bohemian, rustic, or Mediterranean style. It also has the advantage of promoting good drainage.
• A ceramic pot in neutral tones (white, beige, light grey): ideal for a Scandinavian or minimalist interior, highlighting the delicate texture of its foliage.
• A wicker or rattan planter: perfect for a natural and warm ambiance.
• A macramé hanging pot: enhances the airy aspect of Asparagus, especially for trailing varieties.
• A glass terrarium: for a more contemporary or urban jungle look, Asparagus plumosus can be grown in a large open terrarium, where its fine foliage will create a magical effect.