Selaginella Care Guide

Selaginella, commonly known as spike moss, is a plant that likes its surroundings consistently humid. Give it moist air and lightly damp compost and it will grow into a soft, moss-like carpet of tiny scale-shaped leaves. Let it dry out, however, and its delicate fronds can crisp up surprisingly quickly.

Despite the name, Selaginella is neither a true fern nor a true moss. It belongs to the lycophytes, an ancient group of plants with a history stretching back hundreds of millions of years. For modern houseplant growers, though, the important bit is much simpler: spike moss does best when it stays humid and never gets completely dry.

In this guide, we’ll cover everything you need to know about Selaginella care, from light and watering to soil, repotting and propagation, along with some of the spike moss varieties we grow and the common problems to look out for.

Light Requirements

Low to medium, indirect light is best for Selaginella. Selaginella grows on shaded forest floors, so it wants bright shade rather than sun. An interior spot a couple of metres from a window, or a north-facing sill, suits it well. Too much light bleaches and scorches the delicate foliage; too little and growth thins out. The iridescent blue-green types such as the Peacock Fern hold their shimmer best in soft, even light.

How Often to Water Spike Moss

Our key to success with Selaginella is keeping the compost lightly and consistently moist, never wet and never dry. Check every couple of days and water as soon as the surface starts to feel dry to the touch. Spike moss has shallow roots and no tolerance for drought, so a single missed watering in a dry room can brown the fronds.

Signs of underwatering include curling, browning, crisping fronds, often starting at the tips. Signs of overwatering can show through yellowing and mushy, blackened patches where water has pooled and stagnated. Aim for the feel of a wrung-out sponge. Tepid rainwater or filtered water is kinder than hard tap water if you have it.

Humidity

This is the part that makes or breaks spike moss. It needs high humidity, comfortably above 60 per cent, which is more than most UK living rooms provide. The plants are small and slow, which makes them ideal candidates for an enclosed environment. A terrarium is the single best home for most Selaginella; the glass holds the moisture they crave and the compact size means they will not outgrow it. Failing that, a naturally humid room like a bathroom, or grouping plants together on a pebble tray, will help. We do not recommend misting: it raises humidity only for minutes and can encourage fungal problems on dense foliage.

Soil and Potting Mix

Selaginella does best in a moisture-retentive mix that stays lightly damp without becoming waterlogged. We recommend using our ABG Potting Mix, which is designed to hold moisture while still providing enough aeration around the roots.

The mix is particularly well suited to humidity-loving plants like spike moss, helping the compost stay evenly moist without becoming heavy or compacted. Avoid gritty, fast-draining cactus or succulent mixes, as these can dry out too quickly for a plant that is particularly sensitive to drought.

Repotting

Spike moss is slow and stays small, so it rarely needs moving on. Repot only when it has clearly filled its pot, in spring, into a shallow container barely larger than the last. A wide, shallow pot suits the creeping, mat-forming habit better than a deep one. Keep it in proportion: an oversized pot holds too much wet compost around the small root system.

Propagation

Spike moss propagates easily by division or by stem cuttings, which is part of its charm:

• Division: at repotting, gently pull the mat into smaller clumps, each with roots attached, and pot up separately.
• Cuttings: lay short lengths of stem onto damp compost and keep them enclosed and humid. The creeping stems root readily where they touch moist substrate.

Enclosing cuttings in a covered tray or propagator keeps the humidity high while they establish, which is exactly the environment these plants want anyway.

Spike Moss Varieties Worth Knowing

We propagate a good range in our nursery, and they vary more than people expect:

• Selaginella uncinata, the Peacock Fern, forms creeping mats with an iridescent blue-green sheen.
• Selaginella martensii 'Jori' is a more upright, branching type that builds into a small bushy plant.
• Selaginella serpens is a tiny-leaved creeper, ideal for terrariums.

The full selection sits in our Selaginella collection. Most are pet-friendly, which makes them a useful choice for homes with cats and dogs.

Common Problems when growing Spike Moss

Crispy, browning fronds

Crispy or browning fronds are one of the most common problems with Selaginella. They usually mean the plant has become too dry, either because the compost has dried out or the surrounding air is lacking humidity. Spike moss has very shallow roots and delicate foliage, so it can react quickly when conditions change.

Check the compost first. If the surface feels dry, give the plant a thorough drink and allow the excess water to drain away. Going forward, aim to keep the mix consistently lightly moist rather than letting it dry out completely. Increasing humidity is just as important, particularly in centrally heated homes where the air can become surprisingly dry during winter.

If your home is naturally dry, an enclosed setup such as a terrarium, cabinet or humidity case can make a big difference. These create a more stable environment and reduce the amount of moisture the plant loses through its tiny leaves.

Unfortunately, damaged fronds will not turn green again once they have completely crisped up. You can trim away the worst affected growth with clean scissors and focus on improving the conditions. With the right care, healthy new growth should gradually fill back in.

Yellowing or soft patches

Yellowing leaves and soft, waterlogged-looking patches can indicate that the plant is staying too wet. This can happen when the compost remains saturated for too long, particularly in a container with poor drainage, or when water sits on the foliage without enough airflow.

Check that the pot has drainage holes and that excess water can escape freely. If the compost is staying wet for a long time, allow it to dry slightly before watering again, while still avoiding letting the plant become completely dry. Improving airflow around the plant can also help, especially in an enclosed setup.

Fading colour

Some Selaginella varieties have beautiful iridescent or metallic colouring, but too much direct sunlight can cause these colours to fade. If your plant is losing its usual sheen, look at where it is sitting and consider whether it is receiving stronger light than it needs.

Bright, indirect light is generally a better choice. Keep it away from intense midday sun, particularly through glass, where the heat and light can build up quickly.

Problems in winter

Winter can be a particularly tricky time for Selaginella. The combination of shorter days, lower natural humidity and central heating can create conditions that are very different from the consistently humid environment the plant prefers. This is when we most often hear from customers whose spike moss has started to crisp or lose its colour.

If yours is struggling during the colder months, check the compost and humidity before making any major changes to its care. Moving it into a more enclosed, humid environment is often the simplest way to create the stable conditions it needs.

If you're unsure what is causing a problem with your Selaginella, we're always happy to help you work out what is going on and adjust its care.

Selaginella is a little less forgiving than your average houseplant, but once you understand what it wants, its care is fairly straightforward. Keep the compost lightly moist, give it bright indirect light and, most importantly, keep humidity high.

If you can provide those conditions, spike moss will reward you with fresh, delicate growth and that wonderfully soft, moss-like appearance that makes Selaginella such a lovely addition to a terrarium or humid plant collection.