How to Grow Cat Grass Indoors Without Mould: Australian Guide

Growing cat grass indoors gives your cat access to a controlled patch of greenery without relying on unknown outdoor plants. A soil-free kit can also reduce loose potting mix around the home and make it easier to monitor moisture.

Cat grass usually refers to young cereal grasses such as wheat, oat or barley grass. It is different from catnip. This guide explains how to grow it successfully in Australian homes and how to avoid the most common problems.

What you need

• cat grass seed from a reliable source;
• a clean growing container with drainage or a water reservoir;
• a suitable soil-free growing medium or mulch;
• fresh water;
• bright indirect light and airflow.

The MICHU Soil-Free Cat Grass Growing Kit includes Australian seed, mulch and a self-watering pot for convenient indoor growing.

Step 1: prepare the growing container

Wash and dry the container before use. Position the soil-free medium evenly so seeds have consistent contact with moisture. Avoid compressing the medium so tightly that air cannot circulate around developing roots.

Step 2: spread the seeds evenly

A dense clump of seed can stay wet and encourage mould. Spread a single, even layer according to the kit instructions. Replace unused seed in a cool, dry place.

Step 3: add water carefully

The goal is steady moisture, not saturation. In a self-watering system, add water to the reservoir as directed. If water sits directly around seeds with poor airflow, germination may become uneven.

Step 4: provide suitable light

Place the kit in bright indirect light. Harsh afternoon sun through an Australian window can heat a small container quickly and dry the shoots. Rotate the pot if the grass leans strongly towards one side.

Step 5: keep the water fresh

Once roots are established, refresh the water regularly. MICHU recommends changing water every one to two days after day seven to help keep the root area fresh. Growth speed will vary with season, room temperature and light.

How long does cat grass take to grow?

Many cat grass seeds begin germinating within several days and may be ready for supervised nibbling once the shoots are established. Follow the specific instructions supplied with the seed rather than using age alone.

How to grow cat grass without mould

Short answer: mould is most likely when seeds stay crowded, wet and poorly ventilated. Start with clean equipment, use only the recommended water level and allow air to move around the shoots. If a crop smells musty, becomes slimy or develops spreading fuzzy growth, discard it rather than trying to wash it clean.

1. Wash and dry the reusable container before every new crop.
2. Spread seeds in an even layer instead of piling them deeply.
3. Follow the kit’s water quantity and drainage directions.
4. Remove any germination cover when the instructions say to do so.
5. Place the pot in bright, indirect light with normal room airflow.
6. Refresh reservoir water as directed and do not leave it stagnant.
7. Do not apply household fungicides, fragrances or plant sprays to grass intended for a cat.

White root hairs or mould?

Fine root hairs are usually concentrated around the roots and appear as seeds establish. Mould may spread over seeds or growing material and can be accompanied by slime, discolouration or a musty smell. Photographs are not always enough to distinguish them. If uncertain, keep the grass away from your cat, discard the crop and restart with a clean container.

Can mouldy cat grass be saved?

Do not feed visibly mouldy grass or try to rinse the mould away. Reusing contaminated growing material can carry the problem into the next crop, so discard the affected grass and mulch, wash the container and begin again with a fresh refill.

Where to place cat grass

Choose a stable surface away from toxic houseplants. International Cat Care notes that cats may nibble grass and other herbs, while many common household plants can be toxic. Providing cat grass does not make unsafe plants suitable for a cat-accessible room.

The ASPCA lists cat grass as non-toxic, but any plant material can still cause gastrointestinal upset in some animals. Offer access in moderation and speak with your veterinarian if your cat eats excessive amounts or repeatedly vomits.

When should you replace the crop?

Replace grass when it becomes yellow, flattened, slimy, strongly odorous or difficult to keep fresh. Do not attempt to revive a mouldy crop. A cat grass seed and mulch refill lets you restart without replacing the pot.

For behaviour and safety context, read why cats eat grass.

Frequently asked questions

Is cat grass the same as lawn grass?

No. Cat grass is intentionally grown from selected cereal grass seed. Outdoor lawns may contain pesticides, fertilisers, parasites or unsafe plants.

Does cat grass prevent hairballs?

Evidence for specific health claims is limited. Treat cat grass as optional enrichment rather than a medical treatment.

Can kittens have cat grass?

Ask your veterinarian about the appropriate age and supervise access, particularly if a kitten tends to pull out and swallow seeds or growing material.

Sources: ASPCA cat grass listing and International Cat Care on plants and cats.