My Chestnut / White Kit Is Only Growing One Mushroom?

A single early mushroom is called a "pre crop" and is completely normal. Here is what to do about it and how to ensure a full crop follows.

Quick Diagnosis

Single mushroom appeared early? This is a pre crop

Pick it now, including the entire root

Full crop follows in 1-2 weeks

Root left behind? Remove it immediately

What Is a Pre Crop?

A pre crop is when one or two mushrooms push through earlier than the rest. It happens because each kit is a living product. The mycelium does not always colonise the substrate in a perfectly uniform way, so some areas are ready to fruit slightly ahead of others.

This is completely normal and not a sign that something has gone wrong. In ideal conditions, between 14-21°C and ideally around 17-18°C, the predicted window for a full crop is 16-24 days. A pre crop can appear before this window opens, which is simply the kit getting a head start in one spot.

Do not leave it growing. A lone mushroom left in place will continue drawing energy and nutrients from the substrate, suppressing the rest of the crop. The longer it stays, the more it delays the full flush.

How to Pick the Pre Crop Correctly

The way you remove the mushroom matters. If the root is left behind in the topsoil, it will block new growth from coming up through that spot and can cause the kit to stall.

Picking Steps:

Grip the mushroom at its base, right where the stem meets the topsoil
Twist and pull gently to bring the entire mushroom out, root and all
Check the bottom for a white clump of root material attached
If root is still visible in the topsoil, pinch it out with fingers or tweezers

Do not cut with a knife. Cutting leaves the root behind in the topsoil. Always twist and pull so the root comes out cleanly with the mushroom.

What a correct pick looks like: You should see a small white clump of root material attached to the base of the mushroom. This means the entire root came out cleanly and the topsoil is clear for new growth.

A picked mushroom held in hand showing the white root clump still attached to the base of the stem

A correctly picked mushroom with the root still attached - this is what you want to see

A single pre crop mushroom growing from a Chestnut or White mushroom kit

A single pre crop mushroom - pick this as soon as it has grown

Mushroom root left behind in the topsoil which needs to be removed

Root left in the topsoil - remove this to allow new growth

After Picking: Getting the Full Crop Through

Once the pre crop is removed, continue caring for the kit as normal. A fuller crop should appear within 1-2 weeks. Check the following conditions to give the next flush the best chance.

Temperature: Keep between 14-21°C, ideally 17-18°C. Avoid radiators, direct sunlight, and rooms with big temperature swings.

Topsoil hydration: The topsoil should be a consistent deep black colour with no dry patches or grey speckles. Spray little and often, paying attention to the edges which dry out first. See the topsoil hydration guide if it has dried out.

Location: Not in a cupboard, wardrobe, or cabinet. The kit needs indirect light and some natural airflow. Make sure the side flaps are raised up.

Patience: Give the mycelium 1-2 weeks to regroup. Resist the temptation to move the kit around or change conditions. Consistency is what the mycelium responds to best.

What If It Happens Again?

If the kit produces another lone mushroom after you have picked the first one, the approach is the same: pick it cleanly, remove the root, and wait. Some kits will send up one or two early scouts before committing to a full flush. As long as the topsoil is properly hydrated and the temperature is right, the main crop will follow.

Still no full crop after 2-3 weeks of correct care? Get in touch with the Merryhill Mushrooms support team. Send a photo of the kit and a description of your setup (room, temperature, misting routine) and we can advise on next steps.

Essential Checklist

Pick the pre crop as soon as it has grown, do not leave it

Twist and pull to remove the entire root, never cut with a knife

If root is left in the topsoil, remove it immediately

Temperature between 14-21°C, ideally 17-18°C

Topsoil deep black, damp, no dry edges or grey patches

Side flaps raised, indirect light, some natural airflow

Allow 1-2 weeks after picking for full crop to appear

Common Mistakes

Leaving the pre crop to keep growing

Cutting instead of twisting, leaves root behind

Temperature outside 14-21°C

Topsoil drying out, especially at the edges

Frequently Asked Questions

Is a pre crop a sign that something is wrong with my kit?

No. A pre crop is completely normal. Each kit is a living product and the mycelium does not always colonise the substrate uniformly. Some areas are ready to fruit slightly ahead of others. As long as you pick it promptly and remove the root, a fuller crop should follow within one to two weeks.

What happens if I leave the pre crop growing?

The lone mushroom will continue drawing energy and nutrients from the substrate, which suppresses new growth across the rest of the kit. The longer it stays, the more it delays the full flush. Pick it as soon as it has reached a reasonable size.

I already cut the mushroom with a knife. Is that a problem?

Cutting can leave the root behind in the topsoil, which blocks new growth from that spot. Check the area where the mushroom was growing. If you can see a small white stump or root material, pinch it out gently with your fingers or tweezers. Once the root is removed, the kit should recover normally.

How do I know if my topsoil is hydrated correctly?

The topsoil should be a consistent deep black colour, damp to the touch, with no standing water. If it is lightening, showing grey patches, or pulling away from the edges, it has dried out and needs rehydrating. The topsoil hydration guide covers this in detail with photos showing exactly what correct hydration looks like.

What temperature should my Chestnut or White kit be kept at?

Keep the kit between 14 and 21°C, with 17 to 18°C being the sweet spot. Avoid placing it near radiators, in direct sunlight, or anywhere with significant temperature swings throughout the day. Kitchens, utility rooms, and spare bedrooms tend to work well in most UK homes.

My kit has not produced anything after 24 days. What should I do?

Check the full growing instructions and make sure the topsoil is properly hydrated, the temperature is within range, and the kit is not in an enclosed space. If everything looks correct and there is still no growth after three weeks of proper care, contact the Merryhill Mushrooms support team with a photo and we will help.

Can I get more than one crop from my kit?

Yes. Most Chestnut and White kits produce at least two flushes, and some manage three. After each harvest, rest the kit for a few days, then resume your normal misting routine. The second flush is usually smaller than the first but still produces a worthwhile harvest. For a full breakdown of what to expect, see mushroom growing kit yields compared.