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Johnsongrass · Sorghum halepense

Why is my Johnsongrass looking so tall and thin?

It is less common for Johnsongrass to get leggy, as it is a vigorous grower, but it happens when the plant does not get enough light. Check your light levels first to see if the plant is reaching for the sun.

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leggy growth on a plant
Photo: Rosser1954, CC BY-SA 4.0

Check these first

  1. Move the plant to a brighter location.
  2. Check if the plant is crowded by other pots.
  3. Rotate the pot weekly to ensure even growth.

Likely causes

  1. Insufficient Light

    Possible

    How to tell: The stems will be long and weak with large gaps between the leaves. The plant will lean heavily toward the nearest light source.

    What to do: Move the plant to a spot that receives full, direct sun for at least 6 to 8 hours a day. If you are growing indoors, place it right in a south facing window.

  2. Overcrowding

    Possible

    How to tell: Multiple plants growing in the same container will compete for light and nutrients. This causes them to grow tall and spindly instead of bushy.

    What to do: Thin out the seedlings or divide the plant into separate pots. Give each plant at least 12 inches of space to grow properly.

Leggy growth in other plants

Find out what's wrong with your johnsongrass

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

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When to worry

It is normal for this grass to grow tall, but it should not be weak or floppy. If the stems cannot support themselves, it is time to adjust the light.

Stopping it coming back

Provide plenty of direct sunlight from the start. Ensure the plant has enough room to spread its roots and foliage.

Johnsongrass: leggy growth? Check yours with a photo

Every plant is a little different. Take a photo of your johnsongrass and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

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Questions people ask

Can I prune the tall stems?
Yes, you can trim back the stems to encourage bushier growth. Just make sure it still gets enough light after pruning.
Will it get bushy again?
Once you provide more light, new growth will be stronger and more compact. The old leggy stems will likely remain thin.

More problems with Johnsongrass

Back to the Johnsongrass guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.