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spiny amaranth · Amaranthus spinosus

Why is my spiny amaranth growing so tall and thin?

Your spiny amaranth is stretching out because it is desperate for more light. Check your plant's location immediately to see if it is getting enough direct sun.

Not sure it's this? Check a photo of your plant for free

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

Check these first

  1. Observe the amount of direct sunlight hitting the plant throughout the day.
  2. Check if the plant is leaning toward a light source.
  3. Inspect the distance between leaf nodes on the main stem.

Likely causes

  1. Insufficient Light

    Most likely

    How to tell: The stems look weak and pale, with large gaps between the leaves. The plant is leaning heavily toward the nearest window.

    What to do: Move your plant to a spot that receives at least 6 to 8 hours of direct sunlight daily. If you cannot provide enough natural light, place it under a high output grow light for 12 hours a day.

  2. Excessive Nitrogen

    Possible

    How to tell: This is less common for this plant, but usually happens when you use a fertilizer too high in nitrogen. The plant grows very fast but the stems cannot support the weight.

    What to do: Switch to a balanced fertilizer with equal parts nitrogen, phosphorus, and potassium. Apply it at half strength once every 4 to 6 weeks during the growing season.

Leggy growth in other plants

Find out what's wrong with your spiny amaranth

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

You should worry if the stems become so weak they collapse under their own weight. It is normal for this plant to grow tall, but it should remain sturdy.

Stopping it coming back

Keep your plant in a bright, sunny location from the moment it sprouts to ensure thick, strong stems.

Spiny amaranth: leggy growth? Check yours with a photo

Every plant is a little different. Take a photo of your spiny amaranth 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 a leggy amaranth?
Yes, you can trim back the top of the plant to encourage bushier growth. Just be sure to provide more light afterward or it will just grow back thin.
Will my plant recover its shape?
The existing stems will not thicken up, but new growth will be stronger if you fix the light issue. You may want to stake the plant for support in the meantime.

More problems with spiny amaranth

Back to the spiny amaranth 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.