For our cat, we have some grass in flower pots on the windowsill. I don't have the package with the seeds any more, it said something with cat grass.

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On some of the blades, there is some white fluffy stuff:

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The soil is flower soil from the hardware store. I try to water the “plants” every day but sometimes forget. Sometimes they had a little too much water and were sitting in a little puddle that got soaked up eventually. The pots are directly next to the convection heater.

Is this something to worry about? Does it cause any health problems to us or the cat? Is there something that one can do against this?

2 Answers 2


Oh, perfect conditions for mould/fungal growth - dense foliage, warmth from a heater, wet soil along with, by the look of it, wet leaves as well, poor or no air movement. Cut out the affected areas, water when the surface of the soil is dry to the touch, water the soil in the pot, not the leaves, empty out water from the tray or container beneath after 30 minutes, open a window if possible to provide air flow. Not sure if eating mouldy leaves will affect the cat, but I suggest you remove them anyway,and keep checking to make sure the plant doesn't get worse, fungal infection can be difficult to get rid of once its started. Not sure I'd spray with any fungicide as its for the cat to eat, I certainly wouldn't spray it if it was my cat.

It might be worth splitting the grass to reduce foliage density in each pot - turn out of its pot, cut in half with a sharp knife of some sort (breadknife's the best), then replant the sections with fresh potting compost. Water in well.

  • I got enough flower soil and grass to start new grass pots. Perhaps that would be easier than trying to reduce the density? And then I should regularly cut the grass such that it is not that dense? Commented Nov 26, 2016 at 19:16
  • @MartinUeding Just take care when watering - don't wet the leaves,just the soil, don't leave it sitting in water, ever, for longer than 30 minutes, and you still need airflow round the plants - cutting them down frequently means the cat won't have grass to eat, they like to nibble long growths, so not really workable. if you reuse the same pots, wash them thoroughly with a brush in hot, soapy water. And why two pots? you only need one if you have even three cats...
    – Bamboo
    Commented Nov 26, 2016 at 19:45
  • I had watered the soil on top, lately I have watered the think below the pot such that it can soak it up. Letting it sit in water is an offence I commited, I probably overreacted after another pot dried up completely. And there are actually three pots for one cat, we just had those pots still in the basement so I used all and got some green in the living room. Commented Nov 26, 2016 at 20:08
  • @MartinUeding I am concerned that airflow might be an issue, so maybe cutting down half the plant and leaving the other half might help, not sure. And you're right, if a pot dries out completely, the only way to get it wet again is to sit it in water... As I recall though, this grass for cats doesn't last very long, couple of months maybe before it gives up for one reason or another which is a bit annoying because cats don't eat it all the time, just when they need to clear a fur ball.
    – Bamboo
    Commented Nov 26, 2016 at 20:28

Everything Bamboo replied is correctamundo! I just want to emphasize the air flow. Get the bottom of the pot off the surface of what it is sitting upon, remove the sitting water. All grasses at some point benefit from being cut back. I'd take all the foliage up in one hand, slightly twist, and with a partner and sharpened hedging shears cut down to 4". One chop with a few scissor trims looks super. Your grass looks very healthy and Bamboo is correct, cat grass or any grass indoors is not a long term perishable without a bit of knowledge and work. How long have you been growing this grass in these pots? They look very healthy and a teensy tiny bit of chewing is noticeable. How many cats have you got? This is not for nutrition. Cats are carnivores but grass helps with those dang fur balls and digestion, in tiny amounts. This is enough for 10 cats...grins!! When you water, water deeply and you HAVE to allow the soil to dry before watering again! No set schedule. If you chop off (mow so to speak) that top growth you'll get rid of a lot of that fungus. Not going to hurt your cats anyway but this is telling you there is way too much moisture and possibly too much fertilizer. Spraying fungicide is just not an option, there are safe solutions but even those aren't necessary. A small fan to blow the grass would be excellent. You need to see the blades of grass MOVING. Water deeply, then allow to dry out. You can also start new pots with clumps when you find it rootbound. You really only need one pot for the cats but I love the look of grasses, and yours are healthy. Consider a narrow, longer, shorter pot versus the round pots. No rock or gravel beneath the POTTING SOIL above the drain holes. Air between the surface and the bottom of your pot. Pull the blades of grass up like a pony tail to trim often, taking more than a third of any plant off is not a good thing. You can keep this going by dividing and replanting to include regular trimming and a little bit of high nitrogen fertilizer. No pesticides at all!! Not even necessary. A fan is. Check the roots after a month or so, if all you've got is a dense ball of roots, time to divide, wash your pot well, use new bagged soil and start again. What kind of cat do you have?

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