
I’ve already posted two variations of instructions on how to grow cat grass, each with supply substitutions (cat and cat grass and cat and cat grass 2.0). Now, with apologies, here’s a third version. This one mitigates against mold and rust issues.
After numerous rounds of growing and adjusting, I concluded that mold tends to grow more easily if there are ungerminated seeds left by Day 2. To remove them, it’s easier to use two mason jars; during transfer to the second, smaller jar on Day 2, I use a teaspoon to separate out sprouting and dead seeds. The sprouting seeds tend to clump with each other, so it’s not as tedious as it may sound.
I also discovered that the metal frog lid I’d been using develops rust over time. It became a losing battle, attempting to remove the rust after each growing cycle. I searched far and wide for a substitute. The best I could manage to date is a mason jar toothbrush lid made of 304-grade stainless steel. I will update this if I find anything better.
Grow Cat Grass 3.0!
Supply List
- cat grass seeds
- water
- measuring teaspoon
- tableware-type teaspoon or chopstick
- 16-oz. wide-mouth mason jar
- 8-oz. wide-mouth mason jar
- canning lid
- sprouting lid
- supposedly rust-resistant stainless steel mason jar toothbrush lid (if your cat likes to pull out grass)
- dish or bowl to put draining jar in
- spray bottle
Instructions
Day 0


On the morning of Day 0, place two (2) teaspoons of seeds in the 16-oz. wide-mouth mason jar.
Add enough water to ensure that all the seeds have the opportunity to be saturated.


Set the canning lid (without the screwing part of the lid) on top of the jar, leaving a slight gap for air flow. This theoretically keeps out contaminants, but it may not be necessary.
Place jar out of direct sunlight, and avoid extreme temperatures. Complete blackout is unnecessary. I place it on the kitchen counter.

On the evening of Day 0, approximately 12 hours later, replace the canning lid with the sprouting lid and drain off the water. Then rinse and drain the seeds in fresh water 2-3 times.
Place jar upside down on the dish or bowl, allowing any excess water to continue to drain off.
Again place jar out of direct sunlight, and avoid extreme temperatures. Complete blackout is unnecessary.
Day 1
On the morning (24 hours) and evening (36 hours) of Day 1, rinse and drain the seeds in fresh water 2-3 times.
Day 2
By the morning of Day 2 (48 hours), rinse and drain the seeds in fresh water 2-3 times. Then, with help of a teaspoon or chopstick, transfer the sprouted seeds to the 8-oz. mason jar. Remove any unsprouted seeds you see. The sprouted seeds tend to hold onto each other via their roots, leaving behind lone, unsprouted seeds.


I found that the shape of the tall 16-oz. jar compared to the squat 16-oz. jar I used in Grow Cat Grass 1.0 made it easier to spot and remove unsprouted seeds.
Set the canning lid on top of the 8-oz. jar, leaving a slight gap for air flow. This theoretically keeps out contaminants, and may also decrease water evaporation so the seeds don’t dry out.
Place jar out of direct sunlight, and avoid extreme temperatures.
In the evening of Day 2 (60 hours), use sprayer and spritz seeds lightly with water. I skip draining as the seed roots aren’t tangled enough to prevent the seeds from slipping out.
Replace canning lid and leave jar somewhere out of direct sunlight, and avoid extreme temperatures.
Day 3
On the morning of Day 3 (72 hours), use sprayer and spritz seeds. By now, seed roots are more tangled with each other, so you can water more vigorously, spritzing liberally and then draining off excess water.
Replace canning lid and expose the jar to more light, closer to a window or under grow lights. Avoid extreme temperatures. I rotate the jar periodically so the rapidly growing grass blades grow straight.


By late afternoon or evening of Day 3 (76-84 hours), the grass has typically grown long enough that it’s time to attach the toothbrush lid. This is only if your cat likes to pull grass out rather than just nibble on the tips.
Spritz and drain liberally, giving the seeds a thorough rinsing, before attaching the lid.
Set the jar close to a window, as before.
Day 4-6





Use sprayer in morning and evening, to spritz grass with water. I invert the jar when spritzing so excess water drips off.
By the evening of Day 5 or morning of Day 6, grass is long enough to present to my cat.
Continue to spritz the grass for the remainder of the grass’ life, and keep an eye out for any mold growth at the roots. Toss the grass out if you see mold. I usually compost it sometime between Day 9 and Day 12.
I typically start a new batch every fourth day to ensure that my cat will almost always have fresh grass to munch on.