Can Guinea Pigs Eat Grass Instead Of Hay?

As a guinea pig owner you may know, How much hay your guinea pigs need every day. So, you may decide to replace it with grass sometimes for many reasons. But, Can guinea pigs eat fresh grass instead of hay?

Guinea pigs can eat fresh grass in addition to hay or instead of hay occasionally when you run out of hay. But, the need for hay cannot be met by grass for a long time due to the quantity, quality, and availability of grass. Hay constitutes a major part of guinea pigs’ diet and they can’t survive without it. So, you need to feed dried grass or hay and shouldn’t feed fresh grass as the substitute for hay.

So, you should provide them with ideal hay as quickly as possible to prevent any complications.

But, why is it so important to not replace hay with grass, though both are almost similar?

Let’s check out the difference between hay and grass for guinea pigs and find out when you can feed your guinea pig grass instead of hay.

You can also check out my other articles on the best alternatives to hay.

Is Grass the same as hay for guinea pigs?

Can you feed Guinea grass instead of hay

Hay is a special form of grass and other herbaceous plants processed for guinea pigs and other pets whereas grass is the plant with its original form. Hay is the grass that’s cut, dried, stored, prepared, and stored for small pets such as guinea pigs. On the other hand, fresh grass that you find outside on your lawn or garden doesn’t go through this process.

Since guinea pig’s digestive systems can have a lot of forage, it’s normal that they eat and like hay as well as fresh grass. However, every grass isn’t safe for their health.

Why can’t grass replace hay for guinea pigs?

Check out the difference between grass and hay in a guinea pig’s diet and know why you shouldn’t use hay instead of grass.


Hay can be a mix of different types of grasses or other herbaceous plants. Usually, guinea pigs eat timothy, orchard grass, or oat hay. On the other hand, grass is the main form of the plant.


Hay is readily available. You can get the hay in any pet store or also order online at any time. But, you may not get fresh grass if you don’t have a lawn or garden at home.

Even if you have a lawn, you may not be able to feed your piggies fresh grass because of the types of the condition of the grass. Besides, it’s also tough to provide a large amount of fresh grass instead of hay to your guinea pigs for months.

Working as guinea pig’s food

Hay is manufactured for small pets like guinea pigs and it’s the primary food for them. They will need unlimited hay regularly to maintain their body and because it is disease-free.

Moreover, an indoor guinea pig’s digestive system requires hay (80% of their total diet) more than anything to do proper function. So, hay is the most important food for your little piggies.

On the other hand, fresh can also work great as guinea pig food if you can maintain the quality. But, it may not be a good idea to use it as the main food.

However, both hay and fresh grass contain abrasive silica that prevents teeth from getting too long.

Effect from overeating

Overeating isn’t good for your little piggies. However, eating more than the required amount of fresh grass may upset their little tummy such as diarrhea or bloating, whereas hay may not cause any problem at all. 

Safety for health

All grasses may not be safe and good for guinea pigs while hay that’s recommended for guinea pigs is safe and the best food for them.

This becomes a problem when you decide to give them grass from a lawn. Lawn grass is treated chemically and contains weeds, grass clipping, animal poops or urine, and bird droppings.

Wet grass causes skin infections and gut issues. But, good-quality hay doesn’t have any of these problems.

Grass clippings are also harmful to the guinea pig’s tummy, that’s not an issue with hay.

If the grass has poop or urine of any animal like dogs or cats and birds dropping, it can be dangerous for guinea pigs.

The necessity of regular deworming

Fresh grass and soil normally contain the parasite’s eggs. So, your guinea pigs may be exposed to worm infections.

That’s why guinea pigs will need regular deworming if they eat grass frequently. But, hay is completely free of intestinal parasites.

Fertilizers and pesticides

Fresh grass from the lawn or outside may contain various chemicals, pesticides, or fertilizers. It can risk the life of your guinea pigs.

Nutritional value

Hay and fresh grass contain almost similar nutrients that a guinea pig needs. However, hay has more nutritional value than fresh grass. Both hay and fresh grass provide high fibers, vitamins, and minerals.

They boost the immunity of your piggies and help fight different diseases, reduce inflammation and also speed up the recovery process from an injury.

They have fewer amounts of carbs or sugars. So, they won’t increase the sugar level of your guinea pigs. Moreover, hay and grass also reduce the cholesterol that’s bad for the body.

Check out the best substitutes for timothy hay.

When can guinea pigs eat grass instead of hay?

You can only choose fresh grass instead of hay when hay isn’t available to you. Sometimes, you may run out of hay and don’t get any new products immediately. Though hay is available online or at local pet stores, sometimes there may be delays in delivery.

In those situations, you have to provide them with fresh grass. But, make sure it doesn’t last very long, maybe not more than 1-2 days.

In most cases, I see that, when an owner runs out of hay, they try to offer them grass that may not be appropriate for them. So, you should get yourself ready for that moment.

When you own a guinea pig, you should know about all the alternative supplies that can be helpful for your guinea pigs someday.

So, you can grow fresh grass in your yard or know where you can find good quality grass near your residence. Maybe you may contact a nearby farm.

Another situation is when you have hay but it’s not in the required quantity. Fresh grass can meet the daily requirements of nutrition in that case.

However, you always can provide fresh grass to your guinea pigs in addition to a hay diet. It’s good for their taste and health.

Some owners use fresh grass instead of hay regularly. But, they had to ensure the quality of the grass and take a good look at the guinea pig’s health. If you plan to do that, you must ensure that, though I will strongly suggest you must go for hay as the primary diet.

Now you may wonder, what types of grass and its quality I am talking about. Let’s find it out.

Check out other alternative food ideas.

Which types of grass can replace hay for guinea pigs?

Here are the quality and types of grass that guinea pigs can eat instead of or in addition to hay.

Timothy grass

You need to feed your guinea pig’s timothy hay. That’s the best food for them. So, you can do the same with grass. Provide timothy grass instead of hay or any other grass. This grass contains high fiber, protein, vitamins, and minerals and makes your piggies healthy and strong.

Orchard grass

Another type of grass that is also very popular is organic orchard grass. Many guinea pig’s owners feed them orchard hay as the main food, especially if timothy hay causes any allergy. So, you can also choose orchard grass as an alternative to hay.

Dried grass from farmers

If you can’t offer them a hay product designed for guinea pigs, you can contact a nearby farm or farmers for dried grass with minimal dust. This can serve the same purpose as hay.

It also contains abrasive silica for which the piggies can chew on the grass nicely. This will help them prevent the overgrowth of teeth.

Fresh grass without chemically treated

You must provide fresh grass without having any lawn chemicals. Fresh Grass from the lawn, garden or yard with no pesticides or fertilizer can be a good choice. This substance causes severe digestive tract issues and serious complications to health. 

Which types of grass should be avoided for guinea pigs instead of hay?

Guinea pigs can eat alfalfa grass and oat grass, but they should never be used as a substitute for hay. Alfalfa hay or dried grass is only needed in a little amount when piggies are pregnant. It is also required for babies under 6 months. Organic oat grass can be used as a supplement, not as the main diet, or should never replace hay.

The reason is oat grass doesn’t contain all the nutrients or substances that timothy or orchard hay has. So, you can give it as a treat only.

What to do if guinea pigs prefer grass more than hay?

As indoor guinea pigs are herbivorous and love natural foods, many of them will choose grass over hay that’s prepared by the pet stores. When you will provide them two at the same time, they will realize which one is more natural and even healthier for them.

However, as you may not provide grass all the time or it may upset their tummy sometimes, you should try to encourage them to eat more hay than grass. But, how to do that?

First of all, change the brand of the hay, as it’s the main problem of guinea pigs picking grass over hay. Maybe guinea pigs don’t like the product you are feeding them. If it doesn’t work, don’t offer your guinea pig hay and grass at the same time. Make hay available all the time inside their cage. Provide them grass in less amount and not so frequently. Once they are used to hay, withdraw grass completely or offer them occasionally as a treat or supplement.

However, if you can provide them fresh and good quality grass all months, you can feed them regularly in addition to hay and fresh vegetables.

How much grass can guinea pigs eat instead of hay?

If you use grass instead of hay, guinea pigs will need a lot of grass to meet the daily requirement. But, replacing hay from grass may upset their tummy. So, you have to do that slowly. Increase the quantity gradually and you will learn how much grass they can eat without having any health issues. Furthermore, be careful of overeating, as it will cause obesity and other problems.

However, it’s hard to fulfill the need for hay with fresh grass, as they require unlimited amounts of hay. Hay is the dried grass that is more suitable for indoor guinea pigs because they are more used to it.

Tips to feed guinea pig’s grass instead of hay

Here are a few tips that you can follow if you want to feed your guinea pig’s grass instead of hay

1. Offer them fresh grass.

Fresh grass is good and almost similar to hay. It contains vitamin C and high fibers that are mandatory for guinea pigs. It also has abrasive silica just like hay. So, it will prevent their teeth from overgrowing as they chew on them. If you can try to give them dried grass from a farm.

2. Try to provide timothy or orchard grass.

As timothy or orchard grass provides the same nutrients as hay products, and guinea pigs’ bodies are well adapted to them, go to one of those.

3. Grass shouldn’t contain any chemicals.

Lawn chemicals, fertilizers, and pesticides are dangerous for little piggies. So, never give them any grass that’s chemically treated.

4. Give them less dusty grass.

Any kind of dust will affect your guinea pig’s respiratory system and cause allergies. So, make sure the grass is free from dust or less dusty as possible.

5. Grass shouldn’t contain weed or clippings.

Weeds and grass clipping are bad for their health. Ensure it doesn’t have it.

6. Make sure grass isn’t wet.

Wet grass is also unhealthy for their skin and gut health. So, be careful.

7. Check out if you provide them all nutrients.

Guinea pigs can’t manufacture vitamin C in their body. So, you have to make sure you offer them vitamin C rich foods as you aren’t giving them hay. Good quality grass and vegetables can ensure that.

They also have high fibers, other vitamins, and minerals. If you see your guinea pig getting sick because of grass or not getting enough nutrients, consult a vet, change your diet plan, and switch to hay.


Guinea pigs can eat grass instead of hay when it’s not available. You can also provide them grass as a supplementary diet aside from unlimited hay and enough vegetables. However, make sure that grass is fresh and doesn’t contain any chemicals, weeds, or clippings. Also, offer them dried grass instead of wet grass.

FAQ on grass vs hay for guinea pigs

What can you feed your guinea pigs instead of grass?

You should provide your guinea pigs hay instead of grass to keep them healthy, strong, and free from disease. In fact, hay is the main food on their diet chart. If you give them grass as a supplement and now want an alternative to grass, I suggest you focus on offering them unlimited hay, a good amount of fresh leafy vegetables, and pellets.

Can you feed grass pellets instead of hay?

You shouldn’t feed your guinea pig grass pellets instead of hay, because it gets dissolved into a paste in the mouth and can’t control the growth of the teeth by grinding down. Moreover, grass pellets don’t offer the same amount of nutrients as hay and many products aren’t healthy to use in the long run.

Know more about pellets for guinea pigs.

Can guinea pigs eat fresh grass instead of hay?

You can feed your guinea pig fresh grass instead of hay if it’s not chemically treated and doesn’t cause any digestion issues. However, hay works better as the main food for guinea pigs than fresh grass in the long run.

Learn more about fresh grass for your little pigs.

Can guinea pigs eat grass clippings instead of hay?

Guinea pigs can’t have grass clipping instead of hay, as it will cause bloating, diarrhea, and even serious health problems. Grass clipping fermate too fast. Fermented grass clippings or clipping containing bird droppings, dog poop, or pesticides are dangerous for guinea pig’s health. So, you must avoid that.

Can guinea pigs eat grass wet grass instead of hay?

You shouldn’t feed guinea pigs wet grass. Wet grass will cause skin infection if your guinea pig’s skin comes in contact with that. Moreover, eating wet grass may lead to digestion problems like diarrhea or bloating.

Can guinea pigs eat all grass?

Guinea can’t eat any kind of grass. You have to offer them fresh grass without having any pesticides, fertilizers, animals toilet, bird droppings, weeds, and any other lawn chemicals. Moreover, timothy and orchard grass are good for guinea pigs.

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