What Do Guinea Pigs Eat? The Ultimate Veggie & Diet Guide

The first week I had Popcorn and Peanut, I filled their bowl with pellets, dropped in a hay cube, and figured I was done. The next morning, Popcorn stood on her hind legs at the front of the cage, nose up, and let out a wheek so loud my neighbor texted me to ask if everything was okay. She wasn’t hungry. She wanted vegetables — and I didn’t know guinea pigs needed fresh food every single day.

I know better now. The foundation is Timothy hay (80% of their diet), but they also need fresh vegetables daily and vitamin C supplementation — guinea pigs are one of the few mammals that can’t produce their own vitamin C.

TL;DR: 80% Timothy hay, 1/8 cup Vitamin C pellets, 1 cup fresh veggies daily. Best daily veg: bell peppers (high C), romaine, cilantro, cucumber. Feed sparingly: broccoli, spinach, kale. Never: iceberg lettuce, potatoes, rhubarb, chocolate, avocado, meat/dairy. Guinea pigs can’t make their own Vitamin C.

Here’s what a daily diet actually looks like when you get it right:

The Daily Foundation: Hay and Pellets

Before we get to fresh veggies, here’s the foundation of any guinea pig diet:

• Unlimited Timothy Hay: Your piggy should have access to fresh Timothy hay 24/7. Hay provides the crude fiber (20%+) needed to keep their constantly growing teeth filed down and their digestive system moving. Never use alfalfa hay for adult guinea pigs — it’s too high in calcium and protein and can cause bladder stones.
• Vitamin C Fortified Pellets: Feed 1/8 cup per pig per day. Look for plain, uniform pellets without colorful pieces, seeds, or dried fruit. The colorful mixes are unhealthy and encourage selective feeding.

Celery: Crunchy but Tricky

Yes, but with a major warning. Celery is safe and crunchy, which is great for their teeth. However, the stringy fibers in celery stalks can pose a severe choking hazard.

• How to serve: Always chop celery into very small, bite-sized pieces (about half an inch) to break those long strings before feeding it to your piggy. Many owners peel the strings off entirely for extra safety.

Carrots and Cucumbers

• Carrots: Yes, they love them! But carrots are surprisingly high in sugar and Vitamin A. They should be treated as a snack, given only 2-3 times a week, rather than a daily staple. A single thin carrot slice per pig is plenty. Don’t forget, carrot tops (the green leafy part) are also safe and actually healthier than the root itself!
• Cucumbers: Yes! Cucumbers are fantastic for hydration, especially during the summer. However, because they’re mostly water and have low nutritional value, feeding too much can cause soft stools. Two or three small cubes per pig is ideal.

Broccoli and Spinach: Feed with Caution

Not all greens are created equal. You need to be careful with these two:

• Can guinea pigs eat broccoli? Yes, but broccoli is a “gassy” vegetable. Guinea pigs can’t pass gas easily, and too much broccoli can cause painful bloating. Offer small florets only once a week.
• Can guinea pigs eat spinach? Yes, but sparingly. Spinach is high in Vitamin C, which is great, but it’s also high in calcium and oxalates. Too much calcium in a guinea pig’s diet can lead to bladder stones. Serve baby spinach only once every two weeks as a rotational green.

Daily Veggie Rotation: A Sample Plan

A healthy weekly rotation to keep your piggy excited and well-nourished:

Day	Morning Veggies	Evening Veggies
Mon	Romaine lettuce (2 leaves)	Bell pepper (2 slices)
Tue	Cucumber (3 small cubes)	Cilantro (small bunch)
Wed	Romaine + carrot (1 thin slice)	Bell pepper
Thu	Zucchini (2 small pieces)	Cilantro
Fri	Romaine + tiny broccoli floret	Bell pepper
Sat	Cucumber + carrot top	Cilantro
Sun	Romaine + treat fruit piece	Bell pepper

What you should never feed

Just as important as knowing what to feed is knowing what to avoid:

• Iceberg lettuce: Contains lactucarium, which can be toxic, and has almost no nutritional value.
• Potatoes and potato peels: High in starch and contain solanine, which is toxic to guinea pigs.
• Rhubarb: Highly toxic — can cause kidney failure.
• Chocolate, candy, or any processed human food: These are toxic and can cause serious health issues.
• Meat, dairy, or eggs: Guinea pigs are strict herbivores and can’t digest animal protein.
• Avocado: Contains persin, which causes respiratory distress and heart failure.

Buying Timothy hay in bulk online is fresher and significantly cheaper than the small bags at pet stores. Your piggies will notice the difference. For more on guinea pig care, check out our cage setup guide and sounds & behavior guide.