Best Microgreens for Guinea Pigs

Guinea pigs are herbivores. Their diet is built on hay, a fortified pellet and a limited amount of fresh vegetables — and microgreens can become an unexpected favourite within that last category.

Hay and a guinea-pig-specific pellet form the base. Fresh leafy vegetables sit on top of that in limited amounts — the MSD Veterinary Manual’s chapter on Nutrition in Rodents and Lagomorphs describes rodents and lagomorphs as maintained on pellets, hay and “a limited amount of assorted vegetables”. Microgreens such as lettuce, broccoli, kale, cilantro and cauliflower are a sensible way to fill part of that vegetable allowance.

Guinea pigs cannot synthesise their own vitamin C. The MSD Veterinary Manual states that “guinea pigs and capybaras cannot produce their own vitamin C, so they should be offered commercial guinea pig pellets (fortified with vitamin C)”, and its chapter on Nutritional Problems of Guinea Pigs puts a number on the requirement: “guinea pigs need at least 10 milligrams (mg) of vitamin C per kilogram (kg) of body weight per day (pregnant females need 30 mg per kg per day)”. Deficiency is scurvy, and the Manual lists loss of appetite, dental problems, swollen joints, bleeding under the skin or in organs, weakness and possible death among its consequences.

Microgreens do contain vitamin C, and in measurable quantity: Xiao, Lester, Luo and Wang (2012) assayed 25 commercial microgreens and found total ascorbic acid from 20.4 to 147.0 mg per 100 g fresh weight, alongside carotenoids, phylloquinone and tocopherols, and reported the cotyledon leaves to have higher nutritional densities than mature leaves in the USDA database. That is the study behind the general claim that microgreens are more nutrient-dense than their grown counterparts.

But do not treat greens as your vitamin C strategy. The fortified pellet is the reliable source. The Manual’s guidance on a Diet for a Guinea Pig states that pellets “can lose a substantial amount in just a few months, so it’s best to buy fresh pellets regularly and supplement them with vitamin C–rich fresh vegetables and fruits”. Pellet freshness therefore matters at least as much as which microgreen you picked. The same page names good-quality grass hay such as timothy or orchard grass as “the main food in your guinea pig’s diet”.

The following are horticultural characteristics — how hard each variety is to grow and how long it takes. They are not feeding recommendations, and there is deliberately no frequency column.

Microgreen	Growing Difficulty	Presoak Seeds?	Preferred Growing Medium	Harvest Time
Basil	Difficult	No	Hydroponics	12-16 days
Beet	Easy	Yes	Soil	10-12 days
Broccoli	Easy	No	Hydroponics	7-14 days
Carrot	Intermediate	No	Soil	14-28 days
Cilantro	Difficult	No	Soil	21-28 days
Collard Greens	Easy	No	Hydroponics	10-12 days
Dandelion Greens	Easy	No	Soil	12-25 days
Endive	Intermediate	No	Soil	8-15 days
Kale	Easy	Yes	Soil or Hydroponics	8-12 days
Parsley	Intermediate	Yes	Soil	21-30 days
Radish	Easy	No	Soil or Hydroponics	6-12 days
Watercress	Difficult	No	Hydroponics	8-12 days

This is the caution with a source behind it. The MSD Veterinary Manual states that “feeding a large amount of alfalfa and pellets containing high levels of calcium is not advised, because it can lead to urolithiasis in some rodent and lagomorph species”, and notes that high amounts of alfalfa caused urinary problems in pet rabbits and guinea pigs. Urinary stones are a real, diet-linked problem in guinea pigs, and mineral load is the documented lever.

An earlier version of this page named five varieties — kale, broccoli, red cabbage, amaranth and sunflower — as the calcium-rich ones to ration. We have removed that list, because we could not find a measurement to stand it up. Calcium in microgreens has been measured: Xiao and colleagues (2016) reported the mineral composition and content of 30 Brassicaceae microgreen varieties, which is the family kale, broccoli and red cabbage belong to. Amaranth and sunflower are not Brassicaceae and were not in that study, and we know of no published comparison of calcium across all five. So we are not going to rank them.

What the sourced evidence does support is the general caution above: mineral load is the documented lever on urolithiasis, calcium content differs from one variety to the next, and because microgreens concentrate nutrients relative to the mature plant, “a small amount” is the right instinct with all of them — particularly for an animal with any history of urinary problems. Which varieties to limit, and by how much, is a question for your vet, who can weigh it against the rest of the diet.

Two corrections while we are here, both from an earlier version of this article. Oxalic acid is not a nutrient — it was listed as one of the benefits, when in fact it is the compound behind part of the bladder-stone risk, so it belongs on this caution list. And plants are not a source of vitamin D; guinea pigs get theirs from their pellets, not from greens.

How much in total? We are not going to publish a number. Fresh vegetables are a limited part of the diet, they should be introduced gradually, and the right portion for your animal depends on its weight, age and health. Ask your vet.

This article is general information for guinea pig owners, not veterinary advice. Species-specific diet questions — vitamin C supplementation, portion sizes, and anything to do with urinary problems — belong with your veterinarian.

• Nijboer J, Fens A. Nutrition in Rodents and Lagomorphs. MSD Veterinary Manual, Management and Nutrition. msdvetmanual.com
• Hess L. Nutritional Problems of Guinea Pigs. MSD Veterinary Manual, All Other Pets. msdvetmanual.com
• Hess L. Diet for a Guinea Pig. MSD Veterinary Manual, All Other Pets. msdvetmanual.com
• Xiao Z, Lester GE, Luo Y, Wang Q. Assessment of vitamin and carotenoid concentrations of emerging food products: edible microgreens. Journal of Agricultural and Food Chemistry 2012;60(31):7644–7651. doi:10.1021/jf300459b
• Xiao Z, Codling EE, Luo Y, Nou X, Lester GE, Wang Q. Microgreens of Brassicaceae: Mineral composition and content of 30 varieties. Journal of Food Composition and Analysis 2016;49:87–93. doi:10.1016/j.jfca.2016.04.006
• Our companion guide: Are microgreens safe for pets?

Removed from this list: three vendor blogs. One of them was the origin of the feeding-frequency figures that used to appear in the table above.