Windowsill Herbs and Edible Plants That Are Safe to Grow With a Cat

Basil, rosemary, thyme, sage, dill and coriander are listed as non-toxic to cats. Chives, garlic, onion and leek are the ones to worry about because they damage a cat's red blood cells, and lilies damage the kidneys. Keep them out of reach and treat any nibble as a reason to call a vet. Oregano, tarragon, mint, parsley, bay, lavender, lemongrass and chamomile sit in a milder tier, usually causing an upset stomach.

Why it matters more here

A plant that is toxic to a cat in Cornwall is toxic in Caithness. What changes is exposure. Edinburgh has about seven hours of daylight at midwinter against much longer days in summer, which pushes herb-growing indoors for more of the year than in a climate where basil or coriander can sit on a patio from spring to autumn (see the windowsill growing guide). More months with pots on a sill means more months of a curious cat sharing space with them.

Safe: common windowsill herbs

All of these are listed by ASPCA Animal Poison Control as non-toxic to cats. That does not mean a cat should eat handfuls of any plant: gorging on foliage of any kind can still upset its stomach.

Cat grass, usually a tray of young wheat, oat, barley or rye shoots, is sold for cats to chew. If you grow it yourself, skip pesticides and fertiliser on that tray.

Catnip (Nepeta cataria) is a stranger case. ASPCA lists it as toxic to cats, though the effect is mild: many cats love it but it can cause vomiting and diarrhoea, and it makes some cats sedated and others stimulated. Keep an eye on how much a cat gets.

Toxic: windowsill plants to keep away from cats

Lilies belong at the top of this list, though they are flowers rather than herbs. True lilies and daylilies (Lilium and Hemerocallis) are the most dangerous common plant for cats. Cats Protection warns that licking pollen off their fur or drinking from a vase containing lilies is enough for a potentially fatal reaction, so the risk is not limited to eating the leaves. ASPCA lists vomiting, inappetence, lethargy and kidney failure, and death is possible. If a cat has had any contact with a lily, treat it as an emergency and contact a vet straight away rather than waiting for symptoms.

The alliums are the ones to worry about. Chives are a compact, easy indoor pot herb, and garlic, onion and leek are the kind of thing a keen cook keeps within reach of the hob, which usually means within jumping reach of a cat. ASPCA and the RSPCA both describe damage to a cat's red blood cells causing anaemia, and the RSPCA says this holds even when cooked. The RSPCA lists pale gums and a fast heart and breathing rate as signs, though they may not show for days. This is not in the tier of a mild tummy upset: it is potentially life-threatening, and neither source gives a safe minimum amount.

Lemongrass, oregano, tarragon, mint, parsley, bay laurel, lavender and chamomile are a lower tier. ASPCA lists gastrointestinal upset, vomiting or diarrhoea, and in parsley's case a sunburn-like skin reaction, generally after a larger amount, not blood or organ damage. Chamomile can also cause allergic reactions and, with long-term use, bleeding tendencies. Bay laurel carries one extra risk: a cat that swallows whole leaves can get a blockage. Parsley is easy to assume is safe alongside basil and coriander; it is not. Keep these out of reach, but a single curious bite is a watch-and-see, not an emergency.

What to do about it

If chives, garlic, onion or leek are already growing on the sill, the simplest fix is height and separation: a shelf or hook out of jumping range, not the surface the cat already treats as territory. For the mild-tier plants, out of reach is still the right default.

If a cat has definitely eaten chives, garlic, onion or leek, do not wait for symptoms. Contact your vet, or an emergency vet out of hours, straight away, since the red blood cell damage may not show immediately. The Animal PoisonLine (01202 509 000) is the UK owner-facing 24-hour poisoning triage line run by the Veterinary Poisons Information Service, and it charges a fee, so check the current cost. Note roughly how much was eaten and when, and take the plant, or what is left of it, with you.

Common questions

Sources