I have a delightful neighbour but ......

A water pistol is a good deterrent.

HurdyGurdy. I’m going to order these thank you.

I've received the "Garden Bargains" catalogue today and there's a product in there called "Scardy Cat Plant" (Coleus Canina) and it says

"This unusual plant will help deter cats and other unwanted pests from entering and fouling your garden. Coleus Canina works by emitting an odour that cats in particular find incredibly offensive and therefore disappear back out of your garden or over the fence". Grows to 45cm.

12 jumbo plugs are £14.99

You clearly need to keep them out of your green house , is there a deterrent you can put down that cats don't like & keep them away without upsetting anyone . I've heard about putting concentrated jeyes disinfectant around an area that you don't want dogs to encroach, maybe it will work for cats too , either way , don't you think your health comes before cats. If your neighbour doesn't care about your health situation, then I doubt she's as friendly or as nice as you'd hope . Now's the time to find out . Surely you wouldn't prefer a fatal asthma attack.

I think you need to buy a water pistol and use it whoever you see a cat at all. Let them find another garden.

Defender Jet spray Pond and Garden protector (other brands are available) worked very well. It shoots a jet of water at the offending animal. These devices are solar powered and cats learn very quickly to avoid. The sonic noise devices impact on children teenagers, young adults and dogs as their hearing is more sensitive. Hope it helps.

We have a lightweight folding trellis which my husband opened to the width of the greenhouse door. He attached some shading mesh to it to block the diamond shaped holes. We use wire to hook it up to the door frame.
In the house, I’d have a spray bottle of water handy. They’ll soon get the message.

Lots of helpful answers thank you. I have taken all the suggestions on board and will be making sure that the cats do not move in permanently. It is certainly true that cats choose their owners and recognise when someone is allergic ad that person seems to become a magnet.

Spray them with water they will eventually get the message.

We are the only cat free garden in our road, and we have nesting birds. I have the neighbours’ permission to spray their two new large kittens with water. I am out there in a flash! Our cat died some years ago, and was a hopeless hunter, but two of the local tortoiseshells can go from standing to 6foot in a second. I include them in my attempt at deterrence.

I get what others are saying about your neighbour not being able to control their cats' wanderings, but maybe have a word anyway and warn her they may come home in a huff some days and wet - I would advise keeping a water spray bottle to hand until the cats get the message that your house is not an extension of their own, and, yes, some kind of wire door for your greenhouse, I think they see them as cat saunas! I know ours do.

Wow - is there REALLY such a 'thing' as Lion Poo? Is it the actual stuff?

I live within a stone's throw of a Safari Park - I wonder how amenable they might be to selling some to visitors .

loaded water pistols at the ready

Why do cat owners think cats can't be trained? I have had cats in past years and they were trained to stay in my garden. I discouraged them when trying to climb fences to get out. One was allowed out in the morning to escort children a certain distance to school and the same when school was out. She would sit at same spot waiting to escort them back to the house. I have DiL who argues that cats can't be trained yet when she takes the dog out for a short walk she calls the cat who then follows them around about and back. Is that not training? Wire door, loads of cayenne,/paprika pepper round about your greenhouse may break their habit.

I sympathise as we have 4 cats who like to be friendly to our neighbour (a miserable old woman!).
She is always complaining about them catching the birds in her garden (she puts bird food on her lawn so of course they do!)
We bought her a couple of hanging feeders so she can feed the birds safely up high as we do but she still puts food on the lawn.
Our cats have bells on collars so we can really do no more.
I hate them catching birds too but it is nature.

Sorry to hear of your dilemma ! Must be difficult ....I love cats, personally, but suggest you could phone a Vet or the Cats Protection people, RSPCA or Battersea cat and dog rescue ...or even a local cat rescue if you have one .....and also speak to your Asthma consultant and asthma groups ....it wouldn't seem fair to have to wear a mask all the time, but I did once read there are nasal sprays you could try ...nuisance, but if it stops you have a bad attack, may be worth it ! There are also certain things cats HATE the smell of ...not sure what they are (ha ha ...different subject but we had mice in our shed, and someone suggested Eucalyptus oil ....it worked !) so there may be a natural remedy you could try ! On the other hand (tongue on cheek !) as someone who has had many cats ...try encouraging them ....a cat being a cat may soon leave as they generally do the opposite of what you want them to ! good luck

I swear cats know when you are allergic to them. I am allergic too and I always acquire a cat wherever I move to. Also if I visit friends with cats, I take an antihistamine and if I don't touch the cats and it's for a brief period, I am generally fine BUT yes, you've guessed it, they always come and sit on my lap or shoulder or I get bookended in with one either side

First, do speak to your neighbour. If she is a responsible cat owner, she will understand that this is a serious health issue and try to help you keep her cats out of your garden.

If I were your neigbour, I would suggest you flung a bucket of water over my cat, or sprayed it with a water pistol, until it or they took the hint. I would also feel obliged to put up a fence that the cats could not climb, but legally you cannot demand that she does so.

It is certainly harder to control cats than dogs, but it can be done.

Keep your greenhouse door closed and open roof vents to air it and keep it cool.

Open your house windows on a small latch, or install fly nets.

If a cat walks in, shoo it out. I realise that if it has shed fur you will still be troubled by the fact that it came in, but you need to make it clear to the beasties that you don't want them in your house.

Most cats dislike the smell of ordinary household vinegar, so in warm weather when you have doors and windows open, try placing a small bowl of vinegar on the sills.

Hissing like an angry cat usually deters them too. A recording of a dog barking, or a goose or gander hissing might work as a deterrent too.

hasnt your green house got a door? if not put some netting across the opening..... or spray the cats with water ..

Oh kwest, your post made me so angry. I think I’d have gathered up those poor dead ducklings and put them on the vicar’s doorstep.
After that, every time those cats appeared in my garden they’d be blasted with the hose set to jet!

Here's a suggestion about your greenhouse door. I have a holiday home in a very hot country where without mesh at each door I would be inundated with mosquitos and also encourage the odd snake. Unfortunately, such mesh is no deterrent for cats that have already decided it would be nice to get inside - they simply stretch up and pull on the mesh with their claws creating a hole - so I would suggest a much bigger mesh - maybe something like chicken wire, and certainly wire rather than nylon. I guess you do actually want bees to get into the greenhouse anyway so a door which allows that seems to be important.

I'm just allergic to the sight of a cat in my garden. My birds are more precious than somebody's cat. Sorry cat lovers out there.

Your neighbour won’t be able to stop her cats coming into your garden unless she makes them house cats which most cat owners won’t do especially if their cats are used to roaming free. It’s your responsibility to make your greenhouse inhospitable or inaccessible. We made a removable mesh door to stop our own cats getting into our greenhouse. Works a treat and inexpensive.

Try this from amazon. We have it at the back patio door to keep the flying monsters out over the summer. It's attached by sticky backed velcro and the magnets makes sure it closes whenever you go in or out. Everything is in the packet to enable you to fix it up and it's really easy. I can't recommend it enough.

We had a duck and 10 ducklings in our garden three days ago.
In the morning we woke up to 9 massacred ducklings with just the duck and one duckling alive. The next day there are none.
One year we had two ducks and their brood that settled late afternoon in the middle of the lawn. I phoned my neighbour, the vicar's wife, and asked if she would keep her cat indoors that night so that the ducks might survive until morning when they could walk down to the river. She refused. Next morning at 5am we heard a cacophony of ducks terribly distressed in the garden. The next door cat was there as was another from a few doors down and every duckling had been killed.