Julz, If you're new to gardening, nasturtiums are easy to grow from seed. My guinea pigs used to eat its leaves and flowers. There's nothing cuter than a guinea pig eating flowers! Apparently, other guinea pigs don't like the leaves so much.
Other recommendations, if you don't mind.
Dandelion leaves can be high in oxalic acid and vitamin C, but you asked about flowers which as Lynlee said, should be fine.
I have a lot of chickweed in my so called garden, and they're yummy stuff.
If you're putting in fruit trees, cherry guava is excellent. Brisbane climate is perfect for it. It grows lushly without help and the fruits are ~*! (amazing beyond words), if a bit too sugary for guinea pigs. It doesn't grow too tall either so it's easy to pick. It also comes as pineapple guava.
Rocket and basil are also easy to grow, but rocket is very high in calcium (good for humans though).
I used to feed my piggies bokchoi, but they really don't like the stems. Bokchoi and many asian leafy greens are in the Brassica family the same as cabbages, and cabbages can cause bloat, so I am a bit wary of feeding too much.
Aloe vera is also good to grow. Fast growing, easy to contain, will grow in shade/semi shade without you giving it any attention. Useful for soothing guinea pig skin. I bought a tiny plant a long time ago, and in two years it FILLED two large rectangular self-watering pots. I haven't touched it for four years and it looks magnificent.
Mints and chamomile are also supposedly easy to grow, but I've never been much good at them. They're good for a bit of variety in their diet.
Worm farm! With all that guinea pig poo, it's a must. (Guinea pig poo must not have Revolution etc in them, unless you leave it a few months before giving it to the worms.)
Paw paw leaves I think have sap in them, and I would stay away from anything with sap in it, but dandelion has sap too... Still, paw paw leaves seem a bit iffy.
Oh, might I add, asparagus is such a good idea. A hedge of it is so pretty and it'll give you spears for years.
I have just started growing nastrurnums in my gardens everywhere so they should be popping up in no time, I know they are good for guinea pigs, 90% of my garden is devoted too my guinea pigs, I do a lot of research but on some things I need a 'helping hand'
I have 4 plants of dandilions and they are very much loving my soil and compost so that is great.
I havent got any paw paw and I dont really intend too get any because I have found they are a bit harder too control and with my limited mobility I dont think I would be able too 'maintain' the trees too their requirements so i have decided too not go with any of those.
I have chamomile in my garden but my boys do not like this and turn their noses up too it, but as soon as I bring in dill/basil and parsley they are crawling up the cage too get at it and honestly Demetri's face goes from each one and he doesnt know where too go LOL really amusing
I have got a huge bunch of sweet corn and plain corn growing at the moment with lettuce/spinach/strawberrys (pigs are not going too get leaves!!).
I also have pennyroyal as a pest deterant, i also have cucumber beans (which Demetri adores). Plus aswell I have tomatoes growing out of control and the boys strive too get as much tomato as they can with me BUT! I am sensible in noticing how much they eat as I have an eating chart for both animals aswell as a weighing chart!!! so everyone be assured that they are getting plenty of everything they need, Aswell as 'Hay and Grain' At all times!. Tho I still get up through the night too see if they have adequate hay and grain till the morning where I top if up for the day time shift.
Well the boys are in their day time cage while I cleaned out the main cage and I have made my own tunnels which I will upload later today or tomorrow and they are made of a special absorbant towling and batting plus a specific typing of wadding for waterproof tunnels. Tho this is my secret design so I am wondering if i should upload pictures of not LOL
. (Please note, I know I have gone off topic here please dont spank me!) *hides*!
The last thing a part from another 2 raised garden beds is a worm farm adn then use the juice from the worms too reboost the soil up, I really want too get totally independant with my gardening so when it comes too the odd trip too the fruit and veg market it will only be a few dollars that I will have too spend at any time throughout the year. Plus there is always heaps of grass (as April can atest too!) I still remember your reaction when you looked out my back door and saw the lush green grass
So in summing up, I am a responsible caring loving devoted piggie owner who cares about all aspects of her guinea pigs needs!.