Passionfruit vines and frost

Bit of a novice gardener here - I planted a passionfruit last October and it has been growing awesomely. I haven’t looked at it for a week or two but looked yesterday and a lot of the ends - so the latest growth - is all shriveled up and dying. I live in the Waikato and we have had some cold weather with frosts the last couple of weeks. Would the frosts have affected it? Can I do anything to help it and should I cover with a frost cloth?

yes. Don't worry about it. Come spring cut it back a bit, fruit grows on new growth, so you want to keep it within limits (It can grow for miles), and that will take care of any frosted bits you get now.

still protect it with frost cloth then wont get any worse

I cover mine with frost cloth [ good quality not that thin stuff from the red barn] and do not prune until spring so that the extra long tendrils are protecting the main vine.
Its now about year 6 alive [in waikato] and produces many kg of fruit

Thats about as long as they last isn't it? Then you put in a new one

Yip. I reckon 8 yrs tops - and those last 2 years it looks manky and doesn't produce a lot (but then I don't feed or even water them much). That's my experience here anyway. Luckily I've always got them self seeding and often one or two pop up in situ right beside the current vine so by the time the big vine is 5 or 6 I've got one or two 1 yr olds under it.

I have grown passionfruit in the Waikato for many years. The only parts you need to cover to protect from frost is the main stem. The rest of the plant usually dies right back naturally anyway, unless it is grown under a covered pergola or similar. For ongoing good results you should raise a replacement every 3 or 4 years as they slow down and wear themselves out. Need lots of water when fruit are maturing to prevent shrivelled fruit and poor amount of contents.

I have a passionfruit in a large pot, the leaves are turning yellow. My question is what is wrong with it and can it be saved

Passionfruit plants are the most fickle plant I have ever tried to grow. No good in most places in the South Island because of the cold winters which they hate.
Don't grow them in pots as they like to find their own feet. Feed them like lemons, they require lots of food and regular watering. They may last up to 4-6 years, and then suddenly die.

Sometimes - depending on when/how they were potted, they can really hate being transplanted, and never do well from then on. But if potted for later planting out or moved to their final home before they get to a good size (a few inches tall) they are usually ok. Any bigger and you disturb their roots - and they HATE their roots being mucked with.

Planting out from a pot is a different story because you can usually transplant from a pot without mucking with the roots - if reasonable care is taken. I have the most success with the self sown seedlings that I just leave where they pop up.

They're one of those plants that love water but hate their roots being wet for any period of time so good drainage is a must.

They love toasty warm roots, I find they do well if the soil is covered with stones/rocks because the rocks hold the days heat and re-radiate it a bit at night. Even better if planted beside a nice warm stone, brick or concrete path.

I have one on a trellis facing south, and it is exposed to some cold-arse southerly winds occasionally. But it is in ground covered in rocks and next to a concrete path. It gets a little frazzled after a few cold southerlies but it always bounces back and is happy come late spring. It grows through the trellis and gets quite a bit of north-westerly sun in spring/summer.

We only get about 2 or 3 near frosts every winter though, no good solid frosts.