Passiflora Caerulea

Short version:

I chose this passion flower because it was frost hardy perennial climber that grew in some shade, was evergreen and provided edible fruit. It has done brilliantly in my garden and has amazing flowers followed by orange, egg shaped fruit. 

Passiflora / passion flowers are gorgeous as both a plant and a flower. The whole structure with its many dangling vines can transform a bare surface, whilst the individual flowers look incredibly exotic. There are many passion flowers of varying colours – but you may have noticed, I’m only interested if a plant is edible. I’m therefore, only talking about passiflora caerulea because it ticks all of my boxes.


I really think they are stunning. It has a long flowering season. It can begin flowering (here in London) in late May and can continue till September. This will depend on the weather from year to year. The bees love them, and I often see them buzzing around the vines. This is of course also important for pollination so that the flowers will set fruit.


Of course, it would be wonderful to grow passiflora edulis as these are the passion fruit that we recognise from the shops. Unfortunately, these wouldn’t survive the winter outdoors (I have neither the space nor the patience for greenhouse growing) and it certainly wouldn’t be warm enough in the UK alfresco for the fruits to fully develop. The caerulea is a decent substitution. The fruits are a gorgeous orange colour with a size and shape similar to a hen’s egg. These are edible – WHEN RIPE. When not ripe enough the fruit can cause tummy troubles. The fruit does need a good summer to ripen. A word of warning though – only the pulpy seeds are edible. The rest of the fruit should be discarded and the rest if the plant is also toxic. If this sounds worrying then to put your mind at ease – or maybe give food for thought – potato leaves are also toxic. Potatoes, along with tomatoes and aubergines are part of the nightshade family and none of the leaves of those plants should be eaten either. With any unusual edibles it’s a good idea to do your own research and read websites that you trust for information. I think that the Royal Horticultural Society is a good resource.

Taste is also important. I won’t lie. They don’t taste much like the passion fruit we’re used to – but it tastes OK. Nothing amazing, but pleasant enough.

Vertical gardening

It uses tendrils to climb up anything that will support it. In my garden it climbs the blackberries and the grape vine. It’s woven itself though the blackberry bushes and has resurfaced again about 4m away from the original plant. 

The tendrils are great because this is not a plant that will damage brickwork, unlike ivy – which tunnels roots into mortar and is impossible to remove. I did mistakenly allow ivy to climb up a house once because I thought it was beautiful. When we came to move, I spent about 10 hours trying to remove the ivy. I yanked, scraped, scrubbed and brushed, but you could still see the debris of tiny roots entrenched in all available pores.

The climbing also means that it takes up a small footprint, which is a bonus for small gardens. You could have it scramble over a bike shed or to add colour and interest to a fence or wall.

Hardy perennial in British weather

The different varieties of passiflora vary in how hardy they are. Caerulea will survive outdoors fine and ours didn’t seem to be bothered by frost. In our garden in London it can be evergreen. It is deciduous to evergreen depending on how warm the local area is. Being evergreen means that it has made a great living screen by our fence. It has hopefully given our neighbours some protection from my child’s mooning (yes, that’s not a typo – but she is only 3 – and getting naked on private property seems to be her thing) and screaming (something else I think is also connected to being 3).  

It also seems to do fine in shade. Its roots and the first 4 feet of the plant spends most of the time in shade. If you’re looking for edible fruit though, you’ll want it to grow in decent amounts of sun.

It returns year after year, despite freezing conditions. It does follow the adage: first year sleep, second year creep, third year leap – or it did for me anyway. First year it was a sorry looking thing with a few scraggly vines. The second year it provided a bit of privacy and one orange fruit.

This being the third year it covers a good 2 square metres or so. It has wonderfully flexible vines so I could weave it in and out of the frame however I liked. It also has about 20 or so fruit which are now all turning orange. With our current blackberry canes going mental and a grape vine in the middle, it is a little difficult to see where one plant ends and the other begins.

Doesn’t need looking after

In South Africa it counts as an invasive species that takes over indigenous plant life. I haven’t read anything that makes this plant a cause for concern in the UK. It doesn’t propagate particularly easily here, and I have never seen it anywhere in the wild. This does mean that it grows brilliantly, even with plenty of neglect. I’ve read that it in fact does best when allowed to get a little unruly and not kept too neat. They do grow to be quite large plants, though some patience is required in early years. When the plant is in its first couple of years and doesn’t look like much, don’t be tempted to fill in the space (like I did – doh!) with other perennials. If you want something vertical you could grow some peas, beans or maybe a cucamelon or another annual to fill in the gaps because this passiflora really will fill out.

This is an arch in Vézénobres in France. In July the fruit was already ripe and it looked stunning. It seemed quite a popular plant in the local area.

It’s vigorous enough to cover a surface – but not so overly aggressive, like ivy, that you’ll continuously need to hack half of it down just to keep it in check. It’s easy enough to remove whole vines if you do need to keep it small. Pinching out the growing tips of the vines can help it to branch more.  

If you’re looking to grow something that tastes amazing, I’m afraid this probably isn’t it. I’ve decided that there are still plenty of other reasons to grow these and I’ll continue to do so until I decide I need the real estate for something else. That something else is going to have to have all the bonuses of climbing, being hardy, being evergreen, be able to thrive on neglect, be bee friendly, be beautiful and then taste pretty wicked in order to trump passiflora caerulea.


Short version:

The husband proved me wrong, but I couldn’t be more pleased. Thornless blackberries are a good shade tolerant, easy to grow, easily propagated, prolific berry that can be trained to grow vertically to reach the sun better or provide an evergreen screen, taking up a small footprint.

In 2007 we moved into a one bed house. Yes, actual house with kitchen/living room on the ground floor and a spiral staircase in the corner. The garden was about 3x3m and very shaded. Despite being in the shadow of the house most of the day, we were glad to have a garden at all in London. One day the husband returned home (having gone out for paint and sandpaper) and presented me with a thornless blackberry cane. I was rather disparaging and completely ungrateful. We were fairly broke having just moved in. We were 15 mins walk from the edge of Wandsworth common. Why on earth would we pay £10 to buy a blackberry and then give it real estate in our tiny inhospitable garden?

He’d paid for it already, so I planted it next to the fence in a corner. It was of course in the shade. In the first year it did very little and we maybe had 5 or 6 blackberries. In the second year it did a bit more and we had a bowlful of blackberries. In the third year it had a large number of canes that went up over the fence into the sun and we suddenly had an explosion of fruit. We had so many we didn’t actually know what to do with them. We mostly just ate them off the bush. They were the most delicious and chubby blackberries we’d had. This completely followed the adage first year sleep, second year creep, third year leap! The second year there was lots of green but not much in the way of berries.

So here’s some helpful terminology:

PRIMOCANE – a cane that is a year old, when it has lots of leafy growth.

FLORICANE – a cane that is 2 years old and will now fruit.

So that explains why the first year there was so little fruit because of the single cane that was already in existence. The young root system would only support growth of a small primocane or two. The second year there would have been fruit on those small 2 year old canes (now called floricanes) and there would be plenty of growth of new primocanes. In the third year there would have been plenty of floricanes to provide lots of blackberries. Also, the long canes were now reaching over the fence and making it into the sun.

When we moved I couldn’t bear to leave this amazing plant behind so I took cuttings, stuck them in soil and hoped they’d root. Only 1 did due to my lack of knowledge, lack of time and the stress of moving. It then lived in a pot on a shaded balcony for 4 years as the new place had no bare soil. I think we had about 10 blackberries in those 4 years. It moved with us to our current house and this is what we have just 2 years later:

Blackberry Hedge

I knew that it was evergreen, was fine with shade and was still lovely and thornless. We have a short fence which I’m grateful to my neighbour for as it allows our garden more sun. We get on really well with the neighbours and in order to keep it that way I’ve made our blackberries into a living screen that gives them some protection from the bare bottom of our child (why do toddlers like being naked so much?), her tantrums and the general cacophony of our household.

I started this hedge by putting this green wire frame up all round 2 sides of the garden to support vertical growing.

I only started with the one blackberry plant (unfortunately I don’t know the variety) so I bought another variety of thornless blackberry (Oregon thornless). The first year, being the incredibly impatient person that I am, I propagated with some serpentine layering. The next year I had 5 blackberry plants. I wove the newly grown 10 ft long green canes in and out of the wire frame. Over winter they lost a few leaves but mostly remained intact and a couple went a lovely red. This year we have a what looks to be a bumper crop.

Reasons to Grow Thornless Blackberries

So… despite my initial reaction at being bought a thornless blackberry I would whole heartedly recommend them because:

  • They use a small footprint if you train it up, which only requires tying it up a couple of times in the summer when it’s turning into a triffid.
  • They make a great living screen all year round if your winter isn’t too harsh.
  • They do fine in the shade. The berries are bigger and sweeter if they can reach some sun though.
  • Despite the ease of blackberry foraging, often when picking blackberries you have to pick at height to ensure no animals have weed on them (including the drunken animals who couldn’t wait till they got home!) Also, I’ve found that sometimes even the yummiest looking wild blackberries can taste very tart or bland. You must find a good patch and hope that some other forager who knows about it hasn’t beaten you to it.
  • The thornless-ness makes them a pleasure to pick and train. This is not something you can often grow from seed. Even if you take a berry from a thornless bush it may have be pollinated by a prickly variety as there are brambles hiding in the corners of most gardens I’ve seen.
  • They do fine with a large amount of neglect and don’t need special conditions like the ericaceous soil (acidic conditions) required for blueberries and raspberries.
  • Out of the fruits I’ve grown, blackberries provide the largest crop in the shortest time from propagation.


They are easily propagated.

I would however not recommend going crazy with the propagation. I think I’m going to have to dig a plant or two up as they are really prolific. If you can find someone who blackberries already, I’m almost certain they wouldn’t mind you having a cutting. After the second year they won’t be short of canes. You can then also check that they’re tasty before growing it.

Mid to late summer is usually best for propagating. 

Tip layering

This is the easiest way. In fact, if you don’t keep the canes off the ground they can naturally root where tips touch the soil. 

  1. Find a healthy primocane.
  2. Where the tip easily touches the ground, dig a hole (either straight into the ground or in a large pot) and bury the tip about 10cm deep.
  3. Keep it watered (a larger pot is easier to keep moist).
  4. In about 2-3 months (depending on conditions) roots should have grown (just dig up where the cane goes into the ground to see) and you can sever the new plant from the old cane which will still go on to grow blackberries on it.

Serpentine layering

This isn’t quite as easy as tip layering, but it is useful for propagating lots of plants in one go. 

5. In about 2-3 months (depending on conditions) roots should have grown and you can sever the connections between the new plants. It would be advisable to move them further away from the parent plant. 


The reason my first attempt at cuttinsg weren’t hugely successful is because I literally cut off stems and stuck them in soil.

  1. Choose a healthy primocane. Summer is best but cuttings taken the rest of the time may just be less successful. Cut the top few inches using a clean knife or secateurs. I haven’t a magic number of inches but somewhere between 4-8 would probably do it. Cut it about 2cm below a leaf bud. This will be where the roots will grow from.
  2. You can also take a cane and cut it into sections. Each section could grow you a new plant.
  3. Remove most of the leaves of each cutting. Leave the leaf buds.
  4. Stick into any type of damp compost. There are arguments for using soil less growth medium thingys as there will be less chance of it going mouldy – but honestly I don’t have the all the fancy bits and bobs professionals do and I certainly don’t have the space to store all of it. You can dip it into rooting hormone if you like but I’ve found that blackberries do fine without.
  5. Leave in a shady spot for a few months. 
  6. It’s ready to plant out once roots have grown.

Cuttings tend to be less successful than layering as the cutting does not have any nutritional support from the parent plant.


After the canes have fruited and been harvested the floricanes should be cut down at the base of the plant and removed to make space for the primocanes to fruit the following year.

You may spot the very large design flaw to this blackberry hedge. All the growth was woven into the frame when they were the primocanes last year. They’re now fruiting and will need pruning in the autumn. When I do that the whole wire support will be bare. In addition, because I’ve woven the canes through this wire support to make this blackberry hedge, they’re going to a huge pain in the seating area to remove. The wire support is currently too full to take this year’s primocanes. This year’s primocanes are therefore just kinda blowing in the breeze above the lawn, trying their hardest to make it to the ground.

In fact, the whole thing collapsed in this very windy and rainy summer.

The plants are far too close and there is no way our family needs 5 blackberry bushes.

My new plan is to wait till after all the berries have been harvested and prune all the floricanes. Once that’s done there should be nothing to attach the plants to this fence. I’ll then dig up 2 plants and plant them across the lawn and provide a strong vertical support. Hopefully then I can tie the canes from the opposite plants together to make an arch that goes across the narrowest bit of the lawn. Each new year the new primocanes can be tied together. Then every year the tied together canes should be the same age and can bear fruit together and be pruned together. With the plants that haven’t moved, half of the primocanes will go back into the hedge, then there should always be space to add primocanes where floricanes have been removed. The hedge shouldn’t get too heavy and it shouldn’t fall again.

Well, there are all my mistakes (so far). I’m afraid I didn’t know enough about primocanes or floricanes but, hopefully, dear reader you know all about then now. Of course, learning is all part of the fun and I don’t mind rejigging the garden. The damage to the roots might put me back a year, but then after that, hopefully there’s going to be some good structure that we can enjoy for years to come.

One last odd thing – apparently you can eat the shoots and young leaves as a spring veg. I tried this and I didn’t like it. They didn’t taste amazing and were very astringent. I may have been doing it wrong and may not have eaten them early enough. If I do discover the secret to making them tasty I shall let you know!

I hope you give these a go and if anyone can identify my blackberry then I’d be interested to know. I’m afraid 2007 ignorant me didn’t even consider varieties back then. I can imagine in 2030 I’ll be sitting there thinking how naïve I was back in 2019!

Or… feel free to suggest any varieties in the comments.