How to revive an unhealthy citrus tree | DIY Garden Projects | Gardening Australia

The bat phone rang earlier. It was an emergency call out, so I've brought all of my specialist surgical equipment. Maybe it's a truth extraction, I've come prepared, or a basic amputation. Either way, I'm all set, the doctor is in. Luckily for them, my friends Josie and Xavier have another number to dial for medical emergencies. This call out is strictly horticultural. Josie. Doctor. I assume this is the patient. It is indeed. What's the problem? So Josh, this is our 8-year-old nigami kumquat, and it was actually given to us by my grandmother when we returned back to Perth after living interstate and overseas for a while. And it's actually the first tree that we planted in our garden. So it's quite special to us and it sort of symbolises home. And it's ailing? It is, yeah. It's always been a really healthy tree, but in the last couple of years I would say it's a lot more susceptible to pests. So we've had a bit of scale move in, and it's producing a lot of fruit still, but the fruit seems to drop a bit early and the leaves are falling off as well. When was the last time it was repotted? So it's been in this half-wine barrel now for about six years. Did really well. It's grown to the size you see here, but it's been in there for a while now. Are you feeding and watering it regularly? We do, yep. We try and feed it three times through the year, so sort of spring, summer, autumn, with the compost, and then in between we do a bit of liquid fertiliser. But even though we've been putting that in, the tree doesn't seem to be taking it up anymore. My thinking is it's likely to be either root-bound or the potting mix is just old and stale. Or thirdly, it could be impeded drainage because the drainage holes are now bunged up through swollen wood and also just organic matter. But the only way to find out is to pull it out and have a look. Sounds good, Josh. Let's do it. To begin with, the mulch can come off and be put aside for later. The caster wheels make it an easy job to move the pot into the centre of the deck to give it some room to work, and the tarp will keep the mess contained. Having three people for this is very handy, two to safely turn the pot on its side and one to protect the canopy from accidental damage. The blocks of foam will help to protect the pot, which we're hoping to reuse if it stays together. The underside of the pot looks in pretty good nick, although the drainage holes are a bit clogged up with sludgy organic matter. The only way to find out exactly what's going on is to pull the tree out. It's very compacted, isn't it? It's got a lot of mucky organic matter, probably impeding drainage and not getting enough air to the roots. At first, the root wall isn't budging, but after scraping some of the soil away around the edge of the pot, it eventually wriggles free. So try and pull it out again now? Yep. Here we go. Yeah, we're alright. Just gently, gently, gently. I'm just going to try and... Lift from the base? OK, there we go. Beautiful. Look at that. And the pot's in good nick. OK, that's OK. The canopy's fine? Yep, seems pretty good. Well, let's come and have a look at this. It's a bit root-bound. There's a real mat of roots. Now, that would have impeded some of the drainage. I think more importantly, if you have a look at the potting mix, just how gluggy it's become, and that's because the organic matter's broken down over time, and that really does impede drainage, and it means less air for the roots. So what we'll do is we'll pull some of this material away to make room, and we'll put it back into the pot for fresh mix, and so when the roots are growing, they're into that nice, you know, air-filled media, and the tree will do much better. But first, let's have a look at the old pot to make sure it's suitable for reuse. Right, well, this barrel's looking in decent nick, actually. The base is still solid, and those drainage holes can be made clear again. And the new mix that goes in will have much better porosity than the old gluggy mix. In extreme cases, when a pot is really root-bound, you can trim some of the roots with a pruning saw. In this instance, all we have to do is tease the gluggy soil free with our hands. With the size of the root ball reduced by around a third, it's a good idea to measure how deep it is so that the right amount of new potting mix can be put into the pot before lifting the tree in. The top of the root ball should be at least 50mm beneath the lip of the pot, with the graft well clear of the final soil level. Perfect, well measured. Spot on. Just a little bit that way, Josh. With the tree back in place, and after a quick check to make sure it's sitting nice and straight, we're back-filling with potting mix suited for citrus. It's got good structure and excellent drainage. Watering the soil in as we go, whilst gently rocking the root ball back and forward, will get rid of any air pockets and prevent the roots from drying out. Well that's the hard work done. It's looking good. Now it's time to give it a bit of a prune, because we have, you know, really disturbed those roots quite a bit, even though we're careful, it's important now that we reduce the size of the canopy to prevent the plant from stressing. So, it's a pruning job. I'll get started and then hand over to you guys to finish it off. OK. Sounds good. I'm reducing the tree canopy by about 20%. This will prevent the foliage from wilting after the root disturbance, and also encourage new leaf growth across the tree. The framework is pretty good, other than one crossing branch that needs to come out, to prevent it from rubbing and bruising the adjacent branch. So that's the major pruning done, and you can see we've reduced the height a bit, we've opened it up, we've taken out that main crossing branch. So all that's left is to remove this dead twiggy stuff, and there's quite a bit of it. And it is important to get rid of that, because it just congests things up, and as it rots it can be a point of disease entry into the tree. So it's now just a bit of finessing. You can grab that and just work through and cut out all the twigs. With the tree back in position, it's time for a feed. Citrus are hungry trees, so a top dressing of organic fertiliser is in order, along with an application of liquid kelp to help with re-establishment. And finally, a layer of mulch. Initially, Josie and Zave were quite daunted by this task, but as you've seen, through teamwork and a few tips, it's really not that hard. So Josh, do you think the patient's going to be OK? I reckon the prognosis is very, very positive. Well in that case, thank you very much for all your help, we really appreciate it. Thank you, Kumquat Marmalade. And I'm sure you'll be making much more next year.