Nice work! Difficult in Canberra where periods of frost and growth of flower spikes intersect. We need density to protect from frosts, so hard cut late Summer so Autumn growth protects again.
You will be surprised how well they will come back from the severest of hair cuts. At Austplant we did ours about 6 weeks ago and they are covered in new growth. IMHO a better time to cut them back would be in Spring when the weather and soil is starting to warm. Giving them a feed with something like Troforte at the same time is also a good idea.
@Ed I would suspect that your Kangaroo Paws may be hungry and a good feed with a low phosphorous fertiliser may be in order. @Austplant.NativeNursery we use #Troforte which the Kangaroo Paws respond particularly well to. Not also that the flowers of Kangaroo Paws are long lived on the plant do naturally fade over a period of months. Cutting back as you see in the video will obviously remove the spent and faded flowers.
The are relatively hungry. Drainage could also be an issue. Ironically the problem is likely the same. Poor drainage leads to root damage and poor nutrient uptake. If you can improve the drainage issue (ie with gypsum) and give them a feed then the issue will most likely be solved.
Trim the whole plant's foliage down by 1/2-1/3rd. Take it out of its pot, loosen some soil around it so you can see the rhizome structure. Grab a clean bread knife and Cut it into some clean sections, you want a healthy clump of foliage growing from each section. Then just repot in well draining soil as you desire. Give it more water than usual for a week or two. @@marilynneedham570
You can usually pick off some of the outside plant-lets and pot them on successfully. The issue with many of the smaller growing varieties is that they tend not to live all that long.
I no longer work at Austplant but this still my channel. (Currently working at Southern Plants - southernplants.com.au/ and we grow a lot of Kangaroo Paws!) Now is a good time to be cutting them back in SE Australia. Follow up with a good feed with a decent slow release native fertiliser and regular water.) The other option if you have the time is to just remove the flowering stems as low as you can. I macho approach is much quicker ;-)
I am no longer at Austplant but now work at southernplants.com.au (also insta and FB) who grow 100k plus kangaroo paws per year. The rain should not be a problem as long as drainage is good. I would hold off on cutting back until after the danger of frost has past and then do the deed. Give them a good feed when the weather starts to warm.
Ideally in early Spring when the weather is about to warm. Pruning encourages growth so it helps to have good growth conditions (warmth, sunshine, moisture and nutrients) available soon after the cutback.
You will find that the shorter stemmed varieties such as Bush Gems are also short lived which is why we do not sell them @Austplant.NativeNursery. I doubt you will find these as seeds. We also sell Kangaroo Paw seeds. One packet contains a mix of the taller growing varieties and the other just Anigozanthos manglesii.