He says succulents are "friendly and architectural" rather than "spikey" cacti, so appeal as they are "forgiving" to inexperienced gardeners.
However, he says there are no other UK wholesalers of any size and the main suppliers are Dutch wholesaler Edelcactus and grower Kwekerijj Ubink, but even they have demand-driven shortages of young plants, which come from Italy, the Canaries and North Africa.
Plants take 18 months to reach saleable size.
Pugh, who grows on hundreds of thousands of cacti and succulents a year, says echerveria, haworthia and crassulas are most in demand. He supplies clothing retailer Urban Outfitters with plants, which he says suit the 20-something "lifestyle" image of the company.
Pugh says the trend, driven by the internet and social media, has two or three years to run but he adds that some garden centres "aren't on the ball".
Wholesaler Javado says many of its hundreds of retail customers have doubled sales. Javado says no-one has had increases of less than 10%. A 30-40% increase in sales is "standard". Succulents, aloe vera, monstera, fiddle leaf fig, some ficus and any jungle-style plants have done best.
Javado's James Woodham says "phenomenal" sales of foliage houseplants are overtaking flowering houseplants for the first time, after previously being traditionally at a 70-30 level.
Dobbies, the UK's second biggest garden centre chain, has seen sales raise by double digits this year.
Klondyke said they had seen similar growth. Buyer Andy Smith said they have been "very strong this year. The growth area is succulents and cacti where we have seen double digit growth. At present they are very on trend and feature a lot in lifestyle magazines. Airplants have seen great growth too."
GCA chief executive Iain Wylie said 2016 saw higher percentage growth among members than this year but 2017 was also positive. Houseplant sales were up 7.31% in June compared to the same month last year with a year to date change of 2.38%.
He wondered if M&S and supermarkets had taken more than garden centres from the trend. He says customers are now keen to buy plants than cut flowers, because they last longer are are seen as greener.
Wylie says any category can grow if a retailer commits to it and there are opportunities to be seized in houseplants, that some centres may not have taken, unless they have changed the way they display indoor plants from how they showed them a decade ago.
#Alys Fowler has written Plant Love (Kyle Cathie) about how to nuture houseplants. She says garden retailers need to stock more "elegant pots" to service the trend for succulents and houseplants generally. "I think the market for plants is doing well and there’s a healthy amount of choice around plants, but elegant, simple pots seem to be very much lacking still. That all the stuff that goes around houseplants, attractive small watering cans, nice hooks for hanging plants, nice hanging baskets for indoors for that matter too. No one really wants to hang their great looking plants in a naff plastic pot."
And as for UK nurseries, they could get involved too, with the proviso that the economics of competing with the global market would need deep research. Former Horticulture Week writer Fowler said: "It seems that if you can grow poinsettias or heat requiring bedding plants you could probably corner the houseplant market."