"seldom spent" is correct and usable in written English.
It is used as an adverb to describe how often something occurred. For example, "He seldom spent his free time outdoors."
She seldom spent time at Medway.
I've seldom spent so much holiday in a kitchen.
Oh yes, he's full of faults and yet I think any fair-minded reader who applies to Isherwood the very approximate demands of life and not the overly exacting standards of fiction will have to admit that he or she has seldom spent so much time with someone so generally admirable.
Before this expedition, I had seldom spent much time looking at birds; in fact I had suffered three decades of acute bird blindness.
But in May 2014, 24-year-old Bulokhova and her boyfriend, Roman Troubetskoi, were in Amsterdam enjoying some much needed, yet seldom spent, time together during which, they conceived their son, Valentin.
In May 2014, 24-year-old Bulokhova and her boyfriend, Roman Troubetskoi, were in Amsterdam enjoying some much needed, yet seldom spent, time together, when the right side of her jaw began to swell.
Bright, ambitious young Americans seldom spend their whole lives making products with ballbearings in them.
I seldom spend much time with the front page of an issue of the Robesonian.
Johns Hopkins devoted himself entirely to the business, never traveling, never marrying, and seldom spending money on personal pleasures.
A dynasty like Wooden's would be almost impossible now, because the best players seldom spend more than a year or two in college before turning professional.
The interviewers are trying to juggle their day jobs with their recruiting duties: they seldom spend more than a minute or so reviewing each application form.
