Prom 29: NYO, Gardner/Prom 30: Kolesnikov, NYOS, Volkov

If the BBC were to plan a Proms season exclusively devoted to youth orchestras and ensembles, many of us would be delighted. Standards are now at professional level right across the board.

20 years ago, the National Youth Orchestra of Scotland (★★★★★) couldn't compare with its Great British counterpart; now, although the age ranges are slightly different and the (or should that be the) National Youth Orchestra (★★★★) has vast wind and brass sections, playing levels appeared equal. It was only the matter of a conductor's questionable interpretation in the first concert and a superlative soloist in the second which gave the overall palm to the Scottish team.

Let's get the major disappointment out of the way first. This was another mixed bag for Edward Gardner with the NYO following their razor-sharp Stravinsky Petrushka and comparatively blurred Lutosławski Concerto for Orchestra at the 2014 Proms. Gardner simply didn't seem to know what to do with Richard Strauss's Also sprach Zarathustra, part of an interplanetary programme courtesy of what Stanley Kubrick made of its first minute in 2001: A Space Odyssey rather than anything galactic in the composer's poetic homage to Nietzsche.

Nevertheless it struck me for the first time that the Holst of The Planets, featured here in the NYO's second half, may have known his Strauss, not least in some of the low wind colours, the punctuating use of the organ (the Albert Hall leviathan played here by 14-year-old Joseph Beadle) and the final incandescence. Quite why Gardner was able to encourage space and magic in 'Venus, the Bringer of Peace" and grandly conceived terror in "Saturn, the Bringer of Old Age" when he found none in what should have been the big billowings, the joys, passions and Night Wanderer's Song, of the wacky 1895 tone poem baffles me. Gardner's Zarathustra was over-driven throughout, only occasionally startling as the 12 silky double-basses launched the famous fugue based on all 12 notes of the chromatic scale (one of the first tone rows, in short, though Bach and Mozart have them, too). Jonathan Nott made it all fly with another young team at the Proms, the Gustav Mahler Youth Orchestra; by comparison, this was an interpretative black hole.

Gardner (pictured above with NYO strings) did, on the other hand, seem to love and understand his Holst. The very distinct character of each planetary humour reached two dancing zeniths in an incomparably brilliant "Jupiter" and the terrifying romp of "Uranus". Colin Matthews's otiose addition of a Pluto piece - that planet was only discovered four years before Holst's death - offers nothing new, soundwise, and lacks the thematic hooks of the master. It did only one service here: to move us on from some dodgy tuning in the final wordless chorus, always a treat wafting down from the Albert Hall Gallery but treacherously high and probably not suited for young ones such as the CBSO Youth Chorus. Inchoate, too, was the opener, Iris ter Schiphorst's Gravitational Waves, fun though it must have been for the players to don black and white masks, for the strings to be amplified, and educational for us to contemplate a piece based around the "chirp" sound emitted by the circling of two giant black holes. Loud at times, yes; cosmic, no.

Soundworld wise, we heard nothing new in the second of Helen Grime's Two Eardley Pictures - Snow - at the start of the NYOS concert (read Alexandra Coghlan's review of the first, Catterline in Winter,  here). I love the paintings and their originality, but it's hard to detect any poetic links in music that's percussion-spangled and twittery like a hundred other new pieces. Its virtues, apart from the clearly well prepared performance with its strong rhythmic undertow, are Grime's characteristic concision and the moody two- and three-part string writing which, if anything, is at the core of the work (the composer pictured below with conductor and players).

This was as vivid an interpretation of Stravinsky's complete Firebird ballet as we're every likely to hear in the Albert Hall. Not as quirky, perhaps, as Kristjan Järvi's unpredictable flaming with the NYO at the Festival Hall earlier this year, but Volkov knows exactly how to keep the first half from exotic torpor, and there were some wonderful orchestral solos along the way, with the first horn a match for her counterpart in the NYO the previous evening. And it's a big claim, but I've never heard a principal flautist in any orchestra more full-toned and agile than Graham Dickson, making his mark earlier in the Tchaikovsky Second Piano Concerto. This was a revelation shared between Volkov, who stripped away any imperial grandeur in favour of bright energy, and his astonishing pianist, 27-year-old Pavel Kolesnikov.

Kolesnikov can do everything this colossal masterpiece requires - the thunder and the double octaves, the flyaway transcendentalism, but above all the imaginative poetry which made his two huge cadenzas in the first movement coruscate with unique ebb and flow. He rightly kept a low profile in the one-off slow movement. Its extensive solo roles for violin and cello used to be cruelly cut in the pointless abbreviation of selfish piano virtuoso Alexander Ziloti, but their final trio-union with the pianist is worth waiting for, and here came out of a central section of genuine threat and distress. Here Ye Ye Xu and Findlay Spence were rightly in the limelight; I'm sure NYO leader Millie Ashton was equally good in her important solos the previous evening, but from my seat, and given an extra desk of first violinst, she was turned too far away to register.

Tchaikovsky's adorable finale was taken at a daring lick, but Kolesnikov dropped no stitches and managed the chuckles as well as the heartsurges with perfect clarity. His encore took us from G major to G minor, and a poignant lowering of temperatures if not emotional content, the rising scales of "June" from Tchaikovsky's The Seasons. Full tone and distant voices alternated with perfect instinct, setting the seal on a young pianist who is already one of the best in the world. And his concerto performance blazed such a trail that it left Tchaikovsky Competition winner Dmitry Masleev in the First Concerto earlier this summer stranded in the dust. Trifonov and company need to make a place for Kolesnikov in their august company; he's more than ready.

• Listen to the National Youth Orchestra Prom and NYOS concert for the next month on the BBC iPlayer
• Read more Proms reviews on theartsdesk