Nothing matches all of those filters.
Weight and size boosters
The concentrates that go in through the middle and the back end of the cycle.
PK boosters
Phosphorus and potassium on their own, for the weeks when demand for both peaks.
Stimulators, tonics and sprays
Working on the metabolism rather than adding raw NPK.
Sugars, flavour and aroma
Carbohydrates, and precursors for essential oils and pigments.
Organic flowering tonics
Plant and mineral extracts for soil and living media.
Late-cycle finishers
Used in the closing weeks, once nitrogen comes out of the feed.
The full range
Flowering boosters for bigger, denser flowers
This is the widest range on the site — dozens of products from over 30 brands — because the final six to eight weeks of flower is where most growers spend their booster budget. PK boosters supply extra phosphorus and potassium for flower and resin production, while carbohydrate and terpene products like Atami Bloombastic or House & Garden Bud XL feed the plant's own sugar production in the last stretch.
Most PK boosters run from week 3 of flower, often at a low starting dose (1-2ml/L) rising to full strength by mid-flower, then tapering off in the final one to two weeks before the plain-water finish. Shogun PK Warrior 9/18 and Mills Ultimate PK are straightforward single-additive PK boosts; Advanced Nutrients Big Bud and Big Bud Coco are formulated for their own media type, so check which one matches your grow before buying.
Ranges worth knowing
- Atami — Bloombastic, Blossom Builder, Coco Bloom Stimulator and Rokzbastic, a Dutch range built around big, resin-heavy late flowers.
- Canna and BioBizz — Boost Accelerator and TopMax, both mid-range single-bottle additions that pair with any base feed.
- Mills, Shogun and House & Garden — Ultimate PK, PK Warrior 9/18, and Bud XL and Top Shooter, three different approaches to the same last-weeks push.
Don't stack more than two or three flowering boosters at once — total EC adds up fast in coco and hydro, and more isn't always better once the plant's ceiling is reached. Check your pH and EC control kit is calibrated before flower starts, and see enzymes & other for root-zone cleaners to run alongside a heavy PK schedule.
Free UK delivery over £60, Express Delivery available. Call 020 3488 0419 if you want a hand picking the right booster.