Window box brackets: what to measure first
Updated: 22 October 2026
You have an empty trough on the kitchen floor and a balcony rail you have never put a tape on. This window box brackets guide is for that afternoon: you need to know whether a hook, a clamp or a screw-on 4-pack will take the box you already own, not whether the photograph looks like your block. The eight amazon.co.uk rows sit on the [flower box holder comparison](/hub/plant-accessories/flower-box-holder). Who each listing suits is on [best window box brackets](/hub/plant-accessories/flower-box-holder/sub/flower-box-holder-best). Washers, wing nuts and the dry-fit stay on [how to fit window box brackets](/hub/plant-accessories/flower-box-holder/sub/flower-box-holder-how-to-install). If the lease bans holes, read the [no-drill flower box holder](/hub/plant-accessories/flower-box-holder/sub/flower-box-holder-no-drill) page after you have the three numbers.
You have an empty trough on the kitchen floor and a balcony rail you have never put a tape on.
You have an empty trough on the kitchen floor and a balcony rail you have never put a tape on. This window box brackets guide is for that afternoon: you need to know whether a hook, a clamp or a screw-on 4-pack will take the box you already own, not whether the photograph looks like your block. The eight amazon.co.uk rows sit on the flower box holder comparison. Who each listing suits is on best window box brackets. Washers, wing nuts and the dry-fit stay on how to fit window box brackets. If the lease bans holes, read the no-drill flower box holder page after you have the three numbers.
Our top picks
| Badge | Product | Mount | Rail range | Box fit | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  TSKDKIT TSKDKIT no-drill balcony brackets, 2 pack | No-drill clamp | 1.5–32 cm | 15–23 cm | 6.4 | about £15.99 | View offer |
| Alternative |  Dandelionsky Dandelionsky 4-pack window box brackets | Sliding wall or rail | – | 18–23 cm | 6.9 | about £12.98 | View offer |
 Xclou Xclou window box brackets, brown | Two-fold hook-over | Up to 14 cm | About 10.5 × 21 cm | 9.1 | about £6.74 | View offer |
On this page
This is a holder, not a trough
A flower box holder in this comparison is a pair or a pack of metal brackets. The trough, the compost and the plants are separate. Listings that arrived as hanging pots, hanging planters, S-hooks or floral foam were cut from the set for that reason. If the title sells a pot that hangs from a rail, you are in a different aisle, even when the search box suggested this page.
UK shops sell the same idea under their own names. Wovar lists galvanised pairs from about £8 to £13 for boxes around 15–16.5 cm deep, sold per two. Boni Type B is £15.96 for a pair with a 25 kg pair load and a rail of about 14 cm. Lechuza’s BALCONERA holders claim 35 kg per pair and a circumference up to 32 cm, with the box sold separately. Those figures are shop references, not rows in the comparison.
The drainage holes sit in the trough, not in the bracket. The RHS container advice is the same on a balcony as on a patio: water has to leave the box, and a sealed tray will waterlog. Choose the holder for the rail and the box base. Choose the trough for the plants.
Three types in this comparison
The kept amazon.co.uk listings split three ways, plus one four-fold pack that behaves like a dearer hook.
Two-fold hook-over is the cheap rail job. Xclou brown is £6.74, 4.2 from 1,503 reviews, with 25 kg on the listing. Xclou anthracite is £7.20, 4.2 from 1,532, same geometry, no kilogramme on that listing. Both claim a rail up to 14 cm and a box about 10.5 × 21 cm. If your wooden trough is 20 cm across the base, this is the wrong type, not a colour problem. You hang them; UK buyers still add penny washers the bag does not list.
No-drill clamp is the renter job when you may not mark the rail. TSKDKIT is £15.99, 20 kg stated, 4.6 from four reviews, boxes 15–23 cm and rails 1.5–32 cm thick. Fastigeaty is £12.58 with the same size claim, no star line and no kilogramme. The Amazon field on Fastigeaty also says Floor Standing, which contradicts the railing bullets. Treat that as a listing clash, not a second product.
Sliding wall 4-pack is the owner job when you may screw a sill, fence or porch rail. Generic is £11.98, 4.1 from 22; Dandelionsky is £12.98, 4.4 from 17; Littleduckling is £12.98, 4.2 from 30. They share an 18–23 cm box line and a 40 lb claim. Bamworld at £19.99 is a four-fold 4-pack for rails 8.6–19.4 cm, with no kg on the spec. Leave the sliding packs if you cannot drill. Leave Bamworld if you only needed a £7 hook for a 14 cm rail.
Rail, box and load
Measure the rail thickness and the box-bottom width before you look at colour or stars. Xclou’s 14 cm ceiling is a different number from the clamps’ 1.5–32 cm jaw. A 20 cm parapet will not become a 14 cm hook because the listing says adjustable. The sliding packs do not print a rail thickness at all; they print an 18–23 cm box and assume you will bolt to timber or masonry.
Load units are not interchangeable. Xclou brown states 25 kg. TSKDKIT states 20 kg. The three sliding packs state 40 lb, which is about 18 kg as a listing claim, not a test. Boni Type B on the UK shop page states 25 kg per pair. Lechuza states 35 kg per pair. None of those figures is a drop test on this site. Wet compost in an 80 cm box can reach 20–30 kg as an ELEO Express rule of thumb, which already sits at or above several of the 40 lb claims. If the planted box will be heavier than the printed number, you do not close the gap by buying a darker colour.
Count brackets against box length. Two points hold a short plastic trough. Four points hold a long wooden or decking box; a 4-pack is two pairs only if you use all four. One UK text on Dandelionsky used the 4-pack on a five-foot decking planter. That is a length argument, not a reason to put four brackets under a 40 cm box.
What to count before you pay
Open the bag on the day it arrives and count wing nuts, bolts, plugs and brackets against the included line. Xclou’s set name says single while the included line lists two brackets. Generic’s bullets list hardware; one UK review still found four nuts and bolts missing. Fastigeaty’s pack-option bullets mention screws even while the no-drill line says no wall holes. Those clashes are buying checks, not footnotes.
Under the Consumer Rights Act 2015, section 22, you have 30 days from the day after delivery to reject goods that are faulty, misdescribed or unfit. Missing screws and a holder that will not take the stated box width sit there. Do not fill the trough first and then argue about a short bag.
Shelf prices in this comparison run from £6.74 to £19.99. Entry is the Xclou pairs. Mid-band is the sliding 4-packs at £11.98–£12.98, Fastigeaty at £12.58 and TSKDKIT at £15.99. Bamworld is the upper row here. Boni Type B at £15.96 is a named shop pair, not an ASIN. Lechuza is a branded system. Stars are not a substitute for the three measurements. Once the type is chosen, fit the empty box first, then compost, which is the sequence on the how-to page.
Common questions
What do I measure first, the rail or the box?
Both, before you open a colour swatch. Rail thickness tells you whether a 14 cm hook, a 1.5–32 cm clamp or a screw-on pack is even in play. Box-bottom width tells you whether Xclou’s 10.5 × 21 cm, the clamps’ 15–23 cm, or the sliding packs’ 18–23 cm is the window. If either number misses, the listing is the wrong type.
Will Xclou take a 20 cm wooden trough?
Not on the stated box fit. Both Xclou listings talk about boxes about 10.5 × 21 cm on a rail up to 14 cm. A 20 cm wooden trough is a clamp or a sliding 4-pack job, depending on whether you may drill. Buying the anthracite pair does not widen the geometry.
What does 40 lb mean next to 25 kg?
They are listing claims in different units, not two test results. Forty pounds is about 18 kg. Xclou brown states 25 kg. TSKDKIT states 20 kg. The sliding packs state 40 lb. An 80 cm planted box at 20–30 kg as a rule of thumb already sits on or above that 40 lb line. Compare the printed unit with the wet box, not with the star line.
Do I need to drill?
Only if you pick a sliding 4-pack or a pack that tells you to screw a wall or rail. TSKDKIT and Fastigeaty say no drilling. Xclou hangs over a rail; UK buyers still add washers. A lease that bans holes is a clamp job, not a cheaper 4-pack with plugs in the bag.
How many brackets for an 80 cm box?
Two points for a short trough, four for a long wooden or decking box. An 80 cm plastic box often sits on a pair. A five-foot decking planter in one UK Dandelionsky text used the 4-pack. Count the length of the box you own, not the photograph.
What if wing nuts are missing?
Count on arrival. If the included line promised them and the bag is short, the 30-day right to reject under section 22 of the Consumer Rights Act 2015 is the route, not a trip to a mixed-screw drawer after you have filled the box. Generic’s UK file includes that missing-bolt case.
Is a hanging basket a flower box holder?
No. A hanging basket, hanging pot or floral-foam cage is a different product. The holders here carry a separate trough on a rail, wall or fence. Search suggestions that mix the two are why those misfits were deleted from this comparison.
Related pages
Sources
Public UK sources used for this comparison. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these eight listings. Last checked 19 October 2026.
- RHS, Roof gardens and balconies (retrieved 19 October 2026)
- RHS, Growing plants in containers (retrieved 19 October 2026)
- Consumer Rights Act 2015, section 22 (retrieved 19 October 2026)
- GOV.UK, General Product Safety Regulations 2005: Great Britain (retrieved 19 October 2026)
- Leasehold Advisory Service, Alterations (retrieved 19 October 2026)
- Boni Shop UK, Type B holder (retrieved 19 October 2026)
- Lechuza UK, BALCONERA holders (retrieved 19 October 2026)
- ELEO Express, Attaching flower boxes (retrieved 19 October 2026)