Consumer advocacy teardown
Plant Invigorator & Bug Killer alternative & active ingredient dupe
Stop paying £14.99 for SB. The bulk active is Horticultural potassium soft soap — 53% less per working litre than a typical pack.
- Active
- Foliar urea and alkyl surfactants
- CAS
- 57-13-6 / 61790-44-1
- Dupe
- Horticultural potassium soft soap
- Saving
- 53% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
The Marketing Claim & The Catch
A typical 500 millilitres pack of SB Plant Invigorator & Bug Killer is about £14.99 in lawn & garden. That is a snapshot, not a live Amazon price — listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Physical pest control for aphids, whitefly, spider mites and mealybugs; and Foliar nutrition while checking powdery mildew.
The catch: Dilute foliar urea plus a potassium fatty-acid soap that smothers soft-bodied insects. A 500 ml bottle at 10 ml/L makes about 50 litres; the same working spray from bulk soap and urea is pence per litre.
- “Physical pest control for aphids, whitefly, spider mites and mealybugs”
- “Foliar nutrition while checking powdery mildew”
Proprietary Blend & Dosage Breakdown
The labelled active is Foliar urea and alkyl surfactants at 5%. Everything else in the pack is water and chelating agents.
At 5% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 100% Horticultural potassium soft soap, mixed to 10 ml soap + 5 g urea per litre.
- Labelled active
- Foliar urea and alkyl surfactants
- 5%
- Carrier
- Water and chelating agents
- Retail pack
- 500 millilitres · £14.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Horticultural potassium soft soap at 100% bulk. Indexed as CAS 57-13-6 / 61790-44-1. Buy it as 1 litre soap (plus 1 kg urea in the stack) for about £13.50 from Amazon UK.
Working strength: 10 ml soap + 5 g urea per litre. Indicative cost £0.14 per diluted litre — 53% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Mix 10 ml of potassium soft soap into 1 litre of warm water in a trigger sprayer, then dissolve 5 g of soluble urea.
- Spray both leaf faces in the morning. Physical smother — repeat after rain. Avoid hot sun on thin foliage.
- 1 litre of soap at 10 ml/L makes 100 litres of spray (use about 500 g of the urea bag).
- Do not mix with foliar copper or strong oxidisers.
Mixing desk
Dilution calculator
Switch between filling a sprayer and covering a measured surface. Figures are educational estimates from the listed ratio — always check the SDS.
Formula
Horticultural potassium soft soap
- Concentrate
- 10 ml
- millilitres of liquid
- Water
- 0.99 L
- carrier volume
- Batch cost
- £0.14
- 1 L working solution
- Saved vs retail
- £29.85
- 100% · retail £29.98
Estimated coverage at the listed rate: 8 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedSB | Raw active dupeDupeStack |
|---|---|---|
| Product | Plant Invigorator & Bug KillerAmazon UK search — listing, not a confirmed seller | Horticultural potassium soft soap |
| Pack / unit | 500 millilitres · £14.99 | 1 litre soap (plus 1 kg urea in the stack) · £13.50 |
| Active | Foliar urea and alkyl surfactants at 5%Carrier: Water and chelating agents | 100% bulk— |
| CAS number | Not disclosed on pack | 57-13-6 / 61790-44-1 |
| Working strength | Ready-to-use pack | Dilute 10 ml soap + 5 g urea per litre |
| Cost per litre | £29.98 / L typical pack | £0.14 / L mixed from bulk |
| Headline saving | Baseline | 53% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectacles |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in SB?
SB Plant Invigorator & Bug Killer is labelled as Foliar urea and alkyl surfactants at 5%. The carrier is Water and chelating agents. Pack size: 500 millilitres. The bulk equivalent we index is Horticultural potassium soft soap (CAS 57-13-6 / 61790-44-1).
Is Horticultural potassium soft soap safe on lawns?
Used at the listed working strength (10 ml soap + 5 g urea per litre), the dupe is the same chemistry as the branded pack for lawns, beds and pots. That is not a blanket all-clear: read the supplier SDS, wear the listed PPE, keep acids away from hypochlorite, and follow UK HSE/COSHH rules. Wellness teardowns are supplements, not medicines.
Is there a cheaper alternative to SB Plant Invigorator & Bug Killer?
Yes. The bulk equivalent is Horticultural potassium soft soap (CAS 57-13-6 / 61790-44-1). Indicative saving 53% per working litre versus a typical £14.99 pack. Working strength: 10 ml soap + 5 g urea per litre. Live shop prices move.
How do you mix the Plant Invigorator & Bug Killer dupe stack?
Mix 10 ml of potassium soft soap into 1 litre of warm water in a trigger sprayer, then dissolve 5 g of soluble urea. Spray both leaf faces in the morning. Physical smother — repeat after rain. Avoid hot sun on thin foliage. 1 litre of soap at 10 ml/L makes 100 litres of spray (use about 500 g of the urea bag). Do not mix with foliar copper or strong oxidisers.
DupeStack provides chemical concentration data and educational mixing guides. Always review official manufacturer Safety Data Sheets (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Some links on this site are affiliate links.
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DIY stack · 53% / L vs branded
£22.50indicative kit · Amazon cannot add a mixed search kit as one basket