Plan staking and placement before gusty weather arrives. Compare pots and trellises using clear metrics. Adjust base weight or anchors until stability feels reliable.
| Time | Wind | Area | Height | Base | Mass | SF | Band | Extra ballast (kg) | Notes |
|---|---|---|---|---|---|---|---|---|---|
| No calculations yet. | |||||||||
| Scenario | Wind (km/h) | Area (m^2) | Height (m) | Base (m) | Mass (kg) | Notes |
|---|---|---|---|---|---|---|
| Tomato cage in pot | 45 | 1.20 | 1.10 | 0.45 | 28 | Leafy canopy, partial windbreak |
| Trellis with vines | 60 | 2.00 | 1.60 | 0.55 | 40 | Open yard, add ties to posts |
| Shade cloth frame | 55 | 3.00 | 1.40 | 0.70 | 55 | Use anchors; avoid sail-like panels |
This calculator estimates wind load and tipping risk using a simplified approach:
Higher stability factors mean a larger margin before tipping. Real conditions vary with turbulence, flexible stems, soil movement, and shielding from nearby walls or hedges.
Wind loading rises quickly because pressure scales with wind speed squared. The calculator uses q = 0.613 × V², where V is meters per second. As a reference, 30 km/h (8.33 m/s) gives about 43 N/m², 60 km/h (16.67 m/s) about 170 N/m², and 80 km/h (22.22 m/s) about 303 N/m². Use a gust value, not the daily average.
Projected area is the “shadow” the wind sees. A tomato cage with foliage might be 1.0–1.5 m², while a small trellis panel can exceed 2.0 m². Drag coefficient reflects how solid the surface behaves: leafy plants can be near 0.6, open trellises around 1.1, and solid panels up to 1.8. If pruning reduces area by 25%, wind force falls by roughly 25% at the same speed.
Overturning moment is M = F × h, so doubling centroid height doubles tipping demand. A 150 N wind force at 1.6 m creates 240 N·m, but at 0.8 m it is 120 N·m. Base width improves resistance because the weight lever arm uses b/2. A wider pot, ground frame, or outriggers can raise resisting moment without adding mass.
Resisting moment combines weight and optional anchoring. Adding ballast increases m × g, while ties and stakes add a resisting force that also acts through b/2 in this model. If the tool suggests 12 kg extra ballast to reach a 1.5 target, split it low and wide, such as sandbags around the base. Use anchors to limit sliding as well as tipping.
The stability factor is Mr/M. Values below 1.0 indicate tipping is likely in the chosen gust. Between 1.0 and 1.5 is a caution zone, where turbulence and flexible stems can reduce effective resistance. Above 1.5 provides margin for imperfect estimates. Recheck after growth spurts, soil moisture changes mass, or you relocate a container to a more exposed spot.
Use a representative gust for your location. If forecasts report gusts, use that value. For planning, test several speeds such as 40, 60, and 80 km/h to see how quickly stability changes.
Measure height and width of the wind-facing silhouette and multiply. For irregular foliage, estimate an effective fill percentage. For example, a 1.5 m by 1.2 m trellis at 70% fill is about 1.26 m².
Leafy plants behave more porous, often near 0.6. Open trellises with vines can be around 1.1. Solid panels, shade cloth, or plastic sheeting can approach 1.3 to 1.8. When unsure, choose the higher value.
Wind force acts higher than most of the weight, creating leverage. Raising the centroid height increases overturning moment linearly. Lowering the canopy, pruning tall growth, or moving loads downward improves stability without changing wind speed.
A target of 1.5 is a common planning minimum for outdoor setups. Use 2.0 when exposure is high or inputs are uncertain. If you store fragile items nearby, choose a higher margin.
Anchors can add resistance and reduce sliding, but they depend on soil strength and installation quality. Ballast improves stability regardless of soil. For best results, combine modest ballast with reliable anchors and periodic inspections.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.