Can Round Up Be Used on Flower Beds With Bulbs?

Only above ground plants with foliage are affected by Roundup.

Roundup is a popular herbicide in home gardens. Flower bulbs, like tulips and daffodils, go dormant for part of the year, which is the only time a flower bed should be treated with the herbicide so the foliage does not absorb the chemicals.

Chemical Ingredient

The active chemical ingredient in Roundup is glyphosate. It is a non-selective herbicide, meaning that it affects all plants that have foliage.

Vector

Glyphosate in Roundup is applied as a topical spray. Direct contact of the chemical onto living plant tissues, like those of leaves and stems, is required. Wind can drive spray onto nearby plants, causing damage from exposure to the chemical.

Soil

Roundup does not travel through soil.

Roundup does not travel in soil. In fact, soil acts as a buffer, protecting roots from harm. However, any above-ground foliage treated with chemical will absorb it and transport it to the rest of the plant.

Bulbs

Bulbs are underground living stems and roots of plants. If dormant, lacking any stem or leaf tissue above ground, treatment of an area with Roundup will have no effect on the bulb.

Seasonal Use of Roundup

Wait for all flower bulb foliage to disappear before treating the area with Roundup.

If your flower bulb is actively growing with either stems or foliage, Roundup will affect the plants and bulbs below. Therefore, treatment with glyphosate cannot coincide with the presence of above ground growth, flowering or seasonal foliage withering of the bulbs in the garden bed. Stems and foliage, unless fully dried and dead, must not be actively attached and transporting sap to the bulb. Treated foliage will then transport the chemical into the bulb in the soil and kill it.

References

• Cornell University: Glyphosate
• Glyphosate