Veggie raingardens

Funder: Melbourne Water

Researchers: Prof Tim Fletcher, Dr Claire Farrell, A/Prof Nick Williams, Dr Paul Richards, Dr David McCarthy (Monash University), Ms Minna Tom (Monash University)

Year: 2011-2013

Tomatoes in our veggie rain garden.
Veggie rain garden tomatoes.

Background

After a storm, millions of litres of water wash off our roofs and roads into stormwater drains. This causes large flows of stormwater into local waterways, damaging ecosystems. But using it for something productive – like growing your own veggies – can help keep waterways healthy and turn stormwater into a valuable resource.

In this project, we created veggie raingardens that produce food and retain stormwater to encourage more people to install them at home.

To test the performance of veggie raingardens, we conducted a greenhouse pot experiment to discover the best combination of soil and watering techniques for retaining stormwater and growing vegetables.

We tried different combinations of loamy sand raingarden substrate and a potting mix typical of container vegetable growing, and two methods of stormwater application (‘sub-surface’ and ‘surface’ watering). We used Melbourne’s average summer rainfall for each watering.

Key findings and recommendations

  • Raingardens reduce stormwater runoff and can grow healthy veggies.
  • The best planting solution is a mixture of 20-50 per cent potting mix added to biofilter sand, and diverting excess stormwater to other areas of the garden through a slotted pipe.
  • The ideal system for vegetable growth has a combination of surface and underground watering.
  • The down pipe option works best for the watering from below and the tank for watering from above.
  • The type of vegetable planted is largely irrelevant; they all produce a good yield.
  • Planting a variety of species can help to produce year-round crops.

Outreach

Resources

Are you interested in building your own vegetable raingarden? This instruction sheet from Melbourne Water will help to get you started!

Publications

Richards, P. J., N.S.G. Williams, T.D. Fletcher and C. Farrell (2017) Can raingardens produce food and retain stormwater? Effects of substrates and stormwater application method on plant water use, stormwater retention and yield. Ecol Eng. 100:165-174

Richards, P.J., C. Farrell, M. Tom, N.S.G. Williams and T.D. Fletcher (2015) Vegetable raingardens can produce food and reduce stormwater runoff. Urban For Urban Green. 14: 646-654.

Contact

For more information please contact Dr Claire Farrell from the Green Infrastructure Research Group at cfarrell@unimelb.edu.au.

Veggie rain garden beans.
Veggie rain garden beans.