The Rotary Power Harrow by Jean Martin Fortier

by Jean-Martin Fortier

Like I mentioned in my first blog post, in our garden, the equipment of choice for bed preparation is a rotary power harrow (often just called a power harrow). On this tool, multiple sets of tines rotate on a vertical axis, which till the soil horizontally. The result is that soil layers are not inverted (which is useful in preventing dormant seeds from being worked up) and no vertical compression of the soil that can lead to hardpan formation.

Its “stirring” action does not over-pulverize the soil such as can be done with a rototiller. Also the depth of soil working can be incrementally adjusted allowing for surface bed prep on 1” to 5” depth. It comes with mounted mesh roller that levels and pre-tamps seedbed for precision seeding and good seed-to-soil contact.  All and all, the power harrow favourably replaces a rototiller mainly for the fact that it perfectly conditions the soil for transplants and direct-seeded crops while leaving the soil structure in better shape.

   Multiple sets of tines rotate on vertical axes totally horizontal tilling of the soil.  

Our power arrow is made in Italy by the small company R2 Rinaldi. We’ve been using it intensively for more than 6 years now without any problems at all. Its rugged, heavy duty and built for commercial usage. We got it from EarthoolsBCS and paid about $1800 for it. If there is drawback to it, its that it is a heavy implement (it weights 210 lbs !), making it more challenging to maneuverer than a rear-tine tiller. Placing a front weight (dumbbells for example) can offset some of this and help balance the tool for it to work more easily.

The other thing is that your walking tractor will need to have are long enough handle bars to allow foot clearance when using the harrow.  Our first BCS (walk behind tractor) was a 732, which didn't quite work out because of the shortness of the handle bars. We therefore had to change it for 852, which overall, is just a better all around walking tractor. I don't know about Grillo’s (another similar type of walk behind tractors) or other brand, but its definably important to inquiry about this before committing to a purchase. For usage of the 29 inch power harrow (which is what you want if working on standardized 30 inch beds) minimum tractor horse power will need to be 12 hp for gas engines and10 hp for diesel.

The Power Harrows is by far the best tool I’ve used for seedbed preparation and I would definitely recommend trying it first before adopting any other tilling or spading device.  

Should you be thinking of purchasing a power harrow for your market Garden? And if I’m a new farmer, at what point do should I consider this? 

I often get asked the question of whether one should be considering the purchase of a power harrow for a market garden and if they are a new farmer, at what point should one consider.  Given that a power harrow is more than twice the price of a regular tiller, it deserves some deliberation.

We opted for a horizontal soil working device for its long term benefits on the soil. Although a rear-tine tiller is practical, its use ruins the soil structure every time. The rear-tine will pulverize the soil, leaving it nice and fluffy for a short while, but by doing so, breaks up soil aggregates, leaving the soil to eventually settle into a more compacted state. The weight and action of the tiller also causes a hardpan below where the tines reach, further decreasing soil drainage and the ability of roots to penetrate the soil. In an bio-intensive system, were soil structure is the prerequisite for close spacing of the crops, these side effects are problematic. I know for a fact that given the abuse a tiller can have on the soil, if used 2 to 3 times yearly (we do a lot of succession planting in our market garden) for more than 3 to 4 years, would have ruined it.

This being said, if on rented land or if using a tiller for only a couple of years, its not that problematic (except for the weeds seeds that you keep bring up !) When first starting out, the important thing is to be successful at growing vegetables and a tiller can nicely do the job of preparation sed beds. However, If the idea of minimal tillage eventually inspires you, then a power harrow might be the perfect tool for the job. 

Even though the power arrow is a heavy implements, is not that weighty and everyone in our  gardens can use it. (I’ve briefed about not saying “even girls”  so I didn't!)

Jean-Martin Fortier is the founders of Les Jardins de la Grelinette, an internationally recognized micro-farm known for its high productivity and profitability using low-tech, high-yield methods of production. He farms with his wife in Southern Québec, Canada

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