Thursday, February 10, 2011

Green Roof Tale of Two Turnips, Rooftop Garden v. Ground Level Garden

Green and living rooftop gardens have important advantages over ground level gardens. Some of these advantages are important to the quality of the garden vegetables being grown and the amount of produce ultimately harvested.

A living and green rooftop garden can offer the following benefits;
  • More light
  • Certainly more direct access to dew, fog and rainwater
  • and important one we will discuss today - if clean soil is used originally then there may be isolation from ground level pests on the rooftop.
The following photo was taken yesterday, February 9, 2011 in one of the many ground level gardens here on our Urban permaculture plot.  The turnip leaves are skeletalized by the feeding of an unknown pest - we suspect a moth worm of some type (diamondback).

First, it is important to note here;
  • All native insects have a purpose and are beneficial
  • Providing the correct garden conditions can greatly reduce the onset of insect attack, 
  • Rooftop and green roof gardening provides important benefits to the soils and plants that help alleviate insect infestation, and
  • Plants succumbing to insect attack may be dealing with a mineral, nutrient, air pollution or water quality issue.
Pest damage to the ground level garden turnips

We practice organic gardening on all of our ground level gardens and rooftop gardens.  We practice organic gardening because we have witnessed the massive quantities of chemicals standard agriculture methodology applies to soils and vegetables.  But we do live on an Urban Core lot, in the middle of one of the largest cities size-wise in America, and our neighbors may or may not treat their soils and gardens with the care we do and subsequently may or may not have pests looking to come feast on our organically grown gardens.

In preparation for growing, say turnips or mustard greens, many farmers and city gardeners apply massive amounts of herbicides to the soils to keep the native herbaceous plants down, followed by many different types of highly toxic dusts and powders to keep insect damage to a minimum.

Consumers do not witness the poison applications first hand as they got o the market and purchase, big, leafy greens pumped up with chemical fertilizers and saved from the insects, not by smart planting and soil health practices, rather saved from the insects through constand dousings of highly toxic killer substances. 

Then we wonder why we feel so tired and lethargic.  A substance that kills bugs will affect humans too, just takes a little more sometimes.

But the good news is green roofs and rooftop gardens make a difference!

The following photo is of the greens on one of our rooftop gardens, also taken yesterday.

Rooftop greens, extensive green roof garden, Jacksonville, Florida

As you can see, there is no pest damage.  The greens are spared from the insects.

Why?  We can offer up several reasons.

  • Rooftop permaculture gardens are open to the birds for insect scavenging
  • Rooftop garden soil media becomes hotter than ground level soils and may 'self-sterilize'.
  • Green roof vegetable garden receive strong amounts of healthy sunshine
  • Rooftops are high up off the ground and many soil insects may not be able to reach the rooftops.
Importantly, when constructing a green roof, it is important to use clean or sterile soil media to prevent the import of insects, fungi and other potential pest organisms.  Additionally, check the plants you use.  If you want to feed you and your family on chemical free vegetables then start your own vegetable plants from open-pollinated, non-GMO seeds.

Often, vegetable starts purchased at your local retail store are 'pumped up' with lots of fertilizers and other substances to make them look beautiful so they will sell easily.  Once you plant these steriodized young plants in the garden or on the roof they go through shock and many die.  So consider starting your own plants from seeds - they will grow better in the long run.

Rooftop garden requires some planning though as your vegetables will be subject to certain conditions not found on the ground.  We've discussed these in previous posts and will do so again, so stay tuned here.

Consider the possibilities! 

I believe we can feed the world with truly healthy food grown on the rooftops.

As always, we appreciate your comments and emails.

Happy green roofing!


1 comment:

JB said...

quite amazing to read on a rooftop permaculture website how to start a STERILE garden! i think permaculture is not about avoiding insects and pests but about generating a rich biodiversity that is robust for pests!