Fern Cobble

Fern Cobble

Posted on 17 May, 2008 1 comment

A friend asked me what a Fern Cobble was… here I go again fishing back into my geriatric memory… I knew the subject in detail thirty-odd years ago, but now I have to pause and consider.
So, after rifling through my files and disturbing ancient dust I found a publication of the Brooklyn Botanical Institute… Turns out the pamphlet I found was one of two that I owned… The one that I still have is not the one I wanted…I remember lending it… I never got it back…oh well…
A fern cobble is a construct that is buried in the soil to hold ferns in place while they establish themselves… usually on a less than level site or one with questionable drainage.
landscape fabric staples are used to anchor a layer of chicken wire which is placed over a layer of unmilled spagnum which has been layered over a prepared bed of loamy organically rich soil.
The upper layer is more of the compost rich soil…then the fern crowns are placed so that they sit above the soil and any roots will spread through the soil and spagnum… some books suggest using black plastic as a base with pea gravel… I find pea gravel too heavy…I prefer using wire staples that can be fixed to the chicken wire to hold the crowns in place. As under planting, until the crowns ‘take’ try oxalis, or ajuga or some low growing ground cover that will help retain moisture. Keeping moisture levels perfect for the ferns is a challenge at first but a mister or a drip hose work.
Ferns spread by spores…check out the underside of the leaf and if spores are present (yellow dusty cups) bend the frond to the ground and secure with a landscape staple. Keep moist and check for new ferns!! To ensure that roots stay well buried top dress with compost/soil once or twice a year.
Ferns are relatively pest free and they will exist happily in deep shade…but there are different ferns so make sure you know which type you’re growing. Ferns are sensitive to salt beware of animal urine…(dogs/cats) and salt use in winter on sidewalks or streets.
So …there it is my friend.. hope it’s of use.

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