Thursday, August 22, 2013

Grow Your Carrots in the Bath: How To Make A Wicking Bed

Published in Grass Roots magazine Dec/Jan 2015/2016 issue.

 It started in a tiny terracotta pot on a balcony that baked in summer. I planted some lettuce seeds. They grew to about 10cm high. And then they fried. Crispy lettuce anyone? My gardening skills have come some distance from my first attempt in that rental unit from my uni days. At the moment we are eating broccoli from the garden every night, salad, Asian greens, and we are still working our way through the Summer pumpkin harvest. But when it comes to carrots, there is a little window in winter when they happily grow for me, but the rest of the year nothing happens. The seed packet tells me they will grow all year round in our temperate climate. So are my gardening skills still as bad as my crispy lettuce days?

Last month I attended a workshop on wicking beds at Purple Pear Farm on the outskirts of Maitland. Even though they grow vege for a living, to my relief, it seems they were experiencing the same lack of carrots as I was. The challenge, we were informed, is that carrots have a very particular need for constant soil moisture levels. At germination carrots don't forgive you if the sun drys out their soil between your scheduled daily watering. The answer, build a bed that's self watering. You can even go on holidays and your carrots will still be happy.

Introducing the wicking bed. Here's how you can build one from an old bath tub, or two...

Wicking Bed Diagram: Construction can be from any waterproof vessel, such as an old water-tank, sink or in this case a bath tub. A water reservoir is created in the bottom with an overflow at right. The moisture naturally wicks up through the soil maintaining the soil at a constant moisture level. Perfect for growing carrots!

Step 1: Remove the drain hole and replace it in an inverted position. Build a frame for your vessel to sit on so that it sits at least 15cm above the ground to allow for drainage.

Step 2: Prepare 2 lengths of pipe as shown. The first screws into the inverted drain hole, with a hole drilled at the desired maximum water level for the reservoir. This creates the overflow. The second pipe receives water from above when the reservoir needs topping up. The holes along the bottom length of it evenly distribute the water into the reservoir. Ensure a cap is placed on the bottom end of it to prevent the water flowing straight through.
Step 3: Add some structure to the reservoir. Here old tree tube trays have been adapted to allow room for the pipes to pass through them. This creates a space below the soil for the water reservoir. Alternatively gravel or pebbles could be used. Ensure a valley is allowed between the sides of the bath tub so that the soil can enter the reservoir.
Step 4: Cut a length of geo textile to size and place in the bottom of the bath tub. Ensure there is ample overhang on the sides.
Step 5: Wrap Geo textile around the hole on the overflow pipe to prevent the entry of the growing medium. Secure it with a cable tie or similar.
Step 6: Pack the growing medium (in the case 'man sand' from the local landscape supplier is used) around the edges of the reservoir structure. Then continue to fill to the top.
Step 7: Your wicking bed is now ready for planting! Here is a successful bed of carrot and radish seedlings.
Step 8: Just in case the sun gets a little fiesty, it doesn't hurt to put a little extra protection in place. Here an old coffee bean hessian sack makes the perfect cover for carrot seeds that are yet to germinate.

The Wicking Bed workshop was kindly run by Purple Pear Farm, organised by the Hunter Organic Growers Society.

Read Seed Raising Workshop at Purple Pear Organics

1 comment:

  1. Thanks so much for posting this. This is just the information I need to use that neglected bathtub out the back.


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