The advantages, do’s and don’ts of wicking beds

 

Robin Gale-Baker, from Sustainable Macleod, discusses wicking beds. This is one of a series of articles she has written about growing techniques (see right hand sidebar). She has also written a number of articles about growing various vegetables, herbs and fruit trees.

The price of wicking beds has come down considerably in the last couple of years with the availability of corrugated beds with water tight bases. Corrugated beds do not need a pond liner, which is the expensive component of wicking beds made of macrocarpa, a salvaged wood. And they are ready made, saving on building costs. There are now so many advantages of wicking beds that they are well worth considering.

Advantages

  1. 50% reduction in water usage compared to an in-ground or raised equivalent size bed.
  2. Watering (place hose in inlet) only once or twice a week in summer, less in winter.
  3. Waist height for easy gardening especially for people with mobility issues.
  4. 4-5 crops per year compared to one summer and one winter crop.
  5. Plants can be grown closer together and roots will grow deeper.
  6. Consistent and constant moisture prevents damage to roots through drying out, especially important for tomatoes.
  7. Leaves resist scorching even in extreme heat. A fully hydrated plant will not scorch, though the fruit may get sunburnt.
  8. Grows spectacular root vegetable including carrots, beetroot, radish, parsnip, turnip and kohlrabi.

Don’ts

  1. Don’t try to build a cheap wicking bed – they invariably fail. Apple crates are cheap construction of unsuitable wood and deteriorate quickly. The nails become loose as well and can puncture the lining.
  2. Don’t use builders plastic or normal plastic if you need a liner. They are not strong enough.
  3. Don’t put in a bottom outlet in the belief that you should drain your bed. Years of experience have shown that wicking beds do not normally become anaerobic. If you do feel compelled to flush the reservoir, then simply fill the reservoir so that it overflows and flush out by hose. The downside, which I have seen a number of times, is that a bottom outlet will leak, causing your wicking bed to empty. Repair of this often means removing the sand and Flo-cells or scoria as well as the soil which is a time consuming, tedious and disheartening job.
  4. Don’t cut the geotextile lining which separates the soil from the reservoir to fit. It must come up the sides (like a bag) to contain the soil and not let it filter down the edges into the reservoir.
  5. Do not top-water, except for the first week if you have planted seeds or seedlings. These need, like conventional plantings, time to establish roots to take up water. Top watering can cause fungal disease by wetting leave sand splashing spores from the soil onto lower leaves.

Do’s

  1. Use a proven design. Water reservoir 300 ml depth, soil 250-300ml depth with inlet at the opposite end to the outlet. This is what works! Recognise that there has been much improvement in design by others since Colin Austin first invented wicking beds.
  2. Test your corrugated bed for water fastness by filling it with a couple of cm with water before proceeding to construction. If there is a leak, use a waterproofing compound to repair it and test again.
  3. Choose between using scoria, or flo-tanks (or similar) wrapped in geotextile surrounded by sand, in the reservoir. Scoria is cheaper but does not wick as well because of the size of the ‘rock’ and is a nightmare to dig out should something go wrong. Sand surrounding the flo-tanks wicks very well because of the small, dense particles it is made from but is more expensive when the cost of the tanks and cells upon which they sit are factored in (but much easier to remove).
  4. Use proper geotextile (not weed mat), to separate your soil and reservoir. Geotextile allows water to wick up but prevents soil dropping down into the reservoir.
  5. Use a good quality vegie mix for your soil – definitely not backyard soil! Add compost between crops but avoid manures.
  6. Remember to fill your beds once a week but check more frequently in a heat wave. The more growth you have the more water your bed will need as the bigger the plants the more water they need.

  14 Responses to “The advantages, do’s and don’ts of wicking beds”

  1. Thanks for this really helpful article. I have two questions:
    1. How do you recommend fertilising the bed if we shoudn’t use manures? Can we use seasol/fish emulsion?
    2. Also, when advice says a plant needs very well draining soil, does that mean it should not be grown in a wicking bed?
    Thanks very much in advance for your advice! I am somewhat of a beginner so I really appreciate it. I’m trying to read as much as I can, but am not sure about these points.

    • Hi Sarah – I’ll answer the questions on Robin’s behalf.

      In terms of fertilising, think more about maintaining a healthy soil. We use well-composted material – straw, grass, chook manure, etc – certainly not raw manures. You will find that this is more than adequate for a healthy crop. You can use foliar spray, but don’t tip liquid fertiliser on the beds – you’ll end up with it going into the pond. It does seem that the ready availability of water trumps the need for the fertiliser ‘big guns.’

      Your wicking beds should have a soil which is well-draining. Vegie mix that nurseries sell works well, but check that it has enough composted material in it.

      While we’re on the subject, I recommend sowing annuals, which you can grow and crop relatively quickly. This will give you the best return on your investment. Growing perennials and herbs (aside from annual herbs), really isn’t taking full advantage of your bed.

  2. Hi there
    Thank you so much for the article. I am about to set up my wicking beds and am starting with smaller styrofoam boxes 40 cm height. Can you suggest what veges do well in wicking beds and which veges do not require to be planted in them due to water requirements
    Warm regards
    Natasha

  3. Great article, Thanks Robin. can you grow aromatics in wicking beds?

  4. As an alternative to corrugated beds, Wicked Wicking Beds make IBC beds. See https://www.facebook.com/wickedwickingbeds/. We do deliver to Melbourne. Freight is far cheaper the more that we can do in a delivery. So if you can organise a few to order together then it will bring that cost down.

    • Hi there we have a bunch of wicking beds that work well. Just recently one wicking bed has started to die off with the plants still needing to produce veg. Water is full with no indication of loss of water , temp has been high and fert has been added. Plants still not happy . Wicking beds have good composted soil. Any suggestions

      • Hi Craig,

        Is the wicking still working? In other words, has the soil deep down still got some moisture in it?

      • I have the same issue in some of mine as well. Wicking is definitely still working. Seedlings from the same punnet planted in other wicking beds and also in my raised non-wicking garden beds are miles ahead. In the affected beds, plants seem to just be sitting there doing nothing. They have been regularly fed with Charlie Carp alternated with Seasol every month or so, but they just sit there and don’t advance. Tomatoes, lettuce, sweet basil and thai basil are in the beds at present, with eggplants in one of the others.

        • Hi, I am wondering if you found the problem with the growth of your plants in your wicking beds. I am getting ready to plant in a wicking bed for the first time.

  5. Great article, Thanks Robin. Is Paul still making wicking beds (for purchase)? Can you recommend any brands?

    • Hi Lucinda

      Paul is not making wicking beds having retired nearly 3 years ago. We ourselves have converted to the corrugated beds and love them. The manufacturer is ‘Rural Tanks and Garden Beds’ in Seymour. You can order them through either Bulleen Art and Garden or Nillumbik Nursery.

      You can also request that they come without a pre drilled outlet, and then put it in yourself at the top of the reservoir (where you want the highest water level to be).

      Robin

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