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.

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

  1. Great article – thank you so much! I have two questions:

    1. Is it okay to use bore water in wicking beds?

    2. What is the typical lifespan of a well made and maintained DIY wicking bed in a wooden garden bed?

    Thanks!

    • Andrea, I have the same question regarding bore water, so I’m just dropping a comment here to be notified of the response you receive, thanks!

  2. I made a terrible mistake and accidentally left the outlet pipe in upright position, fully flooding my bed. It’s now a stagnant mess and everything has died. I am draining it now but I’m not sure what to do next or if it’s beyond salvageable. I would appreciate any advice as I really don’t want to empty and start again if can avoid it.

    Many thanks

    • Hi Kelly

      I’m surprised you had a full flood. Are you using a bed with a long riser pipe from the outlet? If so, that would explain it.

      Everything should dry out if you leave it. Happy to take a look at a photo so I can get an idea of what’s cooking.

      Regards
      Paul

  3. Hi I’m setting up a few wicking beds and have a heap of 20mm river rocks to use. Should I use them? I have heard they will not wick well as there is too much space between them.

    • Hi Greg

      That’s right, they won’t wick as such. That said, you will get some water moving up, and most people use scoria, which isn’t ideal for wicking. The best wicking of all is sand with flo-tanks. Costa (Gardening Australia), used to work for Atlantis and used this method.

      Cheers
      Paul

  4. I constructed 6 of my own 2.4m x 1m corrugated wicking beds 15 years ago as a novice. Having grown veggies magnificently originally, tailing off to quite well over the first ten years, there has been a five year descent to nothing growing at all now. 1/ How do I get them going again? Just add fresh soil/compost mix or remove all old soil and replace entirely? 2/ The design I followed had no drainage hole, just the recommended layers that I followed to the letter and PVC water inlet pipe. Is the absence of a drainage hole a likely contributor or is this the natural Hx of wicking beds. The soil is not overtly waterlogged.

    • Firstly, Bruce, let me congratulate you on building your own wicking beds and getting 10 years growing from them.

      The lack of a drainage pipe would likely affect the beds in 2 ways:

      1. Gradual buildup of unhelpful products in the pond, especially if you are using manures. These could possibly change the pH of the system, among other things.

      2. Waterlogging of the growing medium would certainly affect many plants.

      Solution (if feasible for you): add drainage. I prefer to have it at the TOP of the water line, in case I don’t properly seal it, in which case there is no loss of water.

      I would certainly replenish the soil. Veggie mix is the go-to for most veggie gardeners, although it can vary according to your nursery. Whatever you do, use well-composted manures only and spray any liquid fertiliser on the leaves. Fresh manures are too likely to put too many nasties in the pond.

  5. Hi just starting some research on the wicking beds and noticed that you mentioned to avoid using manures. Just wondering what the reasoning is behind that. We have chickens and would love to incorporate that into the garden beds, as well as horse manure. Thanks.

    • Hi Tammy,

      I avoid using fresh manures to avoid organic and other matter ending up in the pond part of the wicking bed and creating problems. We only add thoroughly mature compost (i.e. it won’t smell fresh), which can include manures as part of the composting process. I also suggest that if you want to use a liquid fertiliser, such as Seasol, you use it as a spray for the same reason as the use of compost rather than manure.

      Kind regards
      Paul

  6. Hello! Your information on wicking beds (and honestly your entire site) is very informative and helpful – thank you!! While I do not live in Australia, I do grow and donate to food banks in my own area. I installed 8 wicking beds this year and I have had amazing harvests! I am in the United States in an area that does having freezing temps in winter. I was wondering if you had any recommendations on if and how to winterize a wicking bed for winter/freezing temps? Probably should have thought of that before installing these beds, but here we are! I would appreciate any advice/thoughts you have!

    • Thanks for your kind words about the website.

      No, we don’t have anything helpful to say about winterizing wicking beds as it never gets that cold here in Australia.

      • I love the idea of wicking beds but hate the idea of using plastics – the liner and the geotextile which I understand is polyester. I’m particularly concerned about the geotextile shedding micro plastics? Are there any plastic free alternatives?

        • Unfortunately there are no workable alternatives to plastics at present. Various people have trialled using in-ground clay ponds, with limited success, but that still leaves the issue of the geotextile, which separates the pond from the growing (soil) medium. A non-plastic plastic is urgently needed in a huge range of applications. My car has a flax-based product replacing some of the plastics, and hemp is increasingly a likely replacement in some applications. Let’s hope the appropriate R and D gets funding!

          • Silk might work (4-5 years before it decomposes) or leather (10-50 years) or banana fibre (can’t find a definitive figure) – could be some interesting experiments.

        • I’m the same Penny, using plastics that can break down into nano plastics and get into the veggies you are growing would be terrible.

          I’m not sure about the actual IB C containers either.

  7. Hi thanks for a great article.

    Regarding lining – does the liner need to cover the entire internal surface of the bed (i.e. wherever there is soil) or does it only need to line the reservoir at the bottom (plus a bit to avoid soil loss down the sides)?

    • It is easy to underestimate where the water will find its way, so I always bring the pondliner to near the top. Water finding its way between the liner and the timber will pretty quickly lead to rotting of the timber (or rusting of galvanised iron). I can assure you that trying to repair a wicking bed sides is not fun!

  8. Hi there, thanks for the helpful article! I have 2 questions:

    1. I’ve read that ‘a few charcoal pieces spread about to limit anaerobic decomposition’ in the first layer above the geo-textile fabric is a plus. Can I use BBQ lump charcoal and do you recommend this?

    2. I was planning on mixing through manure into the soil layer but read elsewhere not to use manure. What are your thoughts on this?

    Thanks in advance.

    • 1. I have never had or heard of a problem with the anaerobic issue. Flushing the pond occasionally will help, as does allowing the water level to drop, which allows air in.

      2. One of the things which might impact aerobic levels in the pond of the wicking bed is organic material from manure draining into the pond. We always make sure that we add well-composted manures and seaweed foliar spray to avoid this issue. Fresh manures can be an issue generally in the garden.

  9. Hello.
    I’m in Brisbane Qld.
    Trying to find the black plastic liner.
    I need it 3m wide x 19 m long roll.
    Any suggestions.

  10. Hiya,
    We’ve taken over a property with a number of quite neglected wicking beds. I pulled the smallest apart to see what the previous owners had used and we have black plastic lining the bottom, sand which looks to have some algae or similar, geotextile fabric then soil. They each have an overflow.

    My understanding is that it’s been approx 5 years since anything was grown in them. And they’ve just been sitting there gathering weeds, inc. stinging nettle.

    Should I be pulling them apart and re-doing or will they be okay to use for a few seasons? Not sure if I should be concerned about the growth in the sand or if that’s part and parcel given the age of the beds?

    Thanks in advance,
    Amy

    • Hi Amy,

      5 years is a long time and wicking beds are somewhat pernickety. I would suggest ath you pull them apart and re-do them.

  11. Would this product work for the geotextile?

    “The Vigoro 4 ft. x 100 ft. Matrix Grid Landscape Fabric is perfect for all your landscape, hardscape, garden, planting, live goods, pathway, and soil erosion projects. The durable patented 3-layer technology utilizing a unique combination of a non-woven top layer, a matrix grid core center, and a non-woven bottom layer delivers a landscape fabric that is at least 2 times stronger than most fabrics. This unique technology allows for superior weed controlling along with air and water permeability that allows air and water to pass through the fabric to help maintain optimal soil conditions.”

    Do you, or can you, recommend a product by its brand or product name so that I can order it.

    • Hi John,

      We are not familiar with that particular product and, in any case, do not recommend partikcular products. Sorry.

  12. Should the geotextile fabric completely cover the waterups containers and up the sides to the top?
    Thanks.

    • Hi Linda,

      The purpose of the geotextile fabric is to let the water thru whilst not letting the soil thru. As such, the fabric has to be resting on whatever you are using for the wicking (and thus over the containers) but it doesn’t need to be up the sides.

  13. Hello
    I have a 2 concrete sleeves about 1.5m diameter I would like to turn into wicking beds. They have no bottom – it’s a section of concrete pipe (sleeve) that covers 2 ends of a concrete pipe. Could I turn these into wicking beds? Thank you.

  14. Hi,
    I am new at this. I am hoping to get a wicking bed made. Can I use concrete pavers instead of scoria?

  15. Thanks for the tips. Is it possible to recycle the water from the outlet back into a pond system?

  16. I think my new wicking bed is leaking as I have to keep topping it up every day. I cannot see any water around the bottom. I used pond liner and was very careful to avoid punctures. Does it usually take some time for it to stabilise or do I need to pull it apart and start again?

    • Hi Tony,

      It does rather sound as though you have a leak. The bed shouldn’t need to settle in. What size is the bed and how high did you bring the pondliner? I’d be happy to look at a couple of photos and give you my take.

  17. Such a helpful article! Thank you.

    My oregano has become invasive within the wicking bed so I’ve taken it out.

    Would this work: Plant it in a pot and sit the pot within the wicking bed to keep it under control. I’m picturing the roots sucking up water through holes at the bottom of the pot? Would the roots still run out of control?

    Thank you!

  18. I have read that it is OK to use old shade cloth instead of geotextile fabric- which you have to buy a lot more (costing more) than I would need. Is this OK?

    • Shade cloth is a poor substitute for geotextile (also sold as landscape fabric.) Geotextile is a single sheet (no weave), which is needle-punched, meaning water will pass through but no soil. It is used in road and other applications and does not deteriorate when covered. Shade cloth is usually woven, meaning there is much more room for soil to fall through into the pond underneath – not good. The good news is that geotextile is relatively cheap.

  19. I have just checked my water reservoir and noticed very very small white insect/bug attached to the wooden water dip stick. What should I do?

    • I’m a real newby at this. Could someone advise if i can still use 2 recently purchased empty ibc’s containing fungicide residue for wicking beds? Can I safely clean them without damaging either the environment or the potential planted crop inside?

      • Hi Penny

        Unfortunately I can’t give you a reliable answer on cleaning out your IBCs. I have ever only dealt with food-grade IBCs.

        Your best bet would be to talk to Sustainable Gardening Australia. They have an office at the back of Bulleen Art and Garden. If they don’t know the answer, I’m sure they will be able to find out.

        Kind regards
        Paul

  20. How foolish was I to use concrete aggregate instead of your recommended scoria? My plants are struggling after two years despite replenishing with compost. Could the concrete be leaching onto the water and into my plants?

    • Hi Ronald

      If the aggregate is stone screenings then it would not be a problem. If concrete screenings, that could change the pH slightly but shouldn’t be a problem if you are using good compost which will neutralise the effect. Check for leaks in case the plants are not getting enough water and fill at least once a week in cooler weather and 2-3 times in really hot weather depending on how high your plants have grown. For instance, tall tomatoes go through a lot of water and I re-fill our wicking beds every second day in the heat. If they are full or nearly full it doesn’t matter – at least we have made sure.

      Robin

  21. Do you think these would work for planting tropical plants and trees such as Thirsty Bangalow palms, tree ferns, bamboo etc? Obviously the bed would need to be a bit deeper and wider to accommodate a wider root system. Also what kind of soil should I use for this kind of setup?

    • I don’t think that it would work very well. As you say, the bed would need to be a bit deeper but then the wicking wouldn’t work to well.

  22. Thanks for the article, this is very informative.

    I’ve just been (trying) to build my Mum a few raised wick garden beds. Nearly there but we’ve hit a snag with the liner.

    I see you recommend not using builders liner. We are a little worried about leaching from any plastic that lines the wick bed, seeing as it will be in contact with both soil (on the sides) and water (at the bottom) for hopefully a long time.

    Is there anything you recommend?

    • Hi Tim,

      Bulleen Art and Garden has a food grade liner for sale. They also have cheaper PVC liner if you aren’t worried about it being food-grade. Also a company called Waterups, which specialises in wicking bed supplies, has a food-grade PP liner that they have just added to their website which is the most cost-effective one I’ve seen but maybe, once you add shipping, BAAG’s liner would work out much the same. Waterups also has 400mm x 400mm wicking planters made with recycled food grade plastic that might work for your mum. They are small enough to move around but large enough that you can fit a lot in them – like a blueberry bush or a couple of tomatoes and some basil or a whole lot of snow peas, etc. In terms of cost per square metre of planting space, they are pretty cost-effective compared to other modular systems and even some DIY ones once you factor in the cost of a container, liner and all the plumbing parts.

      The other style of wicking bed that I like is a half an IBC as you don’t need a separate liner, but I still use the waterups wicking modules for the reservoir as they store more water than using scoria etc.

  23. I too have some seedlings not growing. I believe they have not coped with the on-again-off-again weather we have been having and that they are stunted. My bush beans have grown to 8 inches, are flowering and producing stunted (half size) beans in small numbers. The walking onions planted in late autumn have done well in the same bed, the potato’s were waterlogged and dug early to save them but with reduced crop (222mm in October) whereas the purple Congo ones in the garden were dug 2 days ago and are large and healthy. The radish allowed to go to seed in the wicking bed has so few seed pods compared to what should be on it – poor pollination due to being too chilly in my opinion.

  24. Can I use pumice stone from the beach in the bottom of my wicking garden.

  25. Hi,
    With wicking beds, is it still ok to do compost and worm teas applied from top and watered in? Same question with foilar sprays?
    Thank you,
    Sam

    • Hi Sam,

      Yes, I think so.

      Note that wicking beds also benefit from some normal watering as this water the top layer which it is dfficult for wicked water to do.

  26. Hi
    I would like to make a wicking bed to put out the front verge of my house. It will be next to a bench seat which I am hoping to get shade. I don’t want to plant a tree in the ground as I might move the seat around from time to time and would like to move the pot with it. Do you have any recommendations of a plant which could be grown in a wicking bed? Pot is 800mm x 700mm x 900mm high. I have no access to water out the front so would like to use a wicking bed.

    • Hi Brian,

      Your plant needs to be shallow rooted. Most veggies and flowers are shallow rooted. If you want something bigger, my suggestion would be a lemon tree or other citrus.

  27. Hi I am wanting to make a wicking bed out of a big glazed terracotta pot. Do you think this would work? Also do you have to have an overflow pipe as this will stop this project. Cheers Cassandra

  28. 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.

  29. 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

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

  31. 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.

  32. 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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