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How much rain/water is enough?

I have a lot of pots in my small garden, so watering is unavoidable. But I offen wrestle with it: I water and then it rains, or I don't because rain is promised, but then it doesn't show up.

I quite often water my flowerbeds too, since they are not very well established and there are always new things going in. Plus it's a very shady garden and it's hard to find flowers that will thrive, so I'm not willing to take the approach that they have to manage on their own or they don't belong. 

So to my question. I've been amazed in the past that what I thought was a really good soaking only went a few millimetres into the ground. So how much water should I give? Is 5 minutes with a hose per area enough?

Also, I got a water meter thingy a while ago, so now I can see if it rained 1 mm or 10, but actually I'm still none the wiser. How much rain is enough so that I don't need to water?

Thanks for any advice!


  • EsspeeEsspee Posts: 274
    I have no idea where this "received wisdom" comes from but I work on the idea that for pots, one inch of water goes down 10 inches.  Have to agree with you that flower beds, which you think have been thoroughly soaked are often dry just under the surface.  One tip I happily pass on is that a couple of drops of washing up liquid added to a watering can works as a wetting agent and allows dried up compost to absorb water.  Try it with two similar dried up pots. Give one a tumbler full of water, the same with a touch of washing up liquid for the other and measure the run off.  Plain water drains through but with the washing up liquid much more is absorbed.
  • KT53KT53 GloucestershirePosts: 7,531
    With pots you'll often find that very little water gets to the compost from rainfall because the foliage of the plants deflects most of it away.  For borders many established plants will cope with all but the longest and warmest periods of good weather that we get in this country, without assistance.  Plants that I have seen struggle are Astilbes and Anemones.
    I just do a wander around the garden and if anything is looking stressed I'll water it with a can.
    How long it will take to really soak an area with a hose is difficult to answer, but when I had a newly planted garden I used a sprinkler and moved it to a new section about every 15 minutes.  I also made sure to water late in the evening to get minimum evaporation.
  • paul_in_surreypaul_in_surrey Posts: 239
    edited May 2018
    It's been really tough going at the allotment over the last month. The 2 things I've been trying are firstly to only water around the base of the plants selectively, i.e. rather than just spraying everything I ignore herbs originating from the Mediterranean, etc. Second is that I'm trying to use the method that Carole showed on Beechgrove, which is to dig in an empty plant pot next to plants (particularly those susceptible to stem rot like cucumber and squash) and fill up the pot with water so it goes straight down to the roots of the plant rather than hanging around on the surface. Depends how big your beds are of course, but it may help with using an awful lot of water that very little of which actually reaches the roots.

    I don't really worry about too much - there's nothing you can do if it rains straight after watering so no point worrying.

    “Success is the ability to go from one failure to another with no loss of enthusiasm.” Winston Churchill
  • FireFire North LondonPosts: 17,116
    It's a good question.
  • FireFire North LondonPosts: 17,116
    "One inch of water goes down 10 inches."

    Esspee, in my experience, it seems more like ten inches of water goes down one inch of soil.

  • Busy-LizzieBusy-Lizzie Posts: 20,397
    I live in Dordogne so it can be hot in summer. I water each area for 30 - 40 minutes with a sprinkler, once a week if it hasn’t rained and 20 minutes for the bits such as the veg garden that have a leaky hose. I water pots every other day, a large watering can full. But I would think that in England it would be a lot less. A good soak from time to time is much better than a light sprinkle every day.
    Dordogne and Norfolk
  • wild edgeswild edges The north west of south east WalesPosts: 8,852
    Do you use trays under the pots? I have them under most of mine so water flows through and then gets sucked back up as the soil picks up the moisture. Otherise the soil doesn't have time to get fully saturated before the water starts draining out the bottom. Great with the rubbish compost we seem to get these days. I find it helps to conserve water in dry periods but obviously when it rains you have to remove them from some plants all to stop plants drowning which can be a bit of a faff. A shallow tray coupled with a good layer of crocks in the bottom of pots is normally enough to lift the soil just above any standing water though.

    For plants in veg beds I like to use a bit of pipe stuck in the ground next to the plant so you don't get the surface of the soil wet. This helps keep weeds down as well as reducing evaporation.
    Tradition is just peer pressure from dead people
  • Allotment BoyAllotment Boy North London Posts: 5,826
    edited May 2018
    @KT53 is right it is easy to think that rain is enough but pots rarely get enough for the reason stated. If you mulch beds after a good soaking you will not have to water as much in future. I also agree that a good soak once or twice a week is better than a little every day. Established plants draw water from quite deep down by capillary action through the soil to replace what is drawn up through roots so it is important not to have soil too loose, hence the apparently contradictory advice in books, of firm, "well drained but moisture retentive soil".
    AB Still learning

  • hogweedhogweed Central ScotlandPosts: 4,053
    I don't normally water established beds (but I do live in Scotland!) although this year with a lot of new plants and this unbelievably dry spell I have done so. Sprinkler on for around 45 minutes per bed. Pots which are fairly large are watered every second night often in the dark! 
    'Optimism is the faith that leads to achievement' - Helen Keller
  • wild edgeswild edges The north west of south east WalesPosts: 8,852
    Sometimes I like to do a quick water of the pots before it rains because if the soil surface is too dry it doesn't seem take up water as well or the water runs straight off. Gravel mulches reduce the need to do this though.
    Tradition is just peer pressure from dead people
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