Watering plants in pots.

You can’t say it’s not topical.

I just potted on some of my tomatoes from 10 litre pots into 20’s. I should probably have done all of them, but I thought if I did alternate plants, then stopped the ones in the smaller pots while letting the others grow on, it should even itself out.

Tomatoes-2

I have been watering them twice a day for the last week or two, the combination of rapid growth and drying weather making it an absolute necessity. They’re looking a bit stressed, as am I.

It set me thinking about what advice I would give to a beginner about watering plants in pots. It might go something like this.

1) Try and anticipate how much growth a plant will make and aim to get it into a big enough pot to need watering no more than once a day.

2) Bear in mind that different composts will hold different amounts of water when saturated.

3) Water when a plant is dry and before it starts to wilt. Do not wait for evening, or any other time.

4) Ideally you want to apply enough water to bring the compost to field capacity (holding as much as it can against gravity) and not a drop more, run-off being wasted water as well as carrying away soluble nutrients. It’s impossible, get as close as you can. Don’t apply less; if you repeatedly give small amounts the roots lower in the pot will dry out and die.

5) Whatever amount of liquid feed you include in your watering will be better parcelled out into small amounts with every watering. Plants in pots will need more feed than the same plant in the ground; having a much smaller root system.

6) Dry compost is very hard to wet and often shrinks so that water runs down the sides of the rootball and out of the bottom. It helps to have the top of the compost dead level and it may be possible to wet the rootball by applying small amounts of water and repeating several times as soon as it has been absorbed. If that doesn’t work, stand the pot in water overnight, preferably submerged in a bucket. Next time don’t let it get that dry in the first place.

7) When planting out into the ground the plant will need much the same amount of water until its roots get out into the surrounding soil, a bit less because the root ball is surrounded by moist soil and a lot less after a few weeks.

8) Putting a potted plant into shade will reduce the amount of water it needs a great deal.

9) Don’t be complacent about watering, it is easily the most important part of looking after a plant in a pot. Pay attention while you’re doing it, it’s an opportunity to give every plant a quick check over. If you’re bored rigid because you’re spending hours every day watering you probably need an irrigation system.

9 thoughts on “Watering plants in pots.

  1. You have a LOT of tomato plants Jim! Last year I had 12 in my conservatory and watering twice a day at times, plus the feeding. They are a lot of work, but oh, the taste of those tomatoes plucked straight from the vine! I probably didn’t plant mine in big enough pots, but they seemed to do OK. I did make the mistake of planting out some small primula in to the garden and not watering them (my soil is quite moist, so I figured they’d be fine) only to discover that the root ball has dried out and not grown out into the soil as I expected! Lesson learned. Water new plants until established…

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    1. 13 tomatoes, you pay a lot for F1 seed and don’t want to chuck any out. Then I got everything right that I got wrong last year, timely start, good compost, right feeding regime, much improved light having cut down shading shrubs, then this heatwave. It’s still only June, they’ve a lot more growing to do if I let them. And we’ll eat every one.

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      1. I made a lot of tomato sauce last year and even gave some to the neighbours as I was away for a month (most untimely). I also grew loads of basil and chillies too – still got some of those in the freezer!

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  2. Fab post, Jim. I would like to invent a ‘worm-holer’- something to make channels through a pot so that the water gets to the rootball. My finger only pokes so far.

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  3. Jim do you ever mulch your pots?

    Here in WA the summers are revolting and on a trip to a good local nursery I noticed they had mulched all of the pots. They used a lupin mulch with pig manure called ‘piggy post’. The plants looked much happier than mine… So ever since I’ve copied them. Does anyone else do that?

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    1. I seem to have missed your comment, sorry. I don’t mulch my pots; I don’t believe it would be advantageous unless it contained something that was missing from the compost, like feed. If you want greater water holding, fill the pot with compost. It’s sometimes done by nurseries here to supress weeds and liverwort on the surface.

      Liked by 1 person

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