Keeping outdoor potted plants watered

ThisIsWeird

when not at home.
This is for someone who has a few potted plants on his roof terrace, and is often away for around a couple of weeks - they miraculously survived the last hot spell, but initially appeared quite dead when he returned.
I recall there used to be moisture-holding granules you could get - they'd swell and hold water in wet times, and release it slowly when dry? Do they work? Any other 'passive' systems and ideas?
Thanks.

Section62

ThisIsWeird said:

when not at home.

This is for someone who has a few potted plants on his roof terrace, and is often away for around a couple of weeks - they miraculously survived the last hot spell, but initially appeared quite dead when he returned.

I recall there used to be moisture-holding granules you could get - they'd swell and hold water in wet times, and release it slowly when dry? Do they work? Any other 'passive' systems and ideas?

Thanks.

For plants in pots with holes in the bottom I stand them in a growbag tray and fill the tray brimfull with water before going away.  Unless it is ultra-hot and I'm away a very long time there is usually still some water in the tray when I get back.  If it is an option then temporarily diverting a downpipe so some of the rainwater (if any) goes into the tray also helps.  Wilko have often been the cheapest place to get them, but as a seasonal item they don't always stock them.   https://www.wilko.com/en-uk/wilko-grow-bag-tray/p/0425572

Otherwise I set up a micro drip irrigation system using an old cold water tank as the water supply.  I'm not keen on leaving the mains water on, but that would be another option for the brave.  Just setting the drippers to the very least amount of 'drip' should be enough to keep the compost/soil moist.

stuart45

You can get self watering pots and planters. 
Has he asked you to go in every day to water them.😉

ThisIsWeird

Section62 said:

ThisIsWeird said:

when not at home.

This is for someone who has a few potted plants on his roof terrace, and is often away for around a couple of weeks - they miraculously survived the last hot spell, but initially appeared quite dead when he returned.

I recall there used to be moisture-holding granules you could get - they'd swell and hold water in wet times, and release it slowly when dry? Do they work? Any other 'passive' systems and ideas?

Thanks.

For plants in pots with holes in the bottom I stand them in a growbag tray and fill the tray brimfull with water before going away.  Unless it is ultra-hot and I'm away a very long time there is usually still some water in the tray when I get back.  If it is an option then temporarily diverting a downpipe so some of the rainwater (if any) goes into the tray also helps.  Wilko have often been the cheapest place to get them, but as a seasonal item they don't always stock them.   https://www.wilko.com/en-uk/wilko-grow-bag-tray/p/0425572

Otherwise I set up a micro drip irrigation system using an old cold water tank as the water supply.  I'm not keen on leaving the mains water on, but that would be another option for the brave.  Just setting the drippers to the very least amount of 'drip' should be enough to keep the compost/soil moist.

Thanks.

Cool - a simple as that? I'd have thought it would all evaporate in a few days during the last hot and dry spell? But I guess if it lasts even one week, the plant should be fine with its surrounding soil having been kept damp.

A micro-drip will be beyond him :-)

ThisIsWeird

stuart45 said:

You can get self watering pots and planters. 
Has he asked you to go in every day to water them.😉

I'll look into that. So, these 'gel' things I recall aren't an option? Seems the simplest idea.

(No, I won't be popping in - 200 miles away, and 6 floors up...)

Section62

ThisIsWeird said:

Section62 said:

Thanks.

Cool - a simple as that? I'd have thought it would all evaporate in a few days during the last hot and dry spell? But I guess if it lasts even one week, the plant should be fine with its surrounding soil having been kept damp.

A micro-drip will be beyond him :-)

Yup, unless the plants are really sensitive then the aim isn't necessarily to keep them 'watered' every day until you get back, but just delaying the point where the compost/soil dries out.  Equally, some plants can't stand being in saturated soil so may not survive being stood in a tray full of water.

Evaporation from the tray can be slowed if it is given it some shade, but if it is brimful to start with then it should take an unexpectedly long time for all the water to evaporate.  If there's only a few plants then put the pots towards the sunny side so the pots/plants help shade the unused space in the tray.

ThisIsWeird

Section62 said:

ThisIsWeird said:

Section62 said:

Thanks.

Cool - a simple as that? I'd have thought it would all evaporate in a few days during the last hot and dry spell? But I guess if it lasts even one week, the plant should be fine with its surrounding soil having been kept damp.

A micro-drip will be beyond him :-)

Yup, unless the plants are really sensitive then the aim isn't necessarily to keep them 'watered' every day until you get back, but just delaying the point where the compost/soil dries out.  Equally, some plants can't stand being in saturated soil so may not survive being stood in a tray full of water.

Evaporation from the tray can be slowed if it is given it some shade, but if it is brimful to start with then it should take an unexpectedly long time for all the water to evaporate.  If there's only a few plants then put the pots towards the sunny side so the pots/plants help shade the unused space in the tray.

Thanks. I think that solution is within his abilities :-)

p00hsticks

ThisIsWeird said:

stuart45 said:

You can get self watering pots and planters. 
Has he asked you to go in every day to water them.😉

I'll look into that. So, these 'gel' things I recall aren't an option? Seems the simplest idea.

The 'gel things you recall' do indeed exist and work as you describe, but they need to be mixed in with the compost when you actually first pot the plants, so aren't suitable in the situation you describe.

Miracle-Gro Water Gel Retaining Crystals Plant Pots & Baskets 200g on OnBuy 

fatbelly

Poundland used to do a water absorbent gel - seasonally, so probably in stock now. I think its usefulness is a bit limited. I used to mix in with compost along with slow release fertilizer (also from Poundland) but now I just get good quality compost and use that.

When I go away, I just move plants in pots to a shady location and give them a good water. I don't like to leave anything in standing water unless it's a bog plant

When I have tomatoes on the go, I rig up a system under a slowly dripping shower head on to a sort of capillary mat and stand them on that. When I come back they've rooted into the mat!

Emmia

p00hsticks said:

ThisIsWeird said:

stuart45 said:

You can get self watering pots and planters. 
Has he asked you to go in every day to water them.😉

I'll look into that. So, these 'gel' things I recall aren't an option? Seems the simplest idea.

The 'gel things you recall' do indeed exist and work as you describe, but they need to be mixed in with the compost when you actually first pot the plants, so aren't suitable in the situation you describe.

Miracle-Gro Water Gel Retaining Crystals Plant Pots & Baskets 200g on OnBuy 

I tried the gel, the summer we first moved in to the current spot, and I found they just made the soil/compost in the pots quite lumpy and gross, and I've not used it again. These days I tend to plant my plants in a mix of coir compost with perlite and vermiculite - the vermiculite definitely helps with water retention, but not in a way that the roots get soggy. 

We've only got a patio, so all the plants are in pots, and I tend to use planters with inbuilt water reservoirs - I've got Artstone planters, and Elho Greenville's 

https://hortology.co.uk/collections/artstone-planters/products/bola-artstone-plant-pot-black 

https://www.elho.com/en/products/greenville-round/greenville-round-30cm-living-black/

The Elho pots come in a wider range of sizes and colours (mine are all black!) and they do other shapes with the same feature. The advantage of these is you can water either into the built in saucer, or into the top - and if there is too much water it will overflow so the plants don't get waterlogged, it is also possible to see if there is water in the saucer to work out if you need to top them up. 

The Artstone's are quite attractive, but are more difficult to monitor in terms of water levels, I end up having to pick them up to work out if there is any water in the reservoir, if the pot feels light, then it is time to give it a soaking!

twopenny

Guessing we're going MSE so a drip system is out.

One thing I've seen is a pop bottle filled with water and turned upside down in the soil. If you can squidge it down into the pot aa bit thats good.
I use cut plastic plumbing pipe cut into lengths, holes drilled from half way down and the pipe set into the compost so just an inch is showing above. You water into the pipe and it disperses near the bottom of the pot. Water there doesn't evaporate so quickly.

Pebbles or grit on top will slow evaporation.
Moving pots to the shade.
If they aren't huge, a large container of water, dip them in and wait for all bubbles to disperse. That means the soil is saturated and no air round the roots. This is the best method I've found but it's heavy work.