How to Water Plants Correctly

, written by Bob Flowerdew gb flag

Watering sweet corn with a watering can

Plants are nearly all water, even wood is mostly water, with some carbon dioxide and a tiny amount of minerals. Water’s the pump that lifts sap with leaves evaporating it away so that more is drawn in by the roots. And water is the medium in which all internal processes take place. Thus providing ample water is a gardening priority.

Most temperate plants and especially garden crops grow most rapidly from spring thro’ summer and need about an inch of rain or its equivalent each and every week. Except in very rainy weather you can hardly over-water any plant growing in the ground. For almost all plants, especially vegetables, doing more watering will always give much better results; more flowers, lusher foliage, larger and sweeter crops. I find sweet corn, peas and beans, tomatoes and potatoes need most water from when their flowers appear and giving them even more from then on increases their yields tremendously. Others such as lettuces and most leafy salads really need continuously moist soil or they may become tough and bitter. So I now water much more than I used to and do so more often.

However few plants like water-logging and so we need to be much more careful with any growing in pots or containers. It’s easy to kill plants by standing their roots in wet compost or soil when they are not growing strongly as they drown. Roots need to take in oxygen and give off carbon dioxide and if standing in water they die rapidly. Unfortunately the plants then wilt and look as if they are short of water (which indeed the top growth really is), often resulting in even more watering and drowned roots becoming rotted beyond recovery. (Hydroponic culture has to make provision for root aeration, except for those water and bog plants which are especially adapted to such conditions.)

Different Watering for Different Plants

Roots in the ground can only be watered from above unless special irrigation pipes or funnels, tubes or similar are fitted which is well worthwhile. Usually most plants in the garden will have water supplied from a hose or pipe - don’t use a sprinkler if you can apply water to the soil directly not the plants. It’s better not to wet most plants as this can cause problems such as fungal diseases -and much will just evaporate away anyway. Water gently, with a rose (like a shower head) which will damage the soil less than a jet of water and prevent much mud splashing up onto the leaves. Also it’s better to wet the ground really heavily occasionally rather than to just splash a little about more often which can make the soil look damp on top while remaining dry underneath.

Watering young plants from below
Watering young plants from below

In pots though we have to be more careful - here roots are totally reliant on our watering and cannot seek out more on their own. We must water methodically and regularly. And we have a choice - whereas larger pots and containers with established plants can usually be watered from above with a rose on a can or pipe it is much better when sowing, pricking out and potting up small plants to water from underneath. I stand pots in saucers and fill, and then re-fill them as it’s sucked away. It’s important not to let pots stand in water for longer than a half hour or so before emptying any left in them or it could damage the roots. However this soaking upwards of water stops the top of the compost packing down so improving seedling emergence, and it prevents the other common problem of a wet surface remaining dry underneath. (If the compost ever gets totally dried out then submerge the pot for ten minutes in a deep bowl of warm ever so slightly soapy water, then drain thoroughly.)

As to the water itself, I use only (and preferably warm) tap water for sowing, small seedlings and delicate plants as many rots and wilts are caused by water from dirty rain barrels. We all must use only fresh clean tap water on salads and other crops eaten raw- for obvious reasons (see our article on Grey Water for details). Tap water is convenient and may be your only source of any quantity and will do for most plants. But in areas with hard water tap water will not suit acid lovers such as azaleas, blueberries and heathers. Rain water, held in clean rain barrels, is by far the best for almost all plants in the ground and even the more-so for those in pots as it has no chlorine or dissolved minerals which may build up in a pots’ compost. And when your plants are desperate even the dirtiest water from rain barrel, pond or ditch, and the grey water from your sink, shower or bath will have to do. But please do not use these on those salads….

By Bob Flowerdew.

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Comments

 
"Thanks for all the information. I just started vegetable gardening and I'm learning on the fly. Question...my husband put in a shallow well that I can water my garden with. Is this ok water for salads? Also, I planted asparagus early this year and then we had a big rainy week. The asparagus sat under water for a week and has yet to sprout...Do you think I killed them or should I wait until next year and see if they come up at all? Thanks, Donna R., CT"
Donna R. on Friday 3 June 2011
"Your article makes me feel like we are doing something right with the garden! This is our second year and we went bigger this time going from a 6 X 18 box garden to a 25 X 40' area. My husband set up PVC pipes along each row in three different sections, so we water 1/3 of the area at a time. It is almost like irrigating with the amount of water each row gets, however the area is sloped a bit so one corner (nothing is planted in that area) gets more water. I live in AZ so it is HOT. I am watering every morning for about 5-10 min for each section. The plants seem to be thriving. Am I over doing it? I sometimes wonder if I should do one morning and the next evening? Thank you for your thoughts! "
YB Ranch on Friday 3 June 2011
"Thank you for the concise, yet relatively comprehensive article! However, I was hoping to find more information on the ideal timing of watering, for vegetables specifically. I have a small veg patch in the south midlands, and given the lack of rain recently, am having to water regularly. I have heard that early morning and in the evening is ideal, but I am only watering in the morning at present, and with relatively young plants, don't want to damage them. Any advice will be gratefully received! Thanks Phil"
Phil Sheppard on Friday 3 June 2011
"@Phil, during hot weather I tend to just water in the evening as it then gives the plants plenty of time to absorb this without a lot of the water just evaporating in the heat @YB Ranch - it sounds like you are watering the right amount but again I think evening is better. When it's hot I water until it just begins to 'puddle' on the surface but once in a while it's worth checking that it gets absorbed lower down as very hot areas can get a crust of hard earth on top which doesn't let the water through. You might be interested in our article on Dryland Gardening here: http://www.growveg.com/growblogpost.aspx?id=88"
Jeremy Dore on Friday 3 June 2011
"@Donna, whether you can use that well water on salads depends on what runs into it. I would be cautious (see the Grey Water link in the article) and certainly not use it directly on the leaves unless you are sure it's a pure source. As for the asparagus, crowns are valuable so it's worth seeing if they'll come up next year."
Jeremy Dore on Friday 3 June 2011
"My garden is on a slope and has mostly heavy clay soil. I make a good bit of compost and continually add that to help amend the tilth of my garden soil. I generally water at night and find that the vegetable plants and berries seem to like it. Recently, I have been begun a vermiculture project and have also purchased a good amount of worm castings to the soil directly...WOW! What a difference it has made!!! Those little wigglers are miracle workers...and the more worms in the soil the easier it is for the water to saturate...all those little worms and their burrows make a huge difference. By the way,Bob, FLOWERDEW is the perfect name for a "GreenMan Gardener"!"
Denise in Virginia on Saturday 4 June 2011
"Sorry for all the typos in the above comment...my brain is just rousing itself from sleep hangover...obviously I need MORE COFFEE! LOL!"
Denise on Saturday 4 June 2011
"I have just extended some herbaceous borders adding lots of compost, thoroughly dug in. The borders are sorounded by dry stone walls and every morning I'm finding lots of 'tunnels', presuming these are made by rodents? When I come to water the plants I'm finding lots of air pockets which take soil and water away from the roots...frustrating. If this problem is caused by rodents, I don't really want to use poison, traps might be dangerous to others and I have a manic rescued lurcher so can't trust him with cats. We have filmed stoats from time to time, appearing and disappearing in/out of the walls. Any suggestions would be gratefully received."
Pat on Saturday 4 June 2011
"Just a short thank you note to Jeremy in particular, for a very prompt reply! Further, thank you all for an excellent site affording sterling service! Cheers Phil"
Phil Sheppard on Sunday 5 June 2011
"Pat, We use auto emergency flares in the bigger gopher, mole holes prior to planting the veg garden every year. I doesn't so much kill them as totally chases them away. Be careful not to do this around plants you want to save. As far as watering is concerned, we have a 40 ft. diameter Labryinth veg garden that last year was watered using a center sprinkler. Luckily, all loved it. We have very hot weather, so watering overhead in the am doesn't create fungus."
Kate on Monday 6 June 2011
"i was reading your blog in amateur gardening 19th may 2012.. in the article you said to make carbon dioxide you used a bottle of fruit juice,sugar fermenting with yeast.. whats the measurements to make this please "
sue butler on Monday 21 May 2012
"I have a snake plant, quite suckulent. I have a pathaus, quite suckulent too. How often do i water them, and how much? My snake plant has grown about 5 or 6 new babies. My pathaus is growing down on each side. Looks very nice. I had two or three wandering jews, but they died on me when winter time came, I dont know why, they were quite suckulent. Explain. "
Keith B. Sullivan on Tuesday 22 January 2013
"You may also be happy to know about DriWater www.driwater.com. It's a gel based product that makes sure plants stay watered when you are away from home or can't set up irrigation. But I liked your instructions and I'm pinning to our Pinterest account. Thanks!"
Kerry Rego on Sunday 19 May 2013
"Help....I have total sand and fire ants. I am in central Tx. I have a hard water well. For the seconded year my garden is terrible. Any advice???"
Bonnie Repp on Saturday 8 June 2013
"what alterative can you use instead of rain water,i have a carniorous house plant but i have run out of rain water,thanks"
stuart on Friday 17 April 2015
"Go green for save nature. save nature for our future."
Satpal Rolan on Friday 21 August 2015
"we just planted our potatoes and right after planting we got 1 in of rain will cause our potatoes to rut soil was fair dry"
cal bender on Sunday 21 May 2017
"Thank You For This Information"
Ponic Greens on Thursday 17 January 2019

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