I volunteer for a large system of community gardens in Chicago– 664 plots at four sites. I see a lot of poor cultural practices when it comes to watering, so here’s some tips for proper watering, especially if you have raised beds:
How to tell when the plot needs water
The surface soil is not an indication—unless you have mulched (which is a good idea, more below), the top inch or two will always dry out in the absence of rain. Dig down about two knuckles deep. If the soil there is dark and even slightly damp, give it another 12 hours and check again. Soil should not stay muddy, wet, or so damp that it’s hard to dig through with your hand—this is too much water. If the soil is dry a full finger’s length down, it needs water.
How much water should I give it?
Rule of thumb is 1” per week (NOT 1” per day as a gardener suggested to me a few days ago). Based on a very unscientific watering test in my backyard, this seems to be about 8 to 12 gallons (4 to 6 watering cans full) for your 4x8ft bed. I would err on the side of too much water if you know there is no rain in the forecast. Rain counts—if you get an inch of rain, you don’t need to water. If you get a half inch, you don’t need to water as much. Watch the weather report.
Where should I water?
Water the base of the plant. But this does not mean “only the base of the plant.” It means “don’t water the leaves.” Water ALL of the soil, not just the area immediately around the plant. Remember that the roots are spread out throughout the soil. Watering in just one spot will encourage the roots to stay there, where the water is. Make the plant work a little to get a drink.
Why not water the leaves?
Especially on hot days, if there is water on the leaves it can actually burn your plant. Further, leaves get their water from the soil, relying only secondarily on the humidity in the air. Don’t be alarmed if your plants are droopy in the midday heat—they are conserving water where it counts—in their roots—and letting the extremities suffer a little. If you come back in the evening, they’ll be all perky again.
Seeds and seedlings
Seeds need to be moist, but not soaking. The problem is they are in that surface area that dries out. Once you water seeds, you have to keep that top couple of inches damp until they sprout. If you water them too much, however, they’ll just rot. If they germinate and then dry out, they’ll die. Be aware of how long it takes seeds to sprout—it’s different in different plants, so you can be aware of how to water. Water your seeds shallowly and your seedlings deeply.
Puddles
If you’re getting puddles when you water, either you’re watering too fast, or you’re watering too much. Watering cans deliver a lot of water in a short amount of time, not giving the soil time to absorb it, so it just pools on the surface. Water very slowly, and wait a few minutes between cans of water to allow it to seep into the soil. Use the spout cover; don’t remove it so that you can water faster. Especially on hot days, water sitting on the surface of your plot is just going to evaporate.
Should I water after a rain?
If it rains a full inch, you’re good for a week. Do the finger test a day or two after the rain, and keep in mind the weather. If it’s especially hot or windy, the soil will dry out faster.
Sprinklers
I confess. I water using sprinklers when it’s really dry like this. But I have a large garden (23×70 feet) and crazy curvy beds making a drip irrigation system nearly impossible. If you water with a sprinkler, do it in the early morning. When we’re getting adequate rain, I barely water my very mature garden at all because the plants themselves hold the moisture in the earth just fine. When I do water, I use cached rainwater, and yes, I carry the watering can back and forth. It’s good exercise.
Mulch
Yes. Nice mulches are: mushroom compost, cocoa shells (remember not to use cocoa shells where dogs, ducks or other precious critters might ingest it. I’m not so concerned about the squirrels and wild rabbits), leaf mold, “black forest mulch” (shredded leaves and wood). Do not use peat moss (water will run right off of peat moss, defeating the entire purpose, plus it’s not a renewable material), pebbles, bark, or wood chips. Once your plants are large, their own foliage becomes the mulch and helps to hold the moisture in the soil.
Best time to water
Water in the early morning or early evening (but not too late. You don’t want the sun to go down on wet foliage). If you water at the height of the midday heat, a lot of the moisture will simply evaporate and your plants won’t get the full benefit of what you’ve given them.
What are your best watering tips?
How does your watering advice differ for potted plants versus in-ground or raised bed gardening?
Thanks!
For potted plants, you want to water JUST before they start feeling the pain–don’t let them get droopy. You need to know your plants. When you water them, water until you get some dripping through the bottom of the pot, so you know you’re flushing out the minerals that build up in potted soil. (You’ll know you’re not watering enough if you get the white salty accumulation on the outsides of your pots)
Thanks; this is helpful.
But you should qualify the amount of watering when it’s very hot as in +100 degree days that we get a lot of in central Texas, heck, all of Texas. One inch per week and we’d never be able to harvest anything.
Exactly– there’s no hard and fast rule that will fit every situation. Even here in the upper Midwest I’m watering way more than I would normally feel comfortable doing, because the soil is so dry from the drought that I’m probably adding more than the “rule of thumb” 1 inch per week right now. Also, my soil is quite sandy, which means it drains quickly, so I need to water more for the same effect that someone with a loamy or clay soil will need, (let alone hardpan that you get in the desert sw)
That’s a very important observation. I have a sandy loam, and I find I have to add a lot of supplemental water. On the other hand, Mama has clay and fed a family over the years on a garden that was not irrigated.
A few years ago we installed a drip irrigation system in our vegetable garden. I’s a pretty simple system made by hand from PVC pipe and isn’t perfect but works pretty well. It keeps us from wasting water and gives the plants a deep soaking. Our garden has really thrived since we installed it and the best part is the amount of weeds in the garden is way down because they don’t get any water!!
I generally vote for drip systems as well, but have read a book recently that disparaged them. Thinking back, i’m actually not as big of a fan as i thought i was: the drips sends water pretty much just straight down unless you have REALLY nice soil, thus only watering in dots. Which is lame.
My biggest tip is use rain when possible. Rain barrels are cheap if you scrounge them and plants love rain so much better than oft-chemically treated ground/ city water.
I spread about a 3-5 inch thick layer of straw (not hay!) as mulch in my garden–it saves my sanity. It’s a great weed suppressor, plus keeps the moisture level of the soil even, and helps against water evaporation. Costs about 4 bucks a bale, so I count on spending about $25-30 per season. It breaks down nicely, too, adding more nutrients to my soil.
I love straw as mulch! This year I have had a lot of plants that seemed nutrient deficient in beds I mulched with straw last fall. It didn’t break down as much over the winter as usual, and may be tying up the nitrogen. It’s still great mulch, but something to be aware of…
I also use straw to fill up the bottoms of large pots- anything deeper than 10″. Cheaper than soil, and makes the pots much lighter.
I learned the difference between hay and straw the hard way– used hay because it was free from the local Hallowe’en parade. And now I get a nice little hay crop every year.
I’ve got a raised bed garden and I have always struggled with it to grow anything because I hate to water. So this year, my husband installed a soaker hose for me. It’s about 4 inches below the surface of the soil. I’ve got a heavy duty hose run to the bed so that all of the soaker is in my garden. I check it before watering by sticking my finger in the soil to see how it feels near the roots and this year my garden is doing so well. I’ve been trying to pay attention to rain and whether or not the soil feels dry before watering. Some weeks I haven’t watered at all because we’ve had rain. And I find I watered more in the beginning when I first planted but now that my plants have had some time to grow, I’m not feeling quite as compelled to water them. Thanks for the great tips.
I love things like the finger test to check for moisture. I’ve had people ask me about moisture sensors, some of which can be quite expensive, but I always think hands-in-the-dirt is the best test.
Actually, a full inch of water for a 4′x8′ bed is 2.67 cubic feet of water, or 20 gallons.
I also highly recommend getting a rain gauge for your garden, and using that to determine how much water you’ve gotten from a rainstorm. I live in upstate NY, and we get a LOT of scattered showers and thunderstorms, where one side of town will get an inch of rain, and the other side won’t get any.
When we haven’t gotten any rain, I usually give my garden half an inch of water (10 gallons per 4×8 raised bed, moved by hand in buckets from my pond) twice a week. That’s enough to give everything a good soaking each time.
In the summertime here, the weather forecast will say there’s a 30% chance of thunderstorms sometime in the next couple of days . . . which means that I might get an inch of rain, and I might get nothing. Watering in half inch increments every 3-4 days if we haven’t gotten a good rain prevents unnecessary work, while keeping the plants happy.
Well, gosh, if you’re going to go and use *math*…. (My test was very unscientific–I put a rain gauge in a plot and watered back and forth with a watering can until it showed an inch, which was 8 2-gallon cans, or 16 gallons. So I wasn’t too far off, come to think of it).
I did the math because I wanted to make sure I was using enough water, and I fail at watering evenly . . . it’s actually not that bad. To figure out the number of cubic feet of water you need to get one inch for the bed: (1 inch in feet) * (width of bed) * (length of bed) = 0.083 * 4 * 8 = 2.67 cubic feet
Then entering “2.67 cubic feet in gallons” in Google search tells me that I need 20 gallons of water.
One thing I will say as advice, which people always forget is to moisten the soil BEFORE you plant the seeds. Great post though…!
And of course the reason that I left it out is that I always forget to do this. I was extremely proud of myself the other day when I was showing some kids how to plant and actually remembered for once.
Try clay pot irrigation. It is ancient technology. Search clay pot irrigation, olla irrigation, pitcher irrigation. I have used it a few years now in Central Texas and results are good.