Drip irrigation concern
 

Hey all...

I have a concern, and I hope to find and answer for it here. I am growing tomatoes in 15 gallon containers, and have set up an automatic watering system, using 1/2 gph drippers.

Last year, my tomatoes did not do well, and I am wondering if it has to do with the fact that the drippers do not get the entire pot wet, and over the course of the season, probably erode a fast channel to the bottom of the pot, so that most of the soil never gets wet, and the roots don't grow... when I pulled up last year's plants, they had sad, underdeveloped roots.

Other than hand watering once a week, and really soaking the pots, what can I do?

Thanks,

E

Hello E,

This might sound like a silly question but when you pulled up the roots, did the soil/compost seem very dry?
I'm only asking because a couple of years ago I used a compost mix that retained too much water this also produced weak plants with small roots because I was effectively drowning the plants.

Having ruled out too much water. you could add amendments to your mix that retain more water such as more compost and/or manure.

You could also prevent water loss through evaporation, A layer of mulch on top of the mix will help to reduce this and you could set your system to water your plants at night when it's cooler.

Hope this helps

Kevin

Drip irrigation concern
 

You can make a ring out of the 1/4" poly and attach several emitters. Put the plant in the middle then with a T connector connect back to the mail line. That should help.

I had tomatoes in 7 gal fabric pots last summer with 1 dripper/bag and I didn't have any problem. It may be that they're staying too moist.

Another option is blumats. They're automatic water emitters that feel if the soil is drying out, and when it does they emit water until it is moistened. They work great, but if you've got lots of plants it could get pricey.


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Another problem with drip irrigation and pots is over-watering to the point you flush out a lot of the needed nutrients (leeching).

I have been putting seasoned wood in the bottom of my pots to retain some water. You just need to be careful as the wood will pull nitrogen the first year or two in the pots so bear that in mind and check for nitrogen deficiencies.
As kevin pointed out, The mix is important as well to help hold the water.

Monitor your pots when the irrigation is running to see if any is running out of the bottom, I had this problem with a few pots and needed to tweak by reducing emitters.
You will need to find the middle road... adding another emitter if you need more water, or if your pot is getting too much water, reduce watering time and add an emitter if needed, you can also get adjustable emitters.
for my big pots I have tried a loop of emitters (2-3 depending on the pot) using pressure compensating drip line.
I also put a valve on each pot and every section of the garden including a bunch of Hugelkultur beds, vertical towers and trellis, so I can turn off each individual area if needed.
It's just one of those thing that you have to find the sweet spot, balancing, time, emitters, soil etc...
I added another pot this year lined with wood and will have to monitor the watering and adjust if needed to be in sync with the rest of the garden... hope that makes sense?

For a pot that size your emitters are too small. I use 3.2GPH Netafim Spray stakes. You also want about 10 percent runoff, that will keep you from getting a build up of salts if you have a long growing season.

I agree that the drip emitters you were using were too small. If you're using 1/2 gph drippers, and had them on for 2 hours per day, that's only 1 gallon of water per day. That might not be enough during hot weather. If you were running the drippers for only 15-20 minutes, then definitely not enough.

I have my tomatoes in 7 gallon grow bags and I'm using 2 gph drippers. I have them on 15 minutes twice a day for now since we're having weather that is in the low 70's but I'll ramp it up once we get to serious summer weather.

[QUOTE=AKmark;695943]For a pot that size your emitters are too small. I use 3.2GPH Netafim Spray stakes. You also want about 10 percent runoff, that will keep you from getting a build up of salts if you have a long growing season.[/QUOTE]

How would he get a build up of salts from watering?

SW -

Ferts, if not the chems from city water. I make it a point to flush my points, but sometimes a pot of two will get a hard crust

[QUOTE=SQWIBB;695962]How would he get a build up of salts from watering?[/QUOTE]

This may help, take note of the salt index. I get my recommendations for runoff from Hydro Gardens growers manual.

[url]https://aggie-horticulture.tamu.edu/ornamental/greenhouse-management/managing-soluble-salts/[/url]

[QUOTE=mobiledynamics;695964]SW -

Ferts, if not the chems from city water. I make it a point to flush my points, but sometimes a pot of two will get a hard crust[/QUOTE]

Even more fast is the pH change of used fertilizer solution. Tomatoes can tolerate quite high salt index compared to other plants, but runoff pH changes can happen rapidly in fast growing conditions depending on the fertilizer content. Overhead watering when using chemical ferts is a must.

When my drip is on I run it several times in the morning and again in the heat of the evening.
Maybe a total of 4 to 6 times a day.
This is in raised beds that can drain.
Mineral build up has a lot to do with where the water comes from, river lake or well and what part of the country.
Here it is calcium another place I lived it was iron.
But the last place may have been from the old iron pipes too.:lol:

To get a good time customized automated drip system you really need a good controller not one of those battery operated faucet things.

I have used the fan type drip emitters that allow you to adjust the amount of water coming out too.

Here is what they look like.
Some people cuss them but I have never had a problem with them.
You just need a good fine mesh filter in the head end of the system.
These just run off a main 1/2 inch header along the path of the containers.
A 1/2 line can feed a ton of them.
For larger systems you can balance out the flow and pressure by tying back into the feed line at the end making a main feed line loop.


[IMG]https://images-na.ssl-images-amazon.com/images/I/51JO-5lcZbL.jpg[/IMG]

Drip System Aside ,what was the pot medium ?

[QUOTE=AKmark;695969]This may help, take note of the salt index. I get my recommendations for runoff from Hydro Gardens growers manual.

[URL]https://aggie-horticulture.tamu.edu/ornamental/greenhouse-management/managing-soluble-salts/[/URL][/QUOTE]


Interesting, I never thought of irrigation water building up salts in the soil...thanks...now I got something else to worry about:)

I used epsom salts on my plants a few years back and noticed the salts in the bottom of my grow bags on the outside, white staining in appearance and definitely salt.

[QUOTE=SQWIBB;696023]Interesting, I never thought of irrigation water building up salts in the soil...thanks...now I got something else to worry about:)

I used epsom salts on my plants a few years back and noticed the salts in the bottom of my grow bags on the outside, white staining in appearance and definitely salt.[/QUOTE]
Epsom Salt is magnesium sulphate, with a relatively low salt index (44).

Hey everyone!

Thank you for all the great info. After giving it some consideration, I switched to 1/2" supply lines feeding each 1/4" line. (previously it was all 1/4" since I was going for slow drip.)

I went with the sprinklers in Worth1's post, and I am delighted to say that now that they have enough pressure, I was able to fine tune each one so that it seems that it will water the entire pot, and, fingers crossed, promote good root growth.

It seemed like the easier solution, though setting up a ring of drippers as suggested by Texastomato, sqwib, and considered the emitters suggested by Akmark.

But I l ready owned Worth1's and started gave it a shot. If the lower branches have issues from being wet, then next season I'll switch to a ring small drippers.

Now I just have to figure out the gph, and fine tune how much to water.

Thanks again!