Container Vegetable Gardening in Hot / Desert Climate

saoodhashimSeptember 30, 2013

Hi All

The reason why I am on Arizona forum is because I felt Arizona's climate was similar to the climate I live in. I live in Saudi Arabia - in Al Khobar. I compared the weather chart - monthly averages - of Phoenix to that of Al Khobar and found that on an average monthly Phoenix's temperature is like 5-10F lesser than the average monthly temperatures that we have over here. This pattern hold on for all the 12 months. So I thought here would be all the people who I can learn from.

I am a beginning gardener. Never done any sort of gardening before. I dont have any garden space but I do have a roof where I get 8 hours of sunlight in summer and 7 hours during other times. I receive sunlight from sunrise to around 2 pm. after which the area gets shaded because of a tall building just besides my apartment.

I have read a lot of books and am aware of quite a number of things like containers, pot sizes, soils, fertilizers, etc. etc. But thats about it. No practical experience. Further the internet and the books that I have read are more catered towards USDA zone 3-8 and the severe weather zones are rarely touched upon, if at all. As an example, I felt watering and fertilization needs in those zones are titled towards being conscious of over watering and over fertlizing whereas in hot climates like ours, our concern would be under watering and under fertlization.

My preferences are tomatoes, peppers, cucumbers, carrots, potatoes, garlic, ginger, corriander, mint. I would also want straw berries, if possible.

Tempratures are falling now a days gradually. The highest tempratures are 100-102F during between 12pm-1am and the lowest goes to 70-75F. gradually this is going to reach to 65-70F high and 45-50F lows in January. After which it will begin to climb back and reach the current levels back in End April/Early May.

Also one major problem over here is that I have limited options for potting soil and fertilizers as the local market is not developed enough to have all the stuff that is readily available in the US. A few local brands of potting soil and fertilizers. The local nursery guys are also not so well educated enough to guide any vegetable container gardener. They may know something about house plants and a bit about outdoor gardening but not much (infact anything) about container vegetable gardening.

Just wanted to get some help in this respect. Would highly appreciate any guidance.



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You would probably be USDA Zone 10b. Much like Yuma, Arizona.

My concern with using roof tops would be if the roof can support the weight. Container or raised beds on the roof can get very heavy once watered (or after a rain). To a lesser extent the water runoff can damage a roof if it sits under the container, so plan accordingly. You can also hang containers off of the eaves.

The roof can also get quite hot. You may need to put atop some insulative material or slight elevation.

That said the biggest difficulty arises in the summer. Otherwise you have year round gardening. In summer you want deeper soil (12-18 inches) to both hold moisture and add thermal mass. You want to plant at least 6 inches away from the container sides as they will get quite hot.

Painting containers white or wrapping the outside with aluminum foil can help keep cool. Providing both western shade and overhead shade can help (50-70% transmission block). But, you don't need western shade since that building gives it to you from 2PM onward. The 8 hours of light that you do get is plenty.

You will want to start a compost pile now (if possible) to replenish nutrients along the way. You will want your garden soil to have a decent amount of organic material (a good finished compost) to retain water. Apply heavy 4 inch thick organic mulch after your seedlings/plants start to come up.

Planting local varieties of vegetables usually works best. If you want to experiment, try seeds with germination to harvest dates of 75 days or less. Some annuals will actually survive and keep productive for 2-3 seasons.

As far as strawberries goes, I doubt you can grow them there. If you can it will be limited to the few cultivars developed in Univ of California-Riverside for the Imperial Valley area, I suspect. You quite possibly can grow alpine strawberries there though. They do well in zone 10 and in partial shade only needing about 4 hours of sunlight. It is also quite possible to grow them in window planter boxes inside the home.

Phoenix is a zone 9b/10a area so fairly comparable to there. There are a few vegetables and herbs that will do well in the summer. Best of luck.

Here is a link that might be useful: Desert Planting Calendar (Phoenix)

This post was edited by Fascist_Nation on Mon, Sep 30, 13 at 14:57

    Bookmark   September 30, 2013 at 2:40PM
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Thanks for the very informative advices. Like I said, I never found such advices in the books catered towards USDA zone 4-8 and I will keep those in mind.

At the moment, I am not overly worried about the weight as I dont intend to do a lot of gardening on roof top. Since I am a starter, I would prefer to start small. This matter may take relevance once I am confident about my skills and then think about how to counter the weight factor.

I have installled 50% shades which I put on at around 11 am onward to avoid the scorching sun.

I actually started off with seeds inside my house and just today I can see some of them germintaing. I was not expecting them to germinate under 3 days. I am not very sure, how to proceed further. Just thinking of providing them with early morning sun for 1 and half hour and then giving them sun from inside my house on a western window for another one and a half hour. This I plan to do for 3 weeks by then the temperatures would have relaxed a but for the baby plants to be on the roof top for 24 hours. The problem for now is that I really dont know what to do with them for the remaining 21 hours. I dont have grow lights - so that is not an option. Can you please help me,

    Bookmark   September 30, 2013 at 3:03PM
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You don't need grow lights. Florescent lamps work almost as well...though the ideal is a grow light (red) and a cool (blue) florescence light side by side on the same ballast. Sounds like you have a green thumb. You can also grow on a east or south facing window sill or table next to the window provided it doesn't get too hot. But seeds usually want warmer than typical homes (assuming you have air conditioning) to germinate. May also want an initial clear plastic covering to hold moisture if florescent lamps...probably will get too hot if using sun exposure.

Here is a link that might be useful: windows sill starting

    Bookmark   September 30, 2013 at 5:51PM
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Thanks yet again.

For some reason I cannot open phoenixpermaulture website. The other two were interesting ones.

1/ Seedlings
As for the seedlings, today I took my seedlings on the roof top for the early morning sun for 1 hour and put them inside a plastic sheet (not so clear though - will get a clear one). The temperature then was not more than 75 when I moved them back inside. Right now I have put them on my eastern window - which fortunately or unfortunately does not receive any direct sunlight. Light is fair enough however. Enough to be able to read and write easily.

Is the above schedule going to be ok for approx. 3 weeks? What else can I do? or am I doing extra? For how much time the seedlings should be in the dark every day?

2/ Plants
I also had bought two small plants (approx 6 inches) - 2 tomatoes and 1 pepper (dont know which variety) and they have been under my care for approx. 2 weeks now. I transplanted them in bigger pots of 14" and 10" respectively. Depending on the temperature and the heat of the sun, I place the plants under 50% shade (my wife helps me as I am usually out for work :) ). This may start from 10 am if it gets to around 90F by that time.

While the pepper is going good, I am not particularly happy with the tomato plants, as they seem to be showing signs of yellow leaves - Am I over watering them? Its almost 48 hours since I have not watered them as I can feel moisture beneath 2 inches of soil. While this tells me not to water, but my heart tells me to water them. Today I just did not listened to my heart. I hope this should not be too much stress for the plants :)

Previously I use to water at least once a day. But then the pepper plant has not shown any yellow leaves as yet. I haven't fertlized them as yet - I believe the potting soil is fertlized enough to last for a month (that's what the nursery guy told me).

To be very frank with you - I am still not able to understand the delicate balance between under and over watering. I was advised to be titled towards under watering when in doubt - but in this heat, should we do that? Probably, by putting the shades, I am bring the heat down and thereby the soil moisture is not evaporating as it would otherwise do.

3/ While I do put the plants under 50% shade (and sometimes double 50% shade - I did these a week back when the temperatures used to go upto 105). I am just thinking whether light through the 50% shade, is it enough for both the tomatoes and pepper sun loving plants to fruit later? When they say 6-8 hours of direct sunlight for tomatoes and pepper, does that mean direct unobstructed sunlight????

4/ As for fertilization, I dont have quite a lot of option - either those NPK pellets or composted cow manure. The nursery guy tells me to sprinkle composted cow manure (his preference) over the soil once every month - but I am not quite sure about his ability / experience with container vegetables. What would you advise? How about composted cow manure tea as part of each watering or some other periodical watering?

5/ The potting soil that I use does drain but then how to measure its drainage effectiveness. What is the yardstick to measure it. When I water it for 30 seconds continuously, it starts to drain from the bottom holes but not like running water - just drop by drop - each of the 6-8 holes start dripping. Now this drop by drop could go on for an hour or two. The dripping speed may be high to start with but slows down as time passes. Does this mean the soil is good enough? Isn't that excess water sitting there for 2 hours inside the container harmful for the roots. Did that cause the signs of over watering / yellowing of leaves to appear on the tomato leaves?

6/ Unfortunately, at the moment, in my apartment there is no provision for florescent lights. I was however, thinking of putting four 20W CFL bulbs - two warm and two cool. How far should they be from the top of the seedlings? Is 80W going to be enough? How long the seedling should be sitting in light? And can the CFL be installed top down (standing upside down) rather than left right (laying)?

Sorry for asking you so many question in just one post. I hope you don't mind that.

Your much appreciate help awaited.

Thanks and best regards


This post was edited by saood on Tue, Oct 1, 13 at 6:37

    Bookmark   October 1, 2013 at 2:03AM
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Dear Saood,

Though I cannot answer all your questions I believe I can help a little. I live in Arizona and have found three very simple things we do here to ensure that our vegetables grow well through the summer .

1. Plant vegetables that tolerate the heat very well such as cucumber-melons like carosello, sweet potato and hardy pole beans,

2. I plant my vegetables far from sources of radiant heat such as block walls and houses where the heat will collect over the day and emit heat at night and

3. Water once every 2-3 days for a longer period of time. Though it is very counter-intuitive, the worst thing you can do in a very hot summer is keep the roots close to the top of the ground by watering each day. By watering less often at night for 2 hours with a soaker hose you allow the roots to grow deep into the ground where they can stay cool and moist.

If I am going to plant in a pot it needs to have a water reservoir under the pot and needs to be insulated on the sides. I occasionally grow pole beans over the west side of my plants - otherwise I never shade them.

Here is a link that might be useful: A few Tips for Growing Tomatoes in AZ

    Bookmark   January 22, 2014 at 4:17PM
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Hi Saood,
I know this is several months late but I only just saw your post. I moved to Mesa, AZ in late 2012 and started a container garden in my back yard in the spring of 2013 and I have grown most of the plants you mentioned you had an interest in. My backyard was very nicely landscaped by the previous owner but he put down a concrete patio that covers most of the backyard and so it tends to get from 4-8 degrees hotter than the surrounding areas - my backyard hit 120 F several times in June.
I started my container garden with a variety of herbs - basil, mint, parsley, thyme, sage, and oregano - and I used moisture control potting mix and self-watering pots and bought seedlings. Quite frankly, I don't think its possible to over-water basil - in fact you may need to water more than once a day when it gets really hot - 120F. Mint and parsley do best in partial shade (only a few hours of sun) but they will still look bad in the summer, even in the shade. I also had my thyme and oregano in partial shade as well in the summer (although not as much as the parsley and mint). My sage did really did well at the start and grew the fastest, but died in August. Not sure why since it did ok during the hottest time in June.
You mention coriander which is the seed form of Cilantro. Since I like Cilantro I started from seed in September and it was at its best in December and is now flowering and will become Coriander soon. However Cilantro will bolt (go to seed) quicker in hot weather and since you want Coriander if you start in late Spring it will go the seed quicker than if you started it now.
I also grew Eggplant and Pepper (8 kinds - 2 Bell Peppers, one banana pepper and 5 types of hot pepper). I had a lot of problems with the Peppers, especially the Bell Peppers, during the summer, and had to put then all in the shade for most of the day. Also I made the mistake of planting them in Moisture control soil in Self-watering planters - peppers don't like "Wet feet" so keeping their roots moist is a no-no. However they still survived the summer and produced quite well starting in October - although they never got to the size claimed - only about half of what was claimed but in very good quantity.
Eggplants did amazingly well and as long as they were kept watered (daily during the hottest days of summer) they kept producing and their leaves didn't even droop in 120F weather, while the peppers in the shade looked terrible. Size-wise the eggplants produced were also small but my 5 plants produced hundreds of fruits over the summer and fall - they only stopped producing when it got cold in December.
In terms of fertilizer, herbs and vegetables grown in containers require higher amounts of fertilizer - up to double. Peppers (and also tomatoes) require extra calcium as well (I used ground-up eggshells).
I also agree that underwatering is better than overwatering (I overwatered my pepper plants in the Spring and they didn't grow that well which exacerbated by problems with them in the summer. I also lost 2 peppers in the Spring due to overwatering. However as I said I don't think you can overwater Basil - they took the most water relative to their size than another plant and they can droop in the heat if they run out of water.
Container Size is also an important consideration. Most of the herbs were grown in 10-12" pots and that seemed fine. My Peppers were grown in 12 and 15" pots. I think the 12" pots were a little small but they still produced. The Eggplant was grown in 15 and 18" pots and the ones in the 18" pots grew really large. Container size also dictates the frequency of your watering regime as well. If the pot is undersized once the plant grows to its "adult" size, then you will need to water more frequently.
Anyway, good luck on your container garden. BTW, if you live next to a really tall building, do you live within a large city? Hopefully there is a source of bees or other pollinating insects? I used to live in NYC and they have beehives on the rooftops of some buildings.

    Bookmark   March 15, 2014 at 11:07PM
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