[Arid_gardener] Problems with Raised Bed Garden

Mon Jul 24 09:19:05 MST 2006

Hi Gaylene --

There are so many factors involved in creating and maintaining a successful raised bed garden in the Phoenix area that we may not be able to diagnose your problem(s) successfully over e-mail. The good news is that it is ABSOLUTELY possible to grow great vegetables, flowers and herbs almost year-round here in raised beds. I currently maintain eight raised beds (20 ft long x 4 ft wide) in my backyard garden, and am in the process of installing two more. Here are a few comments, based on my experience.

First of all, I highly recommend that you acquire a copy of "Desert Gardening for Beginners" (C. Cromell, et al), written by Maricopa County Master Gardeners specifically for this area. It contains a lot of great information on soil preparation and planting calendars, which I believe are two of the most important components of growing a successful raised bed garden here. There is also a whole section on Raised Bed Gardening in the book. For information on how to buy this book, check out http://cals.arizona.edu/maricopa/garden/html/pubs/mgpress/source.htm. 

Second, there is a wonderful demonstration garden that is maintained by Maricopa County Master Gardeners at the Cooperative Extension Office (4341 E. Broadway Rd in Phoenix). This garden includes quite a few raised bed vegetable plots. The garden is located just off of the parking lot, is open year-round, and admission is free (self-guided tour). Tour this garden every couple of weeks or months to see what the Master Gardeners are planting, harvesting, etc. If a Master Gardener is working in the garden, they will be more than happy to answer your questions.

Third, for more good information on low desert gardening, the Maricopa County Master Gardeners' Desert Garden Institute is offering an "Edible Landscapes" class on Sept 23rd from 9:00 to noon ($20) at the Maricopa County Cooperative Extension Office, 4341 E. Broadway Rd. The Master Gardener who is teaching the class, Pam Perry, is extremely knowledgeable! She is also Director of the Demonstration Garden I referred to earlier, and usually takes students on a tour of the garden after class. For more information or to sign up for the class, contact the MCCE Office at (602) 470-8086.

In my vegetable and herb gardens, I have found that three things are REALLY IMPORTANT for success here:

SOIL is key. "Desert Gardening for Beginners" describes a fast and simple method for testing your backyard soil, and then goes through the process of amending your soil to prepare it for a garden. Many newcomers to the Valley make the mistake of throwing out their current soil and installing planting mix in their raised beds. Actually, our soil is quite good, and supported a huge agricultural industry (cotton, citrus and alfalfa) here for many years. That said, the soil is generally quite nitrogen-poor and sometimes lacks drainage capability. "Desert Gardening for Beginners" does a great job of describing how to amend your soil, including adding lots of organic matter and the correct fertilizers throughout the growing process. From your description of your beans, it sounds like you may have over-fertilized with a nitrogen-based fertilizer. Nitrogen is the first of the three numbers on the fertilizer bag (for example, Blood Meal is 14-0-0, Amonium Nitrate is 33-0-0). Nitrogen encourages green, lush foliage. Once the plant starts producing flowers/fruit, you need to switch to a product with high phosphorus content, the second of the three numbers (for example, Amonium Phosphate is 16-20-0). Phosphorus promotes root growth and production of flowers and fruit.

TIMING is key, meaning that when you plant here REALLY MATTERS. Once again, "Desert Gardening for Beginners" is a great resource. There are three tables in the Appendices with Planting Calendars for Fruits & Vegetables, Herbs and Flowers. It sounds like you may have planted the beans too late, as most varieties have trouble pollinating after temps reach 90-100 degrees. Another great online resource is U of A Publication AZ 1005 "Vegetable Planting Calendar for Maricopa County" located at http://cals.arizona.edu/pubs/garden/az1005.pdf.

VARIETY is key, meaning that some vegetable varieties absolutely thrive here and many just don't. One key is to look for a low number of "days to harvest" on the seed packet, as we have several short growing seasons here in the Valley. I have found that the best way to get information on good varieties to plant is by touring local gardens (the Desert Botanical Garden also usually has a good vegetable and herb garden, but I believe it is still under renovation right now) and by word of mouth. It seems like every time I meet up with a Master Gardener, we are trading info on which varieties did well/poorly in our gardens this season. Another great resource is your local gardening club, or you can write in to this help line for advice on varieties to plant. Contact information for some of the local gardening clubs is located at http://cals.arizona.edu/maricopa/garden/html/clubs/clubs.htm.

The low production on your zucchini probably means that the bees weren't pollinating the flowers for you. Zucchinis produce both male and female flowers (the female flowers are the ones with the tiny zucchini at the base of the flower). If the bees are not pollinating the female flowers, the flower will brown and fall off and the tiny little zucchini at the base will shrivel and die. Since the bees are not doing the pollinating for you, you can do it yourself. Take one of the male flowers (the ones without the little zucchini at the base) and peel off the petals. Use this flower like a paintbrush to brush pollen into the female flowers. If you do this every couple of days (morning is best) on the newly opened female flowers, you should start getting squash. It is pretty late in the season, so you may have to try this next season.

Hope this helps! Good luck, and don't give up!

Carolyn Hills
Maricopa County Master Gardener Volunteer
  ----- Original Message ----- 
  From: glarsonaz at cox.net 
  To: arid_gardener at Ag.arizona.edu 
  Sent: Sunday, July 23, 2006 11:46 PM
  Subject: [Arid_gardener] Question from Home-Hort WWW page

  Gaylene
  85224
  glarsonaz at cox.net

  My husband recently built me raised beds for my vegetable and flower gardens. They are made of block with tar inside. They are 4 ft. wide and 2 1/2 feet tall. My summer garden this year was weird. Beautiful thick pole beans with no beans! Also bush beans with no beans and zucchini, one plant extremely bitter, the other very few zucchinis! They are on drip lines. Any ideas why so little harvest? Three varieties of tomatoes did great (except for splitting). Do you know where I can get my soil tested? And do you offer any classes on vegetable gardening? Thank you very much.

  _______________________________________________
  Arid_gardener mailing list
  Arid_gardener at CALS.arizona.edu
  http://CALS.arizona.edu/mailman2/listinfo/arid_gardener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://CALS.arizona.edu/pipermail/arid_gardener/attachments/20060724/f25b9025/attachment-0001.html