Congrats on creating a little bit of heaven on your patio. Your problem could be the high salt content of water in arid climates. The brown edges of leaves is one symptom of too much salt. Try using a water filter to keep out salt. Too much fertilizer could also cause this so never use more fertilizer than the label recommends. Miracle-Gro is safe for potted plants as long as you don't overdo it. Not sure if you are watering too much or too little, but feel the soil and water when the top inch is dry. Begonais and columbines like cooler weather. Try to grow plants more adapted to your climate such as geraniums, sedums and succulents. See what does well in your neighborhood. Keep growing, Marianne Binetti