Bulbs for the Southwest
Every year glossy catalogs full of gorgeous flowers entice gardeners to try growing bulbs that aren't suited to their climate. Many tulips, for example, won't come come back and bloom a second year. They just can't take the heat. Most fall bulbs come from Holland where the weather is cool and cloudy. Here in Arizona, highs in the 90's and sunny days are the norm from March on.
There is hope, however. Many bulbs come from warm climates, and others can be planted in a cool, protected microclimate. Here are some suggestions for our area.
Tip #1 Plant in Shade
All of those "full sun" recommendations are made for gardeners who get half the sunshine we do. Shade makes it possible for bulbs to flourish despite our hot climate, and helps their flowers last longer. Afternoon shade and shade from trees is especially helpful. As a general rule, the colder the climate where the bulbs come from, the more shade they need. I like to plant tulips in full shade on the northern side of my house.
Tip #2 Don't Plant Too Deep
When I first started growing bulbs, I would remove 6 inches of soil, place the bulbs carefully at exact spacing, and put all the dirt back on top. This was exhausting work. I have since discovered that planting 1-3 inches deep is perfect for most bulbs. Recommendations to plant 6 inches deep are for areas where the soil freezes hard. The only reason to plant deeply here is to keep the bulbs from getting hot in the summer. Heat and moisture can cause bacterial rot and destroy the bulbs while they are dormant. Shade and a thick layer of mulch can keep your soil cool.
Tip #3 Choose the Right Variety
This can make all the difference. Quite a few bulbs come from South Africa, Iran, and other desert climates. The good news is that you aren't limited to spring blooming bulbs from Holland. Here are some suggestions, categorized by season:
It is hard to go wrong with Daffodils, but some varieties are more resilient than others. Multi-flowered types do especially well. I also recommend Species Tulip, which bloom and multiply year after year (unlike the wimpy hybrids). Dutch and Bearded Iris can be glorious in mid spring. Freesia bloom and smell heavenly in April. Allium, Grape Hyacinth, and Amaryllis are also good choices.
Tropical Bulbs such as Canna Lilies, Crinum, and Gloriosa Lilies grow well in our summers. Rain Lilies multiply quickly and bloom repeatedly during the hotter months. They are most likely to bloom when watered after a good dry spell.
Many bulbs have winter foliage and fall flowers. These include Lycoris, Nerine, Oxblood Lilies, and Saffron Crocus. Dahlias survive through the summer, but put on their best show when it cools down in the fall.
Paperwhites start blooming in late fall and go through early spring. It really just depends on when they get water. I start watering them 1-2 months before I want them to bloom. Crocus and mini Iris Reticulata bloom as early as January.
Some of these are specialty bulbs that you can't buy at Wal-Mart, but they are readily available online. With the right planning you can have something blooming year round.