Geraniums are one of the most popular and best seasonal flowers for growing in pots on patios.
Although classified as a perennial, geraniums are usually grown as annuals to be enjoyed for several months in the spring and fall. They can be kept during the summer, but our intense desert heat usually renders plants weak and flowerless until the arrival of cooler weather in the fall.
Geraniums are best grown in containers. They flourish in direct sunlight from October to April but must be moved to shady locations when the sunlight in late spring and summer becomes too intense.
As geraniums are frost sensitive, they may also need protection during the winter months.
Finally, geraniums should be grown in pots to provide them the rich, acidic soil they prefer.
Most potting soils are fine for geraniums; however, regardless of the brand, I recommend mixing in a generous portion of perlite — one part perlite to four parts potting soil works best —to improve drainage.
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I also recommend a time-release flowering-plant fertilizer that has nitrogen, phosphorus and potassium and a number of micronutrients.
These beaded fertilizers break down slowly, releasing a steady supply of nutrients to stimulate continued growth and flowering.
March, when frost danger is past, is the ideal time to plant geraniums. Or plant in October before cold weather returns.
In the summer, geraniums do best in a shaded location with morning sun only. Regardless of the care you give them, however, summer will take its toll, and the plants likely will fade.
In the fall, cut these plants back to within a foot of the soil to stimulate new growth and flowering.
Geraniums are also easy to propagate from cuttings most anytime of the year.
As you might imagine, geraniums like moist, but not water-logged, soil. They're very susceptible to root rot disorders.
To maintain adequate soil moisture, pot geraniums in containers no smaller than 16 inches in diameter.
Larger — 24- to 36-inch diameter — pots are better. Use three to five plants per pot, respectively. Some crowding seems to result in more flowers and more vigorous plants.
The most frequently sold geraniums are the common and zonal types. These grow upright, each plant having a number of flowering spikes with large, softball-size bloom clusters in red, pink, salmon and white.
Some varieties have colors nearly florescent in their intensity and brightness. Ivy geraniums are also popular.
Like common and zonal forms, ivy geraniums hold their flowers well above the leaves on stiff flower spikes. The blooms are smaller but still showy. Ivy geranium leaves are thick, stiff and dark green, and the stems cascade down, making them ideal for planter boxes and hanging baskets. Ivy geraniums also come in purple.
Ivy geraniums grow best in full shade during the summer and partial shade to full sun in winter. Because they're less heat tolerant than common and zonal types, it's best to discard them in May and buy new plants in the fall.
Gardening
Advice by John P. Begeman
» Demonstrations
"Great Trees for Tucson" will be the topic for this week's garden demonstrations:
• Wednesday — 9 a.m. UA-Pima County Cooperative Extension, 4210 N. Campbell Ave.; 1 p.m. Wilmot Library, 530 N. Wilmot Road.
• Friday — 1 p.m. Oro Valley Public Library, 1305 W. Naranja Drive.