Published in the Contra Costa Times on May 10, 2008
Question: I planted bush bean seeds several weeks ago, but nothing has come up. I have been watering every day, and I added lots of compost to the bed. How long does it take for beans to sprout? The seeds were a couple of years old. Are pole beans easier?
Answer: Beans can be easy to grow as long as you have soil that drains well, a bed that gets full sun, the soil temperature is at least 60 degrees and the air temperature is above 70 degrees.
Clay soils stay colder longer, and bean seeds will often rot before they can germinate. Compost is a good idea, but can help keep the soil moist, which can also contribute to the rotting problem. Beans like soils with a pH above 6.0, which is not a problem in most parts of the county, but check if you are not sure.
Bean seeds can take two weeks to sprout, and need to be kept moist, but not soggy. Once the beans have sprouted, you can reduce the watering schedule to once-a-week deep soaking.
If you have difficulty getting the beans to grow, you might want to pre-germinate the seeds. This is done by placing the seeds in a Ziploc-type bag on a damp paper towel folded in half. The bag should be placed somewhere warm, like on top of the refrigerator.
Plant the beans in your prepared bed when you see the emerging root radicle, about 1 inch deep and 2-5 inches apart.
If your seeds are older and have dried out, soak them for several hours in tepid water before placing on the damp towel. Bean seeds lose vigor after several years if not stored in ideal conditions.
Beans are one of the plants that are capable of getting their own fertilizer from the air with the help of a beneficial Rhizobium bacteria. The bacteria form pink-centered nodules on the roots of the beans, where they take atmospheric nitrogen and convert it to ammonium, a form the plants can use. This may be the perfect marriage. You can purchase type D inoculum and dust the bean seeds with it prior to planting; however, do not use this on bean seeds treated with fungicide, as it is toxic to the good bacteria.
If you want to harvest bush beans through the fall, you will want to plant successively every couple of weeks. Bush beans are determinate plants, which means they flower, set fruit, then are done for the year.
Pole beans require the same conditions that bush beans need. The advantages are that you can grow the beans on trellises or on bamboo pole teepees, which take up less garden space than rows of bush beans. Pole beans are indeterminate, and bear over a much longer period of time as long as you keep the beans harvested.
There are many wonderful heirloom beans - both bush and pole - available now from a wide variety of sources.
Bethallyn Black is director of the Contra Costa Master Gardeners, a program associated with the University of California Cooperative Extension and supported by Contra Costa County. Reach her at bblack@ucdavis.edu, or 925-646-6586. General questions for the Master Gardener should be sent using our Question Form