Extension News

Ask the ISU Extension Garden Experts: Tomatoes, Beets and Japanese Beetles

Note to media editors: Got gardening questions? Call the Hortline at (515) 294-3108, Monday-Friday from 10 a.m. to noon and 1 to 4:30 p.m., or e-mail us at hortline@iastate.edu. For more gardening information, visit us at Yard and Garden Online, http://www.yardandgarden.extension.iastate.edu

5/7/2009

What is the proper way to plant tomatoes?

Plant tomatoes in the garden after the danger of frost is past. In central Iowa, it's usually safe to plant tomatoes around May 10. Gardeners in southern Iowa can plant one week earlier, while those in northern counties should wait an extra week. The last practical date for planting tomatoes is approximately June 20.

Plant tomatoes in full sun. The planting site should receive at least six hours of direct sun each day. If the plants are in peat pots, tear off the top edge or make sure the top edge is well below the soil surface once planted. If the top edge of the peat pot is exposed to the air, it will act like a wick and draw water from the soil around the plant. If the tomatoes are in plastic pots or cells, carefully tap out the plants.

Set plants into the soil up to their first true leaves. Pinch off the bottom leaves of tall, lanky transplants and lay them sideways in a trench. Carefully bend the stem upward so that the upper few inches of stem are above the soil surface. Roots will develop all along the buried stem.

Spacing of plants depends on the growth habit of the variety and training system employed. Indeterminate tomatoes grown in wire cages should be spaced two to three feet apart, while a three- to four-foot spacing would be appropriate for indeterminate tomatoes allowed to sprawl over the ground.

Determinate tomatoes can be planted two to 2-1/2 feet apart. Rows should be spaced about four feet apart.

I haven't had much success growing beets. What can I do to ensure a good crop?

Beets perform best in loose, well-drained soils in full sun. The planting site should receive at least six hours of direct sun each day.

The most common problem growing beets is not thinning the planting. Proper spacing is essential for a quality crop. Thinning is especially important for beets since every beet is actually a fruit that contains several seeds. Thin the beet planting when the seedlings are three inches tall.

Remove the smaller, weaker seedlings and leave the stronger, more vigorous plants. After thinning, plants should be spaced three to four inches apart.

Poor germination may be another problem. Poor germination may result from the crusting of the soil surface or dry soil conditions. Crusting can be prevented by lightly mulching the seeded row with sawdust, peat moss or dry grass clippings. Water the row during dry weather to promote germination.

Are there any landscape plants that won't be attacked by Japanese beetles?

Japanese beetles feed on more than 400 species of plants. Commonly attacked plant hosts include peach, cherry, plum, apple, linden, birch, elm, Norway maple, horse chestnut, willow, grape, raspberry, Virginia creeper, rose, hollyhock, hibiscus, dahlia and zinnia.

Plants that are rarely attacked by Japanese beetles include red maple, magnolia, white oak, red oak, common lilac, burning bush, hydrangea, forsythia, rhododendron, boxwood, holly, juniper, arborvitae, yew, fir, spruce, pine, impatiens, begonia, ageratum, columbine, sedum, coral bells and coreopsis.

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Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu 

Del Marks, Extension Communications and External Relations, (515) 294-9807, delmarks@iastate.edu