How do I over-winter cannas indoors? 
Cut the plants back to within 4 to 6 inches of the ground a few days after a hard, killing freeze.  Then carefully dig up the canna clumps with a spade or garden fork.  Leave a small amount of soil around the cannas.  Allow them to dry for several hours.  Afterwards, place the cannas in large boxes, wire crates, or in mesh bags.  Store the cannas in a cool (40 to 50F), dry location. 

Are ornamental sweet potatoes edible? 
Ornamental sweet potatoes and sweet potatoes grown in the vegetable garden are different varieties of Ipomoea batatas.  The ornamental varieties are grown for their attractive foliage, while those in the vegetable garden are grown for their delicious roots.  

The roots of ornamental sweet potatoes can be eaten.  However, the ornamental varieties were selected for their attractive foliage, not their culinary qualities.  The culinary qualities of the ornamental sweet potato roots may not measure up to their vegetable counterparts. 

What would cause my lilac to bloom in late summer?
The flower buds on many trees and shrubs form in mid-summer.  Stressful conditions in summer, such as hot dry weather, may induce plants to become semi-dormant.  Rain and cooler temperatures in late summer/early fall may revive the semi-dormant plants and coax a few flower buds to open.  Saucer magnolias commonly produce a few flowers in late summer.  Occasionally, a few crabapples and lilacs will also produce a small number of flowers in late summer. 

What can I do now to prevent diseases in my garden next year?
One of the most important ways to prevent plant diseases next year is to practice good sanitation now, in the fall.  As you prepare the garden for winter, remove all diseased above-ground plant material, especially from plants that are known to have had diseases this year.  Many fungi that cause plant diseases survive the winter in dead plant material, so removing it helps to prevent these fungi from surviving in your garden.  Infected plant material should be burned or thrown away.

What do I do about Asian lady beetles getting into my house?
The Asian lady beetle has become a familiar problem for many Iowans in the decade since it arrived.  Asian lady beetles overwinter in large aggregations.  In their natural habitat they prefer to overwinter in the cracks and crevices on cliff faces.  However, in Iowa we don’t have many cliffs and to the beetle a house looks close enough.  After landing on the house the lady beetle crawls around looking for a crevice and often ends up crawling into the living area of the house.  Many of the beetles end up within wall voids and will keep emerging into the house during warm spells all winter.

The Asian lady beetle migration is triggered by cold temperatures.  Usually the biggest swarms are on the first 70-80ºF days after our first frost.  Before that time you need to seal up any cracks in your foundation, holes where utilities enter the house, and make sure there is weather stripping around doors and windows.  Synthetic pyrethroid insecticides can be used outside the house to deter lady beetle entry.  We do not recommend using insecticides indoors because it is impossible to reach the lady beetles within the walls.

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Three high resolution photos are available for use with this column:

Sweet potato vine with spurge, sweetpotato.jpg, 1.2 MB
Sweet potato vine with celosia, sweetpotato2.jpg, 1.2 MB
Asian lady beetles, AsianLady.jpg. 750K