November 2011 Gardening Q&A

Storing up for winter

by B. Rosie Lerner
Purdue Extension Consumer Horticulturist

Questions abound about moving garden's bounty indoors

Q: I had to harvest quite a few tomatoes that weren’t quite ripe yet to avoid the frost. What can I do with these now? — M.J.

A: Tomatoes will continue to ripen off the vine if they have reached the critical stage of development called mature green. If the tomatoes have not hit that stage yet, they will remain green once removed from the plant.

Mature green tomatoes are about normal size and have a whitish-green skin color; however, they can be difficult to judge if you don’t have immature green ones for comparison. If there is any hint of a blush of color change your tomatoes have reached mature green. If you want to hold the tomatoes for longer storage, keep them between 55-65 F. Mature green tomatoes will keep three to five weeks by wrapping them individually in newspaper before storing. Inspect weekly for ripeness. Raise temperature to 65-70 F for faster ripening.

Q: Will sweet potatoes “keep” all winter if they are not first “cured”? How do you know if they have been cured properly? — M.D.

A: Sweet potatoes will keep well through the winter if they are properly handled through harvest and storage.

Sweet potatoes should be carefully dug to minimize injury and properly cured, to heal wounds and improve flavor, before storing. It is during the curing process that starch is converted to sugar.

Cure sweet potatoes by holding them for about 10 days at 80-85 F and in high relative humidity (85-90 percent). In the absence of better facilities they can be cured near your furnace. If the curing area’s temperature is between 65-75 F, the curing period should last two-three weeks. To maintain the required high humidity (85-90 percent), stack them in storage crates or boxes and cover with paper or heavy cloth. Packing in perforated plastic bags will also keep humidity high.

Once sweet potatoes are cured, move them to a dark location where a temperature of about 55-60 F can be maintained during storage. Sweet potatoes are subject to chilling injury so keep them out of the refrigerator. Outdoor pits are not recommended for storage because the dampness encourages decay. Wrapping cured sweet potatoes in newspaper and storing them in a cool closet can also provide good results.

More information is available online at http://www.hort.purdue.edu/ext/sweetpotatoes.html and http://www.hort.purdue.edu/ext/HO-136.pdf.

Q: I have Concord grapes, and this year the clusters seem to have a lot of berries that take longer to ripen than others. Can you pick individual grapes, or should you always pick the whole bunch, no matter whether they are all ripe or not? — Brad M.

A: While you could pick individual grapes, it is awfully tedious so it’s not typically done that way. Uneven ripening is when some of the berries in the cluster remain sour, hard and green while others develop the purple color and soften during the ripening process. The green berries will be full-sized but not sweet.

For some reason those berries never go through the increase in sugar and decrease in acids that commonly occurs during fruit ripening. It is not clearly understood why this phenomenon occurs, but it mostly happens only in Concord grapes. Hot weather appears to be partly responsible.

More information on growing and harvesting grapes is online at http://www.hort.purdue.edu/ext/grapes.html and http://www.hort.purdue.edu/ext/HO-45.pdf.

Q: I have five to seven peony bushes that have large black spots on the leaves. The past two years, I did not have very many blooms on these older bushes. Could you tell me what is the cause of these black spots and how to remedy this problem? Also, I have a peony bush that I transplanted from a very shady spot to full sun about three to five years ago. The bush is getting larger and fuller but has not bloomed. Is there a way I can make this bloom? — Bonnie Holt.

A: Peonies in Indiana are quite likely to develop a fungal disease called leaf blotch, also known as red spot and measles. Discolored blotches (lesions) occur on leaves or stems and may start as tiny red spots (measles) but eventually progress to larger brown or purple blotches. It is not unusual for the peony plant to be completely defoliated from this disease by the end of summer, but, surprisingly, the plant seems to be able to tolerate the infection.

The fungus survives the winter in infected plant debris and produces spores in the spring, which are then splashed onto young foliage and stems through rainfall or overhead watering. Remove dead plant residue in late fall or early spring before new growth emerges to reduce the severity of this disease next season. When possible, use drip irrigation to minimize fungal infection. The Purdue Plant and Pest Diagnostic Lab has additional information on peony leaf blotch at http://www.ppdl.purdue.edu/PPDL/weeklypics/8-20-07.html.

The transplanted peony may have been set too deep, or perhaps it has been heavily mulched. Peonies planted too deep will produce foliage but may never bloom. The buds of the tuber should be set no deeper than two inches below the soil surface. More information on growing peonies is at http://www.hort.purdue.edu/ext/ho-76.pdf.

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