Archive | February 2018

Vegetables: Sweet Potatoes are Super Foods!

by Lisa Johnson, horticulture educator for Dane County UW-Extension

landscape-1506015991-baked-sweet-potatoes-1Did you know you could grow sweet potatoes in USDA Zone 5a, 5b, and 6 in Wisconsin? Sweet potatoes, or Ipomoea batatas, are tender, warm-weather plants related to morning glories. They come from Central and South America, and need a long, warm growing season. They grow on trailing vines, with bush-type varieties for smaller spaces.

Usually you buy what’s called sweet-potato slips, which are unrooted cuttings. They arrive by mail, 4-6 inches long, for planting in late May to early June. Soil temperatures should be a minimum of 55º F, 3 inches down for best rooting. Test this with a soil thermometer.

Strip off the bottom leaves, leaving one node (growing point) and a couple of leaves on top. Plant node-end up, 3 inches deep in mounded rows about 18-24 inches apart. Leave 36 inches between the center of each row, or plant in hills with three or four slips per mound.

If the soil is dry, water it before and after planting. Keep slips moist while rooting, but drier once established. Don’t water the last three to four weeks before harvest. Watch out for voles because they love the roots!

sweet-potatoes-freshly-dugHarvest sweet potatoes before danger of frost in late September or early October. Handle roots carefully; they bruise easily. Gently remove dirt clods without rubbing. Don’t wash them before curing.

Curing sets the skin, heals wounds, and converts starches to sugars. Curing allows the roots to store much longer than those uncured. Ideally, cure them in a warm area for 10 days at 80º to 85º F and high humidity (85 to 90 percent), or next to a running furnace for two to three weeks at 65º to 75º F. Once cured, store in a dark location at 55º to 60º F. Don’t refrigerate! Wrap cured sweet potatoes in newspaper and store in a cool closet or basement. Store properly, they can last six to 10 months!

Sweet Potatoes Recommended for the Lower Half of Wisconsin

Cultivar Name                 Days to Harvest                                   Root & Flesh Color

  • Beauregard                     100                                        light purple skin, dark orange flesh
  • Bush Porto Rico               110                                             copper skin, orange flesh
  • Centennial                      100                                                   orange skin, flesh
  • Jewell                             100                                                        orange flesh
  • Vardaman                       110                                              golden skin, orange flesh

Planting Pots: Clay or Plastic, and a few other options

Clay (Unglazed Terra Cotta)

Advantages:  Weight of the clay adds stability; pots in the classic tapered shape are less likely to tip over than are tapered plastic pots. Porosity enables water to evaporate, which has two benefits: roots are less likely to drown if the plant is overwatered; and evaporation cools the pot, helping to prevent overheated soil.

Drawbacks: Clay is heavy, even before you fill it with soil. Evaporation means plants must be watered more frequently. Fertilizer salts build up on the outsides and rims of clay pots. And they are breakable. Another fault, though not of the clay itself, is that many good-looking clay pots are designed more for beauty than use: a pot that is narrower on top that it is at its widest point will probably have to be broken if the plant in it needs potting up.


Advantages: Lightweight. Inexpensive. Easy to clean and compact to store. Plants in plastic need less-frequent watering. Fertilizer salts do not build up. Plastic is not unbreakable (in fact, many plastic pots become brittle after a few years), but it’s not as fragile as clay.

Drawbacks: Tippy, especially if the plant is attractively large in proportion to the pot. Holds water so well it increases the danger of water-logging. Can overheat in a sunny spot, especially if the plastic is a dark color. There are now pseudo terra-cotta ones, complete with fake fertilizer sales, that look pretty convincing from a distance. But the beauty bottom line is still, well — they’re plastic.

Other Materials

Glazed clay pots don’t transpire water as fast as unglazed ones, but they still provide more evaporation than plastic. Salts are less of a problem on glazed clay. These pots can be gorgeous, but that’s not always a plus. Pots are there to support the plants; beware of using one that’s so pretty it upstages its contents.

Glass is uncommon for good reason, as it combines the faults of clay and plastic without offering the benefits of either (unless you count weight).

Galvanized metal tubs will rust where the seams are, no matter what the literature says, and Wood will rot. Containers made of these materials should be lines with heavy plastic and used as cachepots.


Tips on Putting Pots in Pots

  • The outer pot is called a cachepot, from the French for “hide pot,” and it can be made of any material, in any shape. As long as you can put a potted plant in it, it qualities. Ironically, the one thing it is unwise to use is a valuable antique cachepot — or actually, a valuable antique anything. The minerals and algae that tend to collect on the inside of cachepots can discolor porcelain, bond to metal, or otherwise cause irreversible damage. Plastic lines are not reliable damage preventatives, though if you are determined to use an antique, a liner may help protect it.
  • If the outer container is china or glass, use a plastic pot inside to minimize the chance of breakage if the interior pot hits it. If the outer container is metal, wood, or straw, line it with plastic for protection against rot, and use clay for the inner pot to give the plant roots a slightly better chance to breathe.
  • Prop up the inside pot. Water is going to run out of it and collect in the cachepot, and if the plant sits in water constantly, the roots are likely to rot. Any water-resistant elevator will work: a piece of brick, an overturned saucer, or a short stack of plastic deli tubs (open end down). You can also just use a thick layer of pebbles, perlite, or styrofoam beads, though loose materials like these make routine maintenance more difficult.
  • Remember to lift out the plant and empty the cachepot frequently; that water can get nasty. And if the assemblage is outside, mosquitoes can breed in it. Outdoor cachepots should contain small chunks of Mosquito Dunk (a biological control organism, widely available at garden stores).


Snow Birds

by OCMGA Master Gardener Tammy Borden

Winter is here. That means that most Ruby-throated hummingbirds have flown south to another whole continent, along with Baltimore Orioles, Rose-breasted Grosbeaks, Indigo Buntings and a host of other feathered friends we won’t see until Spring or early Summer. But that doesn’t mean we can’t longingly peer out our kitchen window in hopes of seeing some other feathered delights!

Winter Visitors


Dark-eyed Junco

Believe it or not, Wisconsin winters are a “retreat” for some birds. There are several species of birds that migrate for the winter south to Wisconsin from Canada. One of these birds is the very common Dark-Eyed Junco. It is a beautiful small gray bird with a white belly. They are easily recognizable at bird feeders, feeding on thistle, cracked sunflower, and other smaller seeds. They are more often ground feeders. They love snow. I have seen them practically playing in a blizzard.

Another winter visitor is the Redpoll, a member of the finch family. Redpolls will not visit every winter. In fact, I only saw them for one season about ten years ago when Canada was experiencing an unusually harsh & frigid winter. In these cases, Redpolls will migrate south to Wisconsin in search of food. When they appear it’s called an irruption. It is almost like they are refugees in a foreign land.

White Throated Sparrows are another favorite sight on a dreary winter’s day. They are


White-throated Sparrow

commonly seen in winter in Wisconsin and at first glance may look like a plain old house sparrow. But not so! Look closely and you will see the white throat, yellow patches near its beak and the black and white stripes on its head. They prefer foraging on the ground rather than sitting on a feeder, so be sure to scatter some seed at the base of your bird feeder.

Goldfinches … “What?” you say. Many people believe that those “wild canaries” leave for the winter and are replaced with brown sparrows. Goldfinches remain in Wisconsin for the winter but lose their summer plumage. Continue to put out thistle seed for goldfinches and come spring, you will have a backyard of sunshine.


Rule number one: all living things need water, and providing a source for birds is critical in the winter months. Many heated bird baths are available from various retailers and can range anywhere from around $30 to over $100 depending on how fancy you want to get. The key if you get a bird bath heater is to make sure it is thermostatically controlled. This will help save on energy bills and only heat the water when temperatures are freezing. I have often looked out my kitchen window on a freezing morning to see birds perched all the way around my bird bath. It’s a wonderful sight to see.


Birds in winter need to maintain as much body fat as possible. So it’s important to provide food that will help keep a bird’s metabolism up to keep warm. One of the best sources of fat and protein for birds is suet. Keep lots on hand in the winter. Woodpeckers love it and their stark plumage adds color to your life.

As far as birdseed is concerned, I recommend not purchasing inexpensive bird seed mix. Check the ingredients! Many mixes contain filler seeds like Milo and millet. A small amount of millet is okay, but Milo is a seed with an extremely hard shell that is almost impossible for most birds to open. Some cheap birdseed mixes contain up to 35% Milo, which is practically all waste material. In addition, it has very poor nutritional value. Personally, I just purchase plain old black sunflower seed for my larger feeder, and thistle seed for my tube feeder. These basics have worked well for me. I have also purchased some nicer mixes and combined them with a larger bag of sunflower seeds to offer some variety.

Remember to shovel away or press down the snow underneath feeders to help ground-feeding birds. Scatter some additional seed on the ground.



Black-capped Chickadee

An important aspect of birding in the winter is to provide protection. Small birds are more vulnerable to hawks and predators in the winter because there is less cover. Some of this may require planning ahead by planting dense shrubs, evergreens and wind breaks. However, a simple way for those who use real Christmas trees is to simply place your tree about 10-15 feet from your feeder after the holidays are over. Another way to provide protection is to make or purchase a roosting box. Smaller birds like chickadees will use them to huddle together at night when resting and to escape the winds. Other possible cover includes wood or brush piles.

Don’t forget your feathered friends this winter! I’ve generally found that the more birds you have, the more birds you’ll get! By feeding them through the winter you’ll have a better chance in the spring of seeing new species dropping in to see what all the chirping is about!

Ground Covers

What is a Ground Cover?

Groundcover_6695A ground cover is any low-growing plant or group of plants that will make a living blanket over the area in question, crowding out weeds while providing visual interest. Most of the more common ground covers are rapidly spreading, long-lived perennials with soft stems, such as pachysandra, but low-growing woody shrubs like spreading junipers are often used also.

Ground Covers for Shade

Among the hardy herbaceous ground covers that are superb for shade are the European wild ginger (Asarum europaeum), which has rounded, glossy evergreen leaves and grows about 6 inches high, and barrenwort, or bishop’s hat (Epimedium spp.), which has semi-evergreen leaves that seem to flutter over its wiry stems.

Consider also lilyturf (Liriope muscari), with grassy evergreen foliage, and sweet woodruff (Galium odoratum), whose starlike leaves are, as its name suggests, fragrant; and an assortment of hostas.



There are a number of low-growing woody plants that are also good ground covers, including bearberry (Arctostaphylos uva-ursi), whose tiny evergreen leaves often turn red in autumn; several herringbone-patterned cotoneasters (including Cotoneaster horizontalis) and C. dammeri; and the St. John’s wort called Aaron’s beard (Hypericum calycinum), whose yellow flowers dot its dark leaves through the late summer.

Covering Hot, Stony Ground

When you say hot, dry, and stony, you’re describing the perfect environment for creeping thymes. There are dozens of these gracefully spreading, tiny-leaved plants, many with strong scents other than that of the classic herb.

Choices include lemon-, coconut-, caraway-, and lime-scented varieties. Or if you don’t want to grow hungry every time you take a step, there is a well-named wooly thyme, which has only a light fragrance. It forms a very low mat of silver-green fuzz that makes you want to stoop down and pet it.

Over Exuberant Ground Covers

Beautiful, easy, quick to spread. When you read these words in the catalog, they sound very enticing. But be careful what you wish for. Many of the most common ground covers are actually hell-bent on covering the earth. Once they have taken hold in the garden, they are very hard to eradicate, and there’s a good chance that they won’t stop when they reach the property line.

  • Bishop’s weed, or goutweed (Aegopodium podagraria)
  • Creeping bugleweed (Ajuga reptans)
  • Crown vetch (Coronilla varia)
  • English ivy (Hedera helix)
  • Houttuynia (Houttuynia cordata)
  • Indian strawberry (Duchesnea indica)
  • Mint – especially spearmint (Mentha spp. – M. spicata)
  • Spotted dead nettle (Lamium maculatum)
  • Vinca, or periwinkle (Vinca minor)
  • Wintercreeper (Euonymus fortunei)