Windy City Cactus: Eastern Prickly Pear Cactus

When you think of Chicago, you probably don't think of sand dunes, prairies, or large oak trees.  Yet despite Chicago being the third largest city in the United States and heavily impacted by urban sprawl and industrial blight, there remains thousands of acres of greenspace with wetlands, open woods, sandy beaches...and some rather surprising flora.

The pictures below were not shot in Arizona nor in Southwest California, but were in fact taken at the 63rd street beach on a recently restored sand dune near Hyde Park in Chicago, Illinois.  They are the eastern prickly pear cactus (Opuntia humifusa).


Figure 1:  Eastern prickly pear cactus, a native plant to the Chicago region and the only native cactus to the Great Lakes area.  
The genus Opuntia is much more common out west where they have many different species, but in the Great Lakes and Midwest regions, the eastern prickly pear is the only native cactus.  It tends to be a little bit smaller than its western counterparts, although I have seen some rather large ones growing along railroad tracks in nearby Indiana.   In the late spring, usually towards the end of May and into the beginning of June, eastern prickly pears will produce a showy yellow blossom that only lasts a day or two before going into fruit (see figure 2).  Their bright yellow flowers are swarmed by bumblebees (Bombus spp.) and other pollinators.

Figure 2:  Prickly pear flowers
The flowers develop into edible fruits that are sweet and juicy.  In fact, the entire plant is edible and the spears can be cooked or juiced.  I have yet to figure out how to harvest this plant safely, as each spear is armed with very sharp thorns and bristles.  Perhaps some courage and a few minutes of watching instructional Youtube videos will do the trick.

People frequently ask me how it is possible for prickly pear cactus to be growing in Illinois in the wild.  Indeed, most species of Opuntia grow in hot and dry climates with mild winters.  In the Chicago region, prickly pear cactus usually grows in well drained sandy soils with abundant sunshine and where there is a small amount of slumping of the substrate.  In the winter, eastern prickly pears will shrivel up as they are smashed down by snow and ice.  They awaken from their dormancy in the spring where they "re-inflate" their spears.  This adaptation combined with their slightly smaller size helps them adapt to Chicago's cold temperate climate.  

If you live in the Southern Great Lakes Region or anywhere east of the Mississippi and south of the Canadian border, you can probably grow eastern prickly pear cactus right in your own backyard (figure 3)!  Planting them is easy.  Hold a spear with a pair of tongs or sturdy tweezers and stick it in a pot with a mix of 75% sand and 25% potting soil.  Give it just a little bit of water and that's all you need!  The spear will start setting in roots within a few weeks or so.  After it does, locate a dry area in your yard or community garden that gets ample sunshine for at least 6 hours per day.  If your garden is wet, you can compensate for this by using sand or pebbles as a mulch around the cactus so that water will drain away more easily.  You will impress your Midwest neighbors with a plant that is native to the region but looks more like it belongs in Texas or Mexico.  Just watch out for those thorns!

Figure 3:  A thicket of eastern prickly pear cactus planted outside of the Sand Ridge Nature Center in South Holland, Illinois.  

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