Heuchera

Often, when people are in my gardens, they will ask "So, what's your favorite plant?" My response is generally something on the order of "Why, all of them, of course". There are some that are a little closer to the top of the list than others, though. Among those top ranking plants is the entire species of Heuchera (hew-ker-a), also known as alumroot or coral bells. Heuchera are nicely behaved perennials that will perform in even some of the toughest conditions. And, I have some tough growing conditions at Wiese Acres.

Palace Purple Heuchera planted with hostas and aruncus under a box elder maple tree

Heuchera grow about a foot tall and one to two feet across in a round, generally uniform mound, with a tough, woody crown at the base of the foliage. Most cultivars are cold hardy to zone 4, with many hardy to as low as zone 3. They may struggle a little in the hottest zones, with most being heat and humidity tolerant to zone 8, but there are a few cultivars that do ok even in zone 11.

Heuchera flower in late spring to early summer, generally with small white, pink, or red bell-shaped flowers that grow on stalks which rise well above the foliage. Most of the more modern cultivars are grown for their foliage.  Heuchera sanguinea is the old-fashioned garden Heuchera with bright green leaves and tall spikes of bright red flowers. It is an attractive enough plant, but it began to pale with the introduction of  'Palace Purple' with its large, purplish-brown leaves. Now, you can find Heuchera with leaves of purple, rose, lime green, gold and many variations in between.

Regardless of the cultivar, the desired growing conditions are virtually the same. Heuchera are drought tolerant once established. They despise being water-logged, especially during their winter dormancy and good drainage is an absolute must. I have one garden that ends up under water for a few weeks each spring when the snow first starts to melt and the ground is still frozen so the moisture can't soak in. While all other growing conditions are perfect for Heuchera, they will not survive in this garden. If I want to have some of their beautiful foliage there, I need to plant them in the spring and consider them annuals for that growing season, or dig them up and transplant them to a new location each fall. Any that I leave in the ground over the winter end up a soggy, rotted mess by the time the water finally soaks away.

Heuchera Container Plantings

I also use Heuchera in my shade planters; another way I can have their bright spots of color in areas otherwise inhospitable to these plants.  It's also a great way to make your container plantings nearly carefree. Heuchera don't require watering as often as thirstier container plants, they require very little deadheading, and their color lasts all season long.

Late fall planting using hostas, ferns, and Heuchera from container planting

In the fall, when container season is finished, I lift the plants and put them into the ground in a location where I need their splash of colorful foliage. They need to be planted while there is still at least six weeks of ground temperatures above freezing, and they require mulch their first winter. This is a great way to get double duty out of your container planting, though.

Many Heuchera cultivars will tell you they are good for full sun to partial shade.  I grow nearly forty different Heuchera cultivars at Wiese Acres and I haven't found a single one that does well in full sun. They all suffer if exposed to hot afternoon sun. We have hot summers here in North Dakota and the intense western sun burns the leaves, making the color fade at the least, and turning them crispy at its worst. So, do your Heuchera and your budget a favor and plant them only where they will have afternoon shade. They'll be happy and so will you.

As Heuchera grow, the crown tends to lift itself out of the soil. In cold winters, Heuchera may require mulch to protect the crown, or even require lifting and replanting at a deeper level before the soil freezes if the crown is really exposed. As with most of my plants, I leave the old foliage on over the winter months to help catch snow and protect the crown. While many people consider this optional with most plants, I would recommend that you consider leaving the old foliage over the winter an essential part of your Heuchera's care. Many of the plants will come through the winter with intact foliage. In the spring, you can either trim them fully back to the crown to keep them in a little neater mound, or just trim the most tattered leaves back.

Other than that, Heuchera are relatively care free. I've not had to deal with any diseases (other than rotting crowns from poor drainage in my wet garden) or pests. Heuchera can be attacked by strawberry weevils. This small cream colored c-shaped grub eats the roots of the plant so that the foliage falls off in the spring. You can spot the little buggers by digging down into the soil and looking for them. To control them, you need to do double control for the larvae and for the adult dark brown - black beetles that appear and chew on the leaves, generally in late May or early June  Spray the beetles with a systemic insect control, such as Bonide. They are active at night, so that is the best time to spray.  The larvae can be killed by adding beneficial nematodes, such as NemaGlobe in a spray around the planting area in the fall. The larvae can also be killed by pouring boiling water on the soil where you have found the infestation. Just keep in mind that if you have any plants in that area, the boiling water will most likely kill them, too.

Mildew and rust can also attack some varieties of Heuchera. Rust appears as spots that look, well, like rust, on the leaves. The spots will look dark from the top of the leaf, but if you turn the leaf to the back side, you will see tell-tale orange patches. This is a problem that is likely to occur when there are periods of high moisture and cool temperatures in the 45 to 50 degree range.  Rust won't kill the plant, but it is unsightly and can spread quickly. A spray of baking soda dissolved in water may prevent rust from setting up housekeeping if used preventatively during those cool, damp times. Copper-based fungicides will also help prevent and treat rust.  Remove the affected leaves and spray according to label directions.

Mildew leaves a white or gray powdery substance on the leaves. It can also be slowed down with the baking soda or fungicide spray, but is best prevented through good drainage, adequate space between plants for sufficient air movement, and a growing area clean of debris. Lighter leaved Heuchera tend to be more susceptible to these diseases than the darker leaved varieties, so it is especially important to follow good growing practices with these.

Heuchera can be divided after just two years' growth, if you wish, but should be divided every three to five years at least. A good indicator that it is time to divide is when the center of the plant starts to look ratty or begins to die off. Heuchera are best divided in the spring by digging the clump and using a sharp shovel or knife to cut the clump into as many divisions as you wish.  Replant the divisions up to the crown, watering in well after planting. If foliage wilts, trim it back to the crown to give the roots more energy for growth. Before long, you will have even more beautiful Heuchera.

For my part, this year I am on the lookout for even more new varieties of Heuchera to place in dry, shady spots at Wiese Acres. In my next blog installment, I'll tell you about some of my favorite Heuchera and the new cultivars I hope to try.