Digging In: Plant Diversity

By Jennifer Smith 

Plant diversity in the landscape means different things to different people, or perhaps I should say, to different gardeners. The Piet Oudolf Garden in Detroit has more than 100 different species of plants. The pollinator garden I designed and manage on behalf of Wimberg Landscaping at Wasson and Paxton has at least 22 different plants. 

Plant diversity to me means as many different plants as I can add without a garden becoming too disjointed or unruly looking. Truth is, at times I cross that line and I need to rein in the garden’s plant list a bit. For Piet Oudolf, an experienced nurseryman and designer creating in very generous spaces, he has the knowledge and the room to have incredible plant diversity. In his gardens, 100 different species planted in generous stands, repeated throughout the garden looks intentional, attractive and legible.

What does plant diversity mean to the home gardener, especially one who is new to gardening and doesn’t have all the time in the world to plan, plant and care for a garden? To start, I would not look at a Piet Oudolf garden and think that is your goal. Few of us would have room for 100 plant species planted in multiples. His gardens are inspirational and educational. When touring his gardens you can see fabulous plants in person and decide which you prefer and believe would do well in your garden. You can also explore local gardens, such as our Wasson Way and Ault Park garden, or the Cincinnati Zoo to review plants that are thriving here in the Queen City.  

Where Oudolf has 100 plant species, your garden could aim for 10. It’s all a matter of perspective. I would look at first increasing the quantity of plants you already have. Often, I see gardens with one or two echinacea surrounded by mulch. Start with swapping out the mulch for more of the same echinacea. Now you have more plants than mulch, a very good start, and you have a more visually impactful and nature-benefitting stand of echinacea. 

Next, I would create a plant wish list to address the seasons in the garden where you are sparse on blooms.  Choose a plant to fill that bloom vacuum and assume at least five of that plant if room allows. If you have room to add multiples of a second plant that blooms around the same time, do so, but only if you don’t risk claiming all the garden’s open space needed to fill other bloom time deficiencies. 

The idea is not to think of plant diversity as a lot of different random plants, planted in large stands throughout the garden, but a diversity of plants to ensure blooms in the landscape from early spring to the first hard frost. A wildly diverse plant offering that only blooms in the early days of spring will do little to add beauty to the landscape or support nature.  We should strive to design a garden or landscape that has blooms from spring through late fall.  

Next, I would look at adding native grasses to the landscape. Often overlooked, and not the easiest for many home gardeners to incorporate into their garden’s design scheme, native grasses are integral in carrying a garden through the four seasons while supporting nature.  Don’t shy away from annuals. Planning a garden that blooms from spring through fall takes a little time and experience, especially if you are just learning about plants and what thrives in your garden.  Annuals are inexpensive and a very colorful way to extend the bloom season of your garden. Blue salvia, cuphea, gomphrena and zinnias are a favorite with pollinators.  Finally, if room allows, consider a few native shrubs. Many of our native shrubs offer lovely blooms as well as berries which add a little something extra to the look of the garden and are most welcomed by pollinators and birds.  

Jennifer Smith is an award-winning pollinator garden designer with Wimberg Landscaping.