Neil Sperry

When is the best time to start a perennial garden? It’s sooner than you think

I’ve been called “crazy” hundreds of times before. Like the beekeeper, I’ve gotten used to the stings. So I’ll open the hive. I can hear them coming.

Fall is the best time to start a new perennial garden.

And the outcry comes back, “What?! How can that possibly be? Aren’t we supposed to plant everything in the spring? What’s this stuff about fall?”

So here is my case in support of planning, preparing and planting (the first part of) your perennial garden this fall.

“Perennials” are plants that complete their life cycles in more than one year. So a giant sequoia tree in northern California is a perennial. But when a gardener uses the term, it’s in reference to a flower or foliage plant that persists from one year to the next, bearing flowers at its flowering season year after year. Daffodils bloom in the spring. Daylilies bloom in early summer. Mums bloom in the fall.

“Annuals,” by comparison, live their entire life cycles in the year in which they are planted. They germinate, grow, bloom (usually for many months), go to seed and die, only to begin the same cycle if planted again the following year.

Some new gardeners have the mistaken idea that you can plant perennials once and forget them – that you’ll never have to plant them again. They look at perennials as being far less cumulative work. The truth is, however, that perennials require far more attention, both up front as you plan for them, and then in follow up maintenance.

Perennials bloom for two or three weeks and then they drift into the background or die to the ground entirely for the rest of the growing season. That means that you’re going to have to plan for a continuous sequence of perennial color scheduled to bloom week after week all the way through the growing season.

You’ll also have to be mindful of each plant’s flower color and growth form, and most of all height and spread as you lay out your mosaic of perennial plants. It becomes an assembly line not unlike sewing a patchwork quilt. You find that anchoring it with evergreen shrubs that can provide continuity in winter keeps it from looking blasé when nothing is blooming. Include a few fruiting hollies and a piece or two of garden art, perhaps a decorative bird feeder for motion and activity, and you will have covered all of the seasons.

So why does all of this call for fall plantings?

The old rule of green thumb is that spring-blooming perennials are dug and divided in fall and fall-flowering types are moved in early spring. Texas showcases scores of spring perennials, and that means that this is the season to be getting it all going. Major plant societies (iris, daylilies, etc.) have their sales in the fall, and the most highly regarded spring-flowering bulbs are on sale in better nurseries at this season as well.

How to plan your perennial garden

Perennial beds need to be 5 or 6 feet (or more) deep in order to accommodate larger perennials like mallows. Full sun is best for most types, but if the bed runs from sun into part shade, a good gardener can certainly find plants that will blend into that. Avoid straight lines if possible, and provide a dark backdrop.

The soil needs to be really well prepared to a depth of 12 inches. Apply a glyphosate-only herbicide (no other active ingredient) to kill all existing vegetation. Give it 12 to 15 days to do its work, then rototill to a depth of 12 inches using a powerful rear-tine rototiller.

You’ll want to add generous amounts of organic matter to any native Texas soil to improve it for new perennials. I use 2-3 inches of sphagnum peat moss, along with 1 inch each of well-rotted compost, finely ground pine bark mulch and well-rotted manure. I include 1 inch of expanded shale if I’m amending a clay soil, then I rototill all of that back into the 12 inches of topsoil until it has the consistency of potting soil. I rake the bed so that it is elevated 3-4 inches above the surrounding grade, and I proceed to do the final design for the bed.

I start with the several anchoring shrubs for the bed and where I want to place them. For example, I use dwarf Burford hollies and compacta nandinas in small clumps for natural clusters to provide winter color. If I want something taller, I may include one Warren’s Red possumhaw holly. And I may sprinkle a couple of clusters of dwarf yaupon hollies to tie a large bed together as well.

I make a list of my 20 favorite perennials. Then I determine when each of them blooms and I place them within the bed so I’ll have that continuity of color. I’m mindful to put taller types toward the back and shorter types toward the front. I look critically at the shades of their blooms so that things won’t clash when they’re flowering, but I’m prepared to change things as I go.

And I always leave holes for new plants I find in garden centers come spring. I fill those voids with winter annuals this first time around – pansies and violas, pinks and ornamental cabbage and kale.

Perennial gardens are never finished. They are constant works in progress. So hop on this crazy man’s merry-go-round with me!

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at and follow him on Facebook.