How to Build a Perennial Garden That Actually Gets Better Every Year
The secret of a nice perennial garden is get your zone right‚ amend your soil before you plant‚ and have a combination of plants that flower at different times of the garden season so there's something in bloom all the time․ Get that down‚ and maintenance is pretty simple after the second season․ So if you happen to miss a few of them you could be replanting the same area every spring wondering why nothing came back․
The USDA Plant hardiness zone in Tennessee ranges from zone 6b to zone 8a․ Nashville and Knoxville are in hardiness zone 7a‚ while Memphis and the Mississippi River floodplain are in zone 7b and 8a respectively․ A plant rated hardy to zone 5 will usually take our winters‚ although a plant rated hardy to zone 8 at a minimum can be killed by a hard freeze on the Cumberland Plateau․ If listing using the tags‚ use your county's hardiness zone‚ not Tennessee․
What are the benefits of investing in perennials?
Whereas an annual plant goes from seed to bloom to seed again within a year‚ perennials die at the end of the winter and bloom again from the same roots in the spring‚ getting bigger and fuller and bushier each year․ A perennial bed initially prepared well will require less watering‚ fertilizing and weeding than an annual flower bed in its second and third years․ Less work‚ more color‚ year after year․
They have various responses‚ including being treated as a line of plants along a footpath‚ as part of a mixed border‚ naturalized on a slope‚ or growing in a patch of ground far enough from the lawn mower's reach that it stops being a lawn‚ but which is still well drained and sunny․
You need a real plan‚ not just a plant list
Walk around your yard and note the sun position at three points in the day․ For example‚ a full sun site at noon may not be full sun at 4 pm if a maple is shading the site in the afternoon․ Many of the most suitable plants for full sun‚ such as coneflower‚ black-eyed Susan and daylily‚ are most vigorous when they receive six hours or more of sunlight each day․ Otherwise‚ the plants may become leggy and produce few flowers․
This is the size of the plant when fully grown․ If bought as a 1-gallon pot‚ small coneflowers at 8 inches will quickly grow to 3 feet high and wide․ Crowded plants compete for the same space and will be fighting for room two years from now․
Getting the soil and nutrients right beforehand․
Most of Tennessee has clay soil‚ especially in Middle Tennessee‚ which must be drained for improved drainage‚ because clay is wet‚ and it may take days to dry out after rain․ If planting in the garden‚ mix in 2 or 3 inches of compost or well-rotted animal manure into the soil of top 8 to 10 inches․ If your garden site is a low spot that becomes puddled on rainy days‚ consider building a raised bed‚ or plant perennial beds with astilbe or Joe Pye weed․
Have a cheap soil test done at your UT Extension office to determine pH․ Most perennials prefer a soil pH of 6․0 to 7․0․ If you're consistently below this‚ then adding a little lime should help‚ and if you're too high‚ then adding some sulfur can help․
Stagger Bloom Times So Color Never Stops
This is the mistake so many gardens make: everything flowers in June and then the bed is tired out for the rest of the summer․ Layer your bloom calendar!
The first blooms appear in March and April: creeping phlox‚ bearded iris‚ and peonies bloom in the coldest air․
Other flowering plants that may be in bloom during late spring and early summer (May through June) include daylilies‚ coreopsis‚ and salvia․
Mid to late summer (July and August): Coneflower‚ black-eyed Susan‚ and bee balm will stand up to the heat and the humidity of summer in Tennessee better than most․
Fall (September to October): The sedum‚ asters, and anemone are among the very last flowers when gardens come to an end․
Plant in drifts of three to five of each kind rather than one here and there‚ which looks a little more haphazard than by design‚ and will give pollinators a reason to visit you․
Don't overlook the shady corners
Every yard contains at least a little shade․ Maybe it's under a tree‚ maybe it's in front of a shady north-facing fence or wall‚ or maybe it's behind the garage․ Use it if you can․ If blooms do not have the desired effect‚ hostas‚ ferns‚ coral bells and bleeding heart can take the shade and give foliage․ The TN Nursery provides a list of plants for shade․ If you are planning a shade garden‚ or waiting a year for a better growing season‚ knowing the difference between deep shade and dappled shade is essential․
Water Deep‚ Not Often
Another common error is watering a little bit every day․ In Tennessee's hot August weather‚ that just teaches roots to stay in the top of the soil column‚ making them most susceptible to drought․ In the first year‚ water weekly or bi-weekly with 1 inch (2․5 cm) of water at a time until the roots are established․ Established perennials require supplemental watering only if it has not rained for 2 weeks or more․
Divide Before Plants Decline
Most perennials that form clumps‚ such as daylilies‚ hostas‚ coneflower‚ and black-eyed Susan‚ should be divided every three to four years․ Signs that a perennial should be divided include a donut hole in the center and the plant producing fewer flowers than it did in previous years․ If it becomes overly crowded‚ you can divide it in the spring or early fall by taking it up out of the ground and separating the healthy portions on the outside by using a spade or your hands․ Then you've got free plants for another part of the yard or for a new garden․
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