Peonies are herbaceous perennials that can bring beauty and color to the garden for decades to come, provided they have been planted appropriately. These long-lived plants are easy to care for, as long as they are grown in conditions that suit them. Understanding how far apart to plant peonies, and where to plant them, will ensure your peonies produce an abundance of blooms for many years to come.
Most herbaceous peonies have a spread of between 2 and 3 feet. This means that they should be planted 2 to 3 feet apart in the soil, since this will allow them adequate space to grow, while also creating a border that looks full and lush. Before you break ground to plant your peonies, be sure to put in the necessary work to ensure the soil is suitable, and that the positioning will work well for the peonies.
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Best Type of Soil for Planting Peonies
Peonies are fairly low-maintenance plants if you can plant them in soil that suits their needs. Peony soil must be well draining because the roots of these plants can rot easily. A well-draining soil will carry any excess water from rainfall or improper watering away from the roots, preventing the roots from being held against moisture for too much time.
The soil should ideally have a neutral pH and a generous proportion of organic matter because peonies thrive in fertile soil. You can amend the soil if it is not naturally well draining and fertile, by adding sand or perlite and working in compost to the soil. To improve drainage you can also create raised beds for your peonies because this will prevent any water from pooling around the base of the plants.
Choosing a Peony Planting Site
Peonies don’t respond well to being disturbed, so before figuring out how far apart to plant your peonies, you need to settle on the best spot. Choosing a suitable spot will mean the peonies don’t need to be moved further down the line, preventing them from undergoing the stress of being disturbed.
Peonies grow best in full sun or partial sun, depending on your growing zone. Most herbaceous peonies thrive in USDA hardiness zones 3 to 8, and some can tolerate the higher temperatures found in zone 9. If you are at the lower end of these zones with a slightly cooler climate, then a full sun position will be best for planting your peonies.
If you are at the higher end of these zones, then a partially sunny spot will be better. Ideally, in warmer climates, the peonies should be shaded in mid-afternoon, which will protect them from the sun’s hottest rays. Shade could include a nearby tall shrub or tree, a fence, a wall, or close by building.
How Far Apart Should Peonies be Planted?
Most herbaceous peonies have a mature spread of between 2 and 3 feet, though some (usually Itoh peonies) can span up to 4 feet in width. Knowing the type of peony you have and its expected spread will help you to more accurately decide how far apart your peonies should be planted.
If a peony has an expected spread of 3 feet, for example, then the plants should be planted at a distance of 3 feet between each other. If you want a very full look at your borders during the summer, then plant your peonies at a distance of 2 feet between each plant.
When the peonies are mature, the foliage from each plant will merge with the foliage of the next plant, for a lush-looking border. Peonies which are planted too close together are more likely to suffer from disease because the plants will have less air circulation, so some growers will opt for a border that does not look quite so full, by planting the peonies at 3 to 4 feet apart.
Peonies planted a greater distance apart will have the benefit of better airflow, though the resulting look may be too sparse for some gardeners. The best advice is to plant the peonies the same distance apart as the expected spread. For a peony that is expected to grow to between 2 and 3 feet in width, then 2.5 feet between each plant will work well.
How Deep Should Peonies be Planted?
Peonies should not be planted deep in the soil, because this results in an overgrowth of foliage at the expense of the flowers. For this reason, many growers recommend planting peonies at a shallow depth in the soil. You can determine exactly where in the soil your peonies should be planted by locating the eyes or buds on the root.
The eye should be planted at 2 inches below soil level. If the peony is planted deeper than this, you risk an underproduction of flowers, however, if it is planted more shallowly than this, then the roots won’t be well insulated against cold temperatures, and they may struggle to survive the winter. Getting the right balance between too deep and too shallow is essential, and this is known to be 2 inches below ground level.
When to Plant Peonies
Peonies are typically planted in the fall because this allows their root systems to become established before their growth period the following spring. If you live in a warm climate then continuing to plant peonies in the fall is the best option. This allows the roots to develop and become strong before they face high temperatures the following summer.
For gardeners in cooler climates, you can plant peonies in spring or fall with good results. If your climate hovers in the middle of cool and warm, you can experiment by planting some peonies in spring and some in fall, and observing which plants fare the best. Witnessing your plant’s response is the best way to figure out if they are happy with the way they have been treated, and you can adapt your methods accordingly in the future.