Growing instructions

Growing Instructions for Itoh and Herbaceous Peonies from Micropropagation

Itoh or  intersectional hybrid peonies are derived from crosses between herbaceous and tree peonies.  They thrive under the same conditions as herbaceous peonies.  They are best grown in the field or garden, but pots may be used for young plants (2 -3 years).  Tissue cultured peonies require 2 to 3 years to reach blooming size.  Itoh peonies are vigorous and it is important to leave them enough room to grow.

Location: All peonies do well in full sun, although flowers may last longer in partial shade.

Planting: If peonies are received in pots, they should be planted to the same depth as they were in the pots.  If plants are received bare root, they should be planted as soon as possible.  To ensure proper hydration, it is helpful to soak the roots in cool water for 15 to 20 minutes.  The proper planting depth is with the uppermost bud 1 inch (2.5 cm) below soil level.  A hole larger than the pot or roots should be prepared with compost mixed in a foot (30 cm) deep.  A spacing of 3 feet (90 cm) should be left between plants to allow growth to maturity.

Soil: The soil should be well draining.  Poor drainage leads to Botrytis, a fungal disease attacking the stem and shoots.

Irrigation/ Fertilization: Peonies are not fast growing so care should be taken not to overwater or overfertilize.  Any complete garden fertilizer not too rich in nitrogen may be used.  Fertilizer should be applied after peonies have bloomed (or after 1 month of growth for young plants).  Mature plants need very little care.

Dormancy and Winter Protection: Stems should be cut to just above ground level in the fall and destroyed to avoid disease carryover.  Most buds of Itoh varieties are found on the crown just under the soil as for herbaceous peonies, however some buds may be found on the lower parts of the stems.  These are not essential for growth and may be cut or left on the plant.  Although Itoh peonies are very winter hardy, mulching is recommended for young plants and in areas of insufficient snowfall.  Mulch should be removed in the spring to allow the new shoots to emerge.

Blooming: Itoh peonies will bloom in their third or fourth year from tissue culture.  First year blooms are often not typical of the variety; e.g. semi-doubles may be singles the first year, or doubles may be semi-double.  Second year blooms should be near normal, and the number of blooms will have doubled or more.  Itoh peonies have strong stems and plants do not need to be staked.

Diseases and Pests: Peonies are tough, strong-growing plants that exhibit excellent disease resistance.  The most serious peony disease is Botrytis or grey mould, which most often occurs during cold, wet springs.  All affected stems should be immediately cut and destroyed and pruning shears disinfected after use.  Good air circulation around plants, watering early in the day, and not watering the leaves all help to avoid disease problems.

Growing Instructions for Tree Peonies from Micropropagation

Tree peonies from in vitro culture are grown on their own roots.  In vitro cultured peonies require 3 to 4 years to reach blooming size.  They are best grown in the field or garden, but pots may be used for young plants (2 – 3 years).  Note:  they are not as vigorous as Itoh peonies.

 

Location: All peonies do well in full sun, although flowers may last longer in partial shade.

Planting: If peonies are received in pots, they should be planted to the same depth as they were in the pots.  If plants are received bare root, they should be planted as soon as possible.  To ensure proper hydration, it is helpful to soak the roots in cool water for 15 to 20 minutes.  Tree peonies from tissue culture are grown on their own roots.  Therefore, when planting, there is no graft union to take into consideration.

The proper planting depth is with the root system well covered and the lowest bud at soil level or slightly higher.  A hole larger than the pot or roots should be prepared with compost mixed in a foot (30 cm) deep.  A spacing of 3 feet (90 cm) should be left between plants to allow growth to maturity.

Soil: The soil should be well draining.  Poor drainage leads to Botrytis, a fungal disease attacking the stem and shoots.

Irrigation/ Fertilization: Peonies are not fast growing so care should be taken not to overwater or overfertilize.  Any complete garden fertilizer not too rich in nitrogen may be used.  Fertilizer should be applied after peonies have bloomed (or after 1 month of growth for young plants).  Mature plants need very little care.

Dormancy and Winter Protection: Tree peonies develop overwintering buds on lignified stems above ground.  Unlike herbaceous and Itoh peonies, stems must not be cut to the ground in the fall. In the fall, leaves and stems should be cut to just above a visible bud and destroyed to avoid disease carryover.  Tree peonies should be mulched and protected from wind in the winter.  Mulch should be removed in the spring to allow the new shoots to emerge.

Blooming: Tree peonies will bloom in their third or fourth year from tissue culture.  First year blooms are often not typical of the variety; e.g. semi-doubles may be singles the first year, or doubles may be semi-double.  Second year blooms should be near normal, and the number of blooms will have doubled or more.  Tree peonies have strong stems and plants do not need to be staked.

Diseases and Pests: Peonies are tough, strong-growing plants that exhibit excellent disease resistance.  The most serious peony disease is Botrytis or grey mould, which most often occurs during cold, wet springs.  All affected stems should be immediately cut and destroyed and pruning shears disinfected after use.  Good air circulation around plants, watering early in the day, and not watering the leaves all help to avoid disease problems.