Four Star Culture Guide - 2019 - 90

ROSA
(Rose)

ZONE HARDINESS
3 - 9 Oso Easy® Paprika, Hot Paprika®
4 - 9 Oso Easy Lemon Zest
5 - 9 Oso Easy Italian Ice®, Pink Cupcake,
At Last®, Urban Legend®
NUTRITION
pH: 5.6 - 6.2
EC: (2:1 extraction method) 0.9 - 2.0
Moderate to high fertilization is recommended.
150ppm - 300ppm N
TEMPERATURE for forcing from liners
Forcing/Growing on: 65 F Night - 72 F Day
Holding: 40 F Night - 50 F Day
Once plants reach a saleable size, they can be moved to a frost
protected open environment with good air movement.
WATERING
Moderate to moist: Water thoroughly without over-saturating.
Keep moist but not wet throughout entire growth cycle.
TIMING
28 Liner to True 1 Gallon: 10 - 12 weeks with one plug per
container. A typical planting date for spring forcing would be
Week 8 for finishing in Weeks 18 - 20. If a larger size is desired,
we recommend planting them in the fall and doing additional
bulking prior to dormancy. Planting a 28 count liner into a 2 - 3
gallon container and bulking in the summer is also a great way
to finish a larger, high-quality spring crop.
Quick Turn™ Liner to True 1 Gallon: 5 - 7 weeks with one
plug per container. A typical planting date for spring forcing
would be Week 10 for finishing in Week 18. Planting a Quick
Turn in Week 20 for finishing in Week 25 is also very achievable
on Oso Easy varieties.
Quick Turn Liner to 2 - 3 Gallon: Planting a Quick Turn liner
into a 2 - 3 gallon container and bulking in the fall is a great
way to finish a larger, high-quality spring crop.
VERNALIZATION
Roses are cold beneficial, meaning they do not require
vernalization for flowering. However, they will have a better,
stronger flush of flowers in the spring after breaking dormancy
if they have had a cold treatment.

PLANTING
Roses perform best when planted in a well-drained, porous
growing medium.
When growing shrubs, we recommend using an aged or
composted pine bark-based media as opposed to annual
growing mixes that traditionally tend to be heavier in peat. Bark
adds weight and stability to the growing mix and tends not to
compress and shrink over time, thus adding the longevity that
can be needed on long-term crops such as shrubs.
LIGHT/LIGHTING
Roses are day-length neutral and do not require long days for
flowering and forcing.
During early spring forcing, plants should be given as much light
as possible. Plants should be spaced such that they do not shade
each other. Unspaced plants can stretch, require additional
pruning and lead to an undesirable look on the retail bench.
TRIMMING/PINCHING
Pinching is usually needed on Roses several times during
production. Beginning in the early spring, Roses will send
out 2 - 3 dominant shoots that can cause the plant to look
nonuniform. Pinch these wild shoots before they get too tall.
Additional light trimming can and should be done throughout
growing to ensure good form, but flowering will be delayed if
too many terminals are trimmed. Roses can be trimmed hard
and will reflush in the late spring and summer for staging
multiple finished weeks. The successive flushes of color usually
will not be as strong as the initial flush of color following
dormancy.
GROWTH REGULATORS
Trimming and pruning is used mostly on Roses to control
plant height. However, spray applications of 30ppm Bonzi®
(paclobutrazol) seem to help in controlling height. Multiple
applications may be needed in the spring. When growing in
the greenhouse in spring, growth regulator treatments may be
preferred, as manual pruning removes valuable buds. Cultural
practices such as good air movement in an open environment
can also help control plant height and assist in finishing a
high-quality crop.

Four Star Greenhouse I www.pwfourstar.com I 734-654-6420
90

The rates and chemicals listed are based on our southeast Michigan growing conditions, and are not recommended for nationwide application.
Please adjust the rates and spray applications to your location and facility.

http://www.pwfourstar.com

Four Star Culture Guide - 2019

Table of Contents for the Digital Edition of Four Star Culture Guide - 2019