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Perennials & Shrubs — Choose Your Best Option

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Perennials and flowering shrubs are grabbing consumers’ attention, and many annuals growers are starting to grow them.  Here are some tips to help ensure that your plants are healthy and ready for market.

Large perennials and shrubs can benefit from vernalization and bulking over the winter, and grow better with adequate spacing and air movement in the greenhouse.


Perennial and shrub growers have a choice — either buy small plugs in late summer/early fall and do their own bulking and vernalization over the winter, or buy larger plugs for the spring and force them for market, says Dan Foster, Site Manager/Product Line Manager, who oversees growing of grasses, perennials and ColorChoice® shrubs at Four Star Greenhouse.

Both options have advantages. “If you do your own bulking and vernalization, you can get them rooted in and let them get big so you have a nicely sized plant at retail,” he says.  “If you have the time, the available labor, the space, and you’re looking for a more economical option, this could be a good fit for your operation.”

For growers who don’t grow this time of year or have other limitations, buying larger plugs is the other option, Foster explains.  “The bigger plugs would be a better option then, because the plugs already have the bulking, trimming, vernalization and insect treatments done.  Although they cost more, there is less work and less worry involved.”

If a grower is new to perennials and shrubs, this might be a better option. 

Large perennials and shrubs can benefit from vernalization and bulking over the winter, and grow better with adequate spacing and air movement in the greenhouse.

Six Best Practice Tips for Growers

Foster recommends six important steps for growing healthy, attractive perennials and shrubs:

1.  Select the correct plant for your growing area.  Use both the USDA Plant Hardiness Zone Map and the American Horticultural Society Plant Heat Zone Map to make sure the plants are suited for your growing area, as well as your customers’ areas.

2. Scout carefully and frequently.  Because these crops have a longer time in the greenhouse than annual crops, it is more important to have a regular and thorough program of scouting for insects, diseases, weeds and other long-term problems.  “Stay on top of weeds with perennials,” he stresses.  Scouting is an ongoing process at Four Star, with each range scouted weekly.

3.  Vernalize and bulk up for the best crops.  This process allows the roots and eyes to thicken, while the plants grow strong and sturdy, resulting in bigger, stronger plants with better flowering (and a more attractive appearance at retail).  “If these practices are new to you, it is worth your while to learn how to do it so you can produce better crops that sell for more money,” says Foster.

4. Give plants space and air movement.  While this is an important practice for annuals, it is an especially good practice for perennials and shrubs, which can grow quickly in the spring.  Plants can grow tall and leggy if they don’t have enough space – they’ll grow upwards.  Foster also finishes the perennials and shrubs in an open air area before shipping – usually in an open roof house – so they receive natural air movement and grow fuller, thicker, and healthier.

5.  Manage soil pH properly.  Long-term crops need growers to watch the soil pH through the whole cycle of growing – it’s as important for perennials and shrubs as it is for annuals.  “Have a monitoring system to check nutrition and pH or things can get out of whack,” Foster notes.  He tests shrubs weekly and recommends at least once a month checks.  “For example, if the pH is off, the Hydrangeas will not stay blue or Spirea could develop yellow foliage.”

6.  Use an appropriate soil mix.  While peat-based mixes are fine for annuals, perennials and shrubs need soil with more strength.  “Peat-based soils can shrink, and these plants need a stronger mix that offers longevity, stability, strength and weight,” says Foster.  His recommendation includes using a nursery-type mix with some bark mixed in for added strength.

Smart Marketing Increases Sales

As perennials and shrubs grow more popular, the industry is starting to rely more on branding to differentiate and add value, says Dan Foster of Four Star Greenhouse.  “We’re seeing more value added through containers and tags, as well as offering larger pots with larger plants.”  Branded plants offer the advantage of marketing support to build interest and demand with consumers. 

Fresh flowering shrubs and perennials sell better at retail.  Plants placed on the bench, like these Hydrangea, have even more appeal to women shoppers.

Another trend is to have flowering shrubs at retail earlier in the spring, as gifts, notes Amber Coch, Four Star’s Garden Ready Sales Supervisor.  “We had flowering shrubs in full bloom for the early spring sales and couldn’t keep them stocked.  If people saw flowers then, they bought them.”

Coch also recommends growers and retailers plan ahead to increase sales of perennials and shrubs by doing the following:

  • Make sure plants are in flower when they hit retail.  “Consumers want to touch, feel, and see what they’re getting,” she says.  “Foliage plants like Dolce® Heuchera, however, will sell because consumers can see what they get.  For Hydrangea, both pink and blue color means successful sales.  The same thing applies for Sambucus in bloom.”  
  • Fresh, quality plants are best.  “I’ve seen consumers time and time again walking around, comparing the shrubs, looking at the size and the stems to see which is the best quality,” Coch notes. 
  • Know your customer – women.  Most of the customers will be women, and they want to see things on a bench, not just on the ground.  “Give customers education on perennials and pruning shrubs.  If they see plants with fruit or flowers, they believe they can succeed in growing them.”
  • Fresh is always best.  Nothing says ‘stale’ better than an old, worn or cracked container or tag.  “Before plants go to market, take the time and effort to pot up in newer containers and make sure the old labels are replaced with new,” Coch adds.

For more information on growing Four Star’s perennials and shrubs, contact us at 734-654-6420 or

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