University of Vermont Extension System
Department of Plant and Soil Science

Commercial Ornamental Horticulture (COH) Leaflet 18

Herbaceous Perennial Production

Leonard P. Perry, Extension Associate Professor

Field or Greenhouse?

Unless a specialty nursery, or firm with perennials as a low percentage, most growers utilize some of both. The choice depends on other business decisions (other crops produced, other items marketed). Half the growers in northern New England that grow in greenhouses, use under 1000sqft. Field producers vary by state from under one acre (ME), to 1-5 acres (VT).

Propagation (precautions):

*tissue culture-- only few species available, may get mutations

*seed-- inexpensive, not all species, may not come true

*vegetative-- best for many species, more labor and costly, need propagation area


*depends on market factors, business decisions (see more on marketing leaflet)

Pot culture:

*perennials can be more "forgiving"--not as fussy--as other florist crops

*often grown in cells or plugs, then transplanted to larger sizes

*unless propagating, hoop houses often used, uncovered in summer or with shade

*hand water, drip tubes (pots), overhead (most common), subsurface

*fertigation, slow release

*conveyors, monorails used to move indoors, field carts outdoors

Field culture:

*small areas/operations often use raised beds, hand cultivation and water

*medium operations often grow in rows, small equipment or hand cultivation, soaker hose or overhead

*large operations grow in rows in blocks, tractor cultivation, overhead water or trough

*fertility: compost, preplant and sidedress

*hand dug unless large (tractor eg potato digger)


*generally not--sold when dug or first year, or overwintered

Overwintering (pots):

*cool greenhouse with heat backup best, can control growth, use one or two layers of poly with outer one white, may cover flats inside with porous felt

*coldframe traditional, for small operations, may insulate or tap greenhouse heat, may consist of metal hoops to create mini-greenhouse or tunnel

*cover pots directly with sheet foam (white reflective surface) or "sandwich" of poly/straw/poly--outer poly white, use mice bait, may use fungicide drench prior


see pest references


The best is none. Herbicides often can't distinguish between weeds and perennials. Even if they work, the may affect growth of perennials such as rooting of cuttings. Even the safest of herbicides may kill 1/4 to 1/3 of species in mixed plantings. Directed applications of contact herbicides such as systemic Roundup is common. Best: hand pulling in pots, using a "clean" mix, or surface cultivation in field (mulches usually used if small area).


see marketing leaflet

Scheduling Options:

For Spring Pack Sales:

*April-- buy prefinished or as plugs

*Jan/Mar-- sow seed direct

*Feb/Mar--sow seed into plugs

Mar/Apr--transplant into packs

For Pot Sales:

*summer--divide stock, pot (qt-gal+ for landscapes)

winter--overwinter (see above)

*spring--pot bare root, seedlings, divisions grown or purchased (3-4", qt)

*Jun/Jul--sow seed



Return to Perry's Perennial Commercial Page

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. Lawrence Forcier, Director, UVM Extension System, Burlington, Vermont. University of Vermont Extension System and U.S. Department of Agriculture cooperating, offer education and employment to everyone, without regard to race, color, national origin, sex, religion, age, disability, political beliefs, and marital or familial status.