Forcing Tulips in Winter: A Reading List
Forcing stems for Market
Start with the Cornell hydroponics primer from William Miller's lab, even if you have no intention of growing anything on water. About a third of the Dutch cut tulip crop is forced hydroponically, and the article walks the whole sequence: most of the cold given dry and unplanted, a short cold rooting period, then warmth.
Cornell, A Primer on Hydroponic Cut Tulips: http://hort.cornell.edu/bulb/trade_articles/Tulip%20hydroponics%20(WEB)%20(2).pdf
Cornell Flower Bulb Research Program newsletter: http://hort.cornell.edu/bulb/newsletter/pdfs/25-201011.pdf
Ednie / Ball Seed tulip cut flower catalog, for cultivar selection and forcing-group data: https://www.ballseed.com/PDF/Catalogs/TulipCutFlowerCatalog-2022-EdnieFlowerBulbs.pdf
VWS, Forcing Tulips on Water: https://www.vws-flowerbulbs.nl/assets/files/Teeltinfo/FORCING-TULIPS-ON-WATER.pdf
Ruigrok, Forcing Tulips: https://ruigrokflowerbulbs.com/wp-content/uploads/2020/04/Forcing-tulips.pdf
Timing a crop to a specific date
Forcing is mostly date math, which makes sense since most flower farming is date math. The bulb needs a fixed number of cold weeks, so you count backward from your sale date to know when cooling starts. Cut tulips want sixteen to twenty weeks of cold; potted ones want fourteen to sixteen. Valentine's Day has its own schedules, and the Netherland Bulb sheet and the AATCC review break the week counts out by how early you want bloom.
Netherland Bulb, Early and Valentine's Day Forcing: https://www.netherlandbulb.com/_ccLib/attachments/pages/Early+and+Valentine%27s+Day+Forcing.pdf
AATCC Review, Achieving Year-Round Bloom: A Comprehensive Review of Flower Bulb Forcing Methods: https://aatcc.peerjournals.net/wp-content/uploads/2024/09/Achieving-Year-Round-Bloom-A-Comprehensive-Review-of-Flower-Bulb-Forcing-Methods.pdf
Tulip chapter, plantgrower.org: http://www.plantgrower.org/uploads/6/5/5/4/65545169/tulip_chapter.pdf
North Carolina State, bulb forcing reference: https://hortscans.ces.ncsu.edu/uploads/f/o/forcing__538cd8e19667a.pdf
North Carolina State, tulip nutrition during forcing: https://hortscans.ces.ncsu.edu/uploads/n/u/nutritio_53e0fb8a5711b.pdf
The Fundamentals
These are the extension fact sheets written for gardeners who just want a bowl of tulips on the table by March. These guides will not get you far on commercial timing, but they are a better place to start if you are just beginning
Washington State University, Forcing Bulbs: https://s3.wp.wsu.edu/uploads/sites/2053/2012/11/67ForcingBulbs.pdf
Purdue, Forcing Bulbs for Indoor Bloom (HO-19): https://www.purdue.edu/hla/sites/yardandgarden/wp-content/uploads/sites/2/2016/10/HO-19.pdf
University of Missouri Extension, bulb forcing (G06550): https://extension.missouri.edu/media/wysiwyg/Extensiondata/Pub/pdf/agguides/hort/g06550.pdf
Kansas State, Coffey County, Forcing Bulbs: https://www.coffey.k-state.edu/lawn-garden/gardening/Forcing%20Bulbs.pdf
Mississippi State Extension (P2730): https://extension.msstate.edu/sites/default/files/document/2025-12/P2730_web_4.pdf
University of Kentucky Master Gardener, bulb forcing: https://publications.mgcafe.uky.edu/files/4be12po.pdf
Piedmont Master Gardeners, bulb forcing: https://piedmontmastergardeners.org/wp-content/uploads/2025/02/20191212_164709.316-dl-1.pdf
Little Green Thumbs, Forcing Spring Bulbs to Bloom: https://www.littlegreenthumbs.org/wp-content/uploads/2020/05/Forcing-Spring-bulbs-to-bloom.pdf
Bulb forcing reference (Squarespace-hosted): https://static1.squarespace.com/static/5aecd213f2e6b1a3c574cec3/t/6154d31f2b15c02451502799/1632949025700/Bulb+Forcing.pdf
Utah State Extension, Encouraging, Not Forcing, Bulbs: https://extension.usu.edu/yardandgarden/research/encouraging-not-forcing-bulbs.pdf