July, 2026 DLI Report
Welcome to the Vineland DLI report for July 2026. What a month it has been with lingering smoke from wildfires up in Northern Ontario and hurricane’s worth of rain in the Niagara region! How will these weather events effect the DLI levels from this past month? Read on to find out more!
In July 2026, Vineland received 4% more than in June 2026.
Read more: July, 2026 DLI ReportOnly looking for certain information? Use the table of contents to navigate between sections:
Data Summary – Vineland & Leamington
DLI data were available for most of July for Vineland. The average DLI for the month of July for Vineland was 51 moles/m2/day. The maximum DLI was 68.3 recorded on July 12th, and the minimum DLI was 15.4 recorded on July 15th.
DLI data were available for the second and third week of July for Leamington-Kingsville. The average DLI for the month of July 2026 for Leamington-Kingsville was 57.2 moles/m2/day. The maximum DLI was 73.7 recorded on July 12th, and the minimum DLI was 40.9 recorded on July 17th.
Leamington-Kingsville received 7% less light in July than June. The monthly DLI average for July 2026 is 5% lower than it was in July 2025.
Vineland received 4% more light in July than June. Leamington-Kingsville received 12% more light than Vineland.
Monthly Radio Report
Tune in on the second Tuesday of each month at 12:00 pm during the Noon Farm Show on CFCO Country 92.9, covering Windsor to Woodstock. Not in the area? You can listen live online at country929.com.
Background
We mounted a daily light integral (DLI) meter on the border of Leamington and Kingsville, Ontario, in 2024, and another DLI meter at the Vineland Research and Innovation Centre (VRIC) in Vineland, Ontario, in 2025 to give greenhouse producers in those areas access to readily available light data.
The details of the Vineland data are available on this blog. If you are interested in the Leamington Kingsville data, you can download the excel sheet at the bottom of this post.
Daily light integral (DLI) and photosynthetic photon flux density (PPFD) data are important to greenhouse production because they measure the amount of light that is available to the crop. This data can be used to adjust the growing environment, such as irrigation and carbon dioxide levels, to optimize photosynthesis and crop yield.
DLI is the total amount of light within the photosynthetically active radiation (PAR) spectrum (light wavelengths of 400-700 nm) that impacts a surface in a day. It is measured in moles per metre squared per day (mol/m2/day).
PPFD is the total amount of light within the PAR spectrum that impacts a surface every second. It is measured in micromoles per metre squared per second (µmol/m2/second).
The data provided here reflects the amount of outdoor light. The amount of light that greenhouse crops receive inside a greenhouse can be significantly lower (90-50%) and is affected by the cover material (clear glass, diffused glass, single polyethylene, double polyethylene, triple polyethylene, etc.), cover material treatment (whitewash), and curtains (shade, energy, blackout, etc.). The ideal DLI inside a greenhouse is different for each crop.
Objectives
The DLI and PPFD Data section of this blog provides greenhouse producers in southwestern Ontario and Niagara Region with outdoor light levels on a regular basis year-round. It is meant to serve as a record of the amount of light these locations received on a daily basis throughout the year.
Each blog post in this section contains tables with the available data for a one-month period and an Excel file with data from previous months.
NOTE: This data is provided for information purposes and does not represent the amount of light at other locations.
Materials and Methods
The data was collected using DLI-600 sensors from Apogee Instruments. They measured the extended PAR (ePAR) spectrum (400-760 nm), which includes far red light. The sensors were placed 90 cm off the ground outside of a greenhouse at the Leamington-Kingsville border and at VRIC in Vineland, Ontario.
When possible, a NanoLambda light meter was also used to measure irradiance (W/m2 for light in the 340-1010 nm spectrum range) and PPFD (µmol/m2/second for light in the 400-700 nm spectrum range) at a specific date and time. It was placed beside the Apogee light meter when measurements were taken.
Available DLI data is presented for each month in Figure 1 and Table 1, for each week in Figure 2 and for each day (24 hr period) of the current month in Figure 3 and Table 2. It is all available to download in the attached Excel sheet in the last section.
DLI Data
Figure 1: Monthly DLI data for Vineland is presented in 2 two graphs. Graph A) represents the average monthly DLI ± standard deviation. Graph B) represents the median monthly DLI and variability in the data using two ranges: the interquartile range (middle 50%) and the outer range (80% of data).
A)
B)
Table 1: 2025 and 2026 monthly DLI data for Leamington-Kingsville and Vineland. NA = not available.
Figure 2: Available weekly DLI data for Vineland in 2025, and 2026. Week 1 = January 1-7, week 2 = January 8-14,…,week 52 = December 24-31.
Figure 3: June 2026, daily (24 hr period) DLI data for Vineland.
Table 2: June 2026, daily (24 hr period) DLI data for Vineland.
| Date (day/month/year) | DLI (mol/m2/day) |
| 01-Jul-26 | 59.2 |
| 02-Jul-26 | 29.3 |
| 03-Jul-26 | 46.6 |
| 04-Jul-26 | 31.4 |
| 05-Jul-26 | 35.0 |
| 06-Jul-26 | 29.7 |
| 07-Jul-26 | 61.8 |
| 08-Jul-26 | 66.8 |
| 09-Jul-26 | 41.9 |
| 10-Jul-26 | 62.0 |
| 11-Jul-26 | 67.8 |
| 12-Jul-26 | 68.3 (Max for July, 2026) |
| 13-Jul-26 | 66.5 |
| 14-Jul-26 | 65.4 |
| 15-Jul-26 | 15.4 (Min of July, 2026) |
| 16-Jul-26 | 43.6 |
| 17-Jul-26 | 52.3 |
| 18-Jul-26 | 26.7 |
| 19-Jul-26 | 67.6 |
| 20-Jul-26 | 61.4 |
| 21-Jul-26 | 19.9 |
| 22-Jul-26 | 54.0 |
| 23-Jul-26 | 66.5 |
| 28-Jul-26 | 48.0 |
| 29-Jul-26 | 60.4 |
| 30-Jul-26 | 66.4 |
| 31-Jul-26 | 63.3 |
| July 2026, DLI average ± Standard Deviation | 51.0 (±16.7) |
DLI and PPFD data Excel Sheet
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