Remember that "color blindness" is not the complete absence of color. That is called Achromatopsia and it is only seen in 1 in every 33,000 people. What humans typically suffer from is a deficiency in the development of the cones in the eyes, making it difficult to decipher differences in colors such as red and green, or blue and green.
As mentioned above, patterns are a great way to separate different items visually. However, too many patterns will create a lot of noise. This noise has the potential to negatively impact the user experience by making the comprehension time longer, rather than making it shorter. A good rule of thumb is that if you consider the elements to have "too much color" in an area, it would also be "too many patterns".
This being said, of course, we're still left trying to decide how to make this EASIER to understand (IE: Faster to comprehend). So... let's start by figuring out exactly what we need.
1. Multiple, sizeable areas to denote different activities.
2. Visible separation of these activities so users can scan and comprehend their subject / meaning within 800MS (.8 seconds).
Ok, well let's consider these areas will probably be rectangular in shape. Also, we CAN have tool-tips as it is a desktop application, however; it's a realistic expectation that tool-tips or other added "features" are erroneous items and that the information could be better delivered in another way.
Ok, with shape in mind it's easier to employ the Gestalt Principles in order to better group the activities to make it easy to mentally scan the information. Ok, understanding that, let's see what we can do with these clusters of information.
- Utilize contrast to denote different activities (useful whether greyscale or not). Contrast should have a 15% increase or decrease in brightness between items. This is because if it is less than 10% difference in brightness, those with color deficiencies will have a more difficult time scanning.
- Utilize spacing to denote different activities. This also gives items
more breathing room to help it look cleaner (if done correctly). This
may be more difficult to utilize since you have columns of time to
show which time the activity occurs.
- Law of Common Fate may be very helpful here. You may be able to
utilize this psychology principle to help denote either the time of
which the activity occurs or "Place 1", "Place 2" etc as you have it
on your current mock up. (IE: You can have the groupings create
perceived lines, instead of actually "showing" lines here.)
I could go on forever but instead, I'll close with a few more items to keep in mind as you wireframe or mock up your new version:
The Law of Good Gestalt and Law of Past Experience are very helpful. IE: Take out anything that doesn't HAVE to be there or that is over complicated (IE: Tooltips). Also, look at pre-existing items in every day life that have the same function and figure out WHY they work and how people utilize them effectively (or why they AREN'T effective).
Lastly, if your new project doesn't work in greyscale it won't work in color. I hear a lot of push back against that guideline but it is used by the best logo designers (which is where I learned it) and I have successfully utilized it in Level Design (for 16-bit games), logo creation, pixel art and web design. I've never had that simple guideline not hold true.
Anyway, best of luck in your endeavor and I hope this answer was helpful.