In the wildlife industry, there is a lot of miss information in regard to the topic of clipping your perennials. Here is some science behind perennial food plot maintenance. Every forage grows at different stages. Time of year and environmental factors affect rate of maturity. All forages go through stages. There is early vegetation, late vegetation, early bloom and full reproduction phases.
As a general rule of thumb, most perennials reach maturity around 60 days after planting. At that point, they will begin to bloom or blossom. This is where they will begin to produce seeds, which could be harvested or let go to repopulate. Once any forage is blossoming, the quality begins to plummete. Unless there are few available desirable forages nearby, deer will not consume much of these mature forages. Once forages reach maturity, when you clip them, they will take a bit longer to resume active growth.
Ideally, you should clip your clovers and perennials when 1/10-1/4 of them are blooming/blossoming. This allows the plots to maintain top quality, as well as encourage active regrowth. When you clip these forages, the old saying was "take half, leave half." This means to only remove 50% of the total plant height. Why we recommend this is, the more plant that is removed, the higher the chances of shutting down the plants roots. This slows down the plants ability to regrow. Plants grow by photosynthesis. You need plant surface area to capture the suns rays to recharge itself. A minimum of 6" of height should be left at all times.
Another consideration of clipping more often is you are putting less material back onto the ground. This reduces the chances of smothering or killing the forages that are still left. You also encourage a more rapid breakdown of the left over organic matter, for incorporation back into the soil. Whether you have a bush hog, lawn mower or weed eater, having a consistent and regular clipping of your perennials is required.
When to clip? Alfalfa grows and matures more rapidly than clovers. Ideally, we need to clip alfalfa every 28 days or so. For perennial clovers, they tend to mature at around 35 days. Note that during the spring flush, this could be a bit more often. Because of the cooler temperatures, in the fall, you might only need to clip every 35-42 days. The amount of heat units is a huge factor, as well as hours of daylight.
Should you ever let clovers blossom or head out? In my opinion, NEVER. The way to keep your perennial plots going year after year is to fertilize property by applying enough potassium every fall. This helps winterize your forages and improve plant root reserves. You should plan on applying 1-3 lbs of seed per acre per year by the means of frost seeding or over-seeding. This is relatively inexpensive and a better agronomically than leaving poor forages standing. With limited resources, why not have every plot on your property being as desirable and effectively growing as you can make them?