Strawberries are relatively simple little plants. Their genomes have been completely mapped, and their life cycles are fully understood. But, as simple as strawberry plants may seem, they are still complex enough to warrant study; and, the study that goes into them continues to reveal much fascinating information. This post is dedicated to that topic of plant fertilization that sometimes can induce somnambulism in all but the most ardent botanists: strawberry pollination. But, once you've reviewed this information, you'll be ready to tackle hand pollination of strawberries or be better able to situate your strawberry bed in the most ideal location for growing gargantuan berries!
Strawberry Pollination: Background
There is quite a bit of confusion surrounding what strawberries can and can't do when it comes to strawberry pollination. A bit of background information should help clear some of the muddled minds out there.
First of all, let's note what the recent research shows: strawberry pollination is good for plants. Sure, I know that is the way the plants roll, but in our hi-tech society, more and more means of manipulating living organisms in order to boost yields and support the calls for bigger barns are churned out annually. Lost among the latest man-made development is often the simple fact that nature often does it best.
When it comes to strawberries, the largest, plumpest, most colorful strawberries are actually the ones that were trod upon heavily by 6-legged chitin-covered creatures when they existed in their flower stage. The more heavily pollinated a strawberry is, the bigger and better the berry becomes.
Secondly, strawberry plants produce flowers that are hermaphroditic. That means each strawberry flower contains both the male stamen and the female pistil. Pollen from the stamens at the outer edge of the flowers must make it the short distance to the pistils in the center for any fruit to set. If a strawberry plant is grown completely undisturbed in a hermetically sealed apparatus with no wind or other movement, pollen wouldn't make it to the pistils, and there would be no strawberries.
Thirdly, however, is the fact that strawberry plants are frequently (and accurately) described as “self-fertile.” What that means is that if your strawberry plant has only one flower, pollen from the poor fellow will suffice to fertilize itself and form a berry, providing the pollen reaches the pistil.
How to Pollinate Strawberries
Remember, strawberry pollination is good. The more you have, the better your strawberry haul. Pollination makes larger and more numerous berries in virtually any strawberry bed. So, here is how to pollinate strawberries using three different methods.
1. Let the insects do the work for you.
This is actually the best method of strawberry pollination. Insects, especially bees, will find and pollinate strawberry flowers quite effectively. Planting your strawberry patch where it will receive the most attention from the creepy-crawly-flying thingies is a great idea. Remember, the more pollination that occurs, the bigger your strawberries and your overall yield. What is fascinating is that insect diversity actually matters. Domesticated honey bees will focus their fertilization on the top of the flower while wild species of bees typically fertilize more heavily around the base of the flower. Each fly or butterfly or beetle that comes sniffing around will also fertilize the strawberry (albeit less effectively) by spreading pollen around. In short, insect diversity matters. You want the biggest and best strawberries? Let the bugs flock forth to do their strawberry pollination.
2. Let the wind do it.
Even gentle breezes are sufficient to transfer the pollen a few millimeters from stamen to pistil. So, even in the absence of bugs (like an a hydroponic set up or a bug-free window sill), strawberry pollination can still occur. However, wind or breezes often won't do a great job. So, you will probably end up with fertilized strawberries (at least a few), but you might be disappointed with the overall haul.
3. You do it.
The tiny motes of pollen that can be found on the stamens of strawberry flowers are not picky. Being as small and light as they are, they are transferred around rather easily. Brushing the outer edge of flower with your finger (gently!) to move pollen into the center of the flower is an easy and quick way to pollinate your strawberries. More effective is using a fibrous or small-bristled utensil to brush/collect pollen from multiple flowers and “paint” them onto the pistils of multiple flowers. A makeup brush, fine-bristled paint brush, or a q-tip that has the cotton teased out on one end all will work. For a demonstration, see the following video:
Benefits of Strawberry Pollination
1. Heavy pollination increases the overall yield of strawberry plants.
2. Cross pollination leads to decreased deformations and an overall higher-quality aesthetic.
3. Cross pollination results in larger overall strawberries than self-pollination or same-variety pollination. Remember, insect diversity also matters. Get as many good bugs to visit your plants as possible!
4. Natural strawberry pollination increases commercial viability also. Bee pollination results in brighter and redder berries, which are more pleasing to customers. Natural pollination also improves quality by reducing spoilage. To quantify, studies show that bee pollination results in 39% greater value than wind pollination and a whopping 54% greater value than self-pollination.
How Does Pollinating Strawberries Make Them Better?
While it is observable and repeatable that strawberry pollination improves strawberry harvests (as well as affecting other fruits by increasing firmness (in melons and cucumbers) and sugar content (in a few other fruits)), the science behind it isn't fully understood as of yet. The most likely explanation for the dramatic beneficial effect that pollination of strawberries has is that it stimulates two major plant hormones, auxin and gibberellic acid. Gibberellic acid provides increased shelf-life by delaying softening of the accessory flesh of the strawberries (the red part). This assists berry longevity by reducing the bruising that strawberries so frequently suffer and diminishing susceptibility to mold. Auxin, on the other hand, increases cell division and growth. The result of auxin stimulation is increased weight and firmness of the fruit.
As to the reasons why pollination of strawberries affects their color, your guess is as good as anyone else's for the time being. The processes that are involved in the upregulation of the bioflavonoids that give strawberries their signature hue are unknown at present. It does make a sort of sense, however, that the prettiest fruits attract more animals that better disperse the seeds after consumption.
I'd have to admit that I'd go for the biggest, brightest strawberries first myself! Hooray for strawberry pollination!