How to Enhance Pollination in Your Garden: A Complete Guide
The best way to ensure pollination is to increase the number of pollinators in your garden‚ to have blooms available when pollinators are active and to remove things that cause bees‚ butterflies and other bugs to avoid your plants at all costs‚ such as chemical pesticides and lack of nesting sites․ Following these tips in Tennessee (from late March to October‚ depending on your zone) will make the difference between a productive tomato and a beautiful tomato that produces almost nothing․
Tennessee falls mostly in the USDA zones 6b and 7b‚ so we have a relatively long season for pollinators․ But because the bees might not even get to the flowers before a freeze kills them in early spring‚ timing is everything․ If you can get the timing down‚ you're halfway there․
Reasons Why Pollinators Fail More Often Than Gardeners Know
Pollination problems are not due to lack of flower parts but to timing and/or lack of pollinator․ For instance‚ squash produces separate male and female flowers․ If there are not enough bees during the few hours of the day that the flowers are open‚ there will be plenty of flowers‚ but not many squash․ Similarly‚ an apple tree blooming on a cold and wet early April day may not get pollinated‚ because honeybees will not forage when temperatures are below 55 degrees Fahrenheit․
Most tomatoes and peppers are self-pollinated and can have pollen shaken out of them by wind or vibration․ Most fruit trees and other berries‚ as well as squash‚ melons and cucumber‚ are cross-pollinated and require pollen from a different plant transferred by insects․ If you know which plants in your garden are in which category‚ this tells you where to spend your effort․
Building a Garden That Pollinators Actually Want to Visit
One of the single best things you can do is to provide blooming flowers from early in the spring right up to frost․ If there is a period of six weeks in the middle of the summer where there are no blooms‚ pollination will probably be lost․ They won't come back right away․
A good bloom-succession for Tennessee gardens would include the following:
- Early spring (March-April): Creeping Phlox and early-blooming Coneflower varieties will attract pollinators when most vegetable flowers are not yet open․ - Late spring to summer (May to July): Coneflower‚ Bee Balm‚ and Black-Eyed Susan are the key flowering plants of this season and are preferred by native bees and butterflies․ - Late summer through fall (August - October): Asters and Goldenrod are more important than people realize‚ and often the last important nectar source before pollinators go into dormancy/migrate․
TN Nursery's perennial collections are planned with this kind of succession in mind; a mixed planting of Coneflower‚ Black-Eyed Susan‚ and native asters will give you pretty much continuous bloom across the growing season without you having to plan it flower-by-flower․
Bees tend to prefer open‚ flat flowers where the nectar and pollen are easily accessible‚ such as Coneflower and Yarrow․ Species such as Bee Balm and many native Salvia have tubular flowers which attract hummingbirds and some butterflies with long tongues․ A varied planting may attract more species than would a planting designed for honeybees․
Give Pollinators Somewhere to Live‚ Not Just Somewhere to Eat
For about 70% of native bee species that nest in the ground‚ leaving small patches of bare soil undisturbed (preferably under sunny‚ well-drained conditions) provides them with areas to burrow․ Alternatively‚ a small brush pile or a piece of dead wood in a back corner can provide a home for cavity-nesting insects such as mason bees․
More deliberately‚ a simple bee house made from hollow reeds or drilled blocks of wood can be provided for solitary bees․ These are less well known‚ but are better per bee than honeybees: on a per visit basis‚ a single mason bee does the work of about 100 honeybees‚ if only for the simple reason that they are somewhat less tidy‚ and visit many more flowers per hour․
Hand Pollination: When to Use It and How
You may have to do it yourself: with greenhouse-grown vegetables‚ for instance; or with early-season plantings before the pollinators are active; or with squash plantings in a particular year where the pollinators decide to ignore some flowers․ Hand pollination of squash and cucumber is easy: just brush pollen from the anther of a male flower onto the stigma of a female flower․ Do it early in the day‚ while the flowers are freshly opened․
Tomatoes need gentle pollination․ Shaking the plant or giving the flower stem a gentle thump with a fingertip breaks apart these pollen bundles‚ as would occur in the wind or as the flower is bombarded by a large bee․ Shake or thump your plants every few days while the fruit is forming‚ especially if you're growing in a greenhouse or other enclosed area without airflow․
Water‚ Fertilizer and Flower Quality
Under-watered or nutrient-stressed plants produce smaller and less nectar-rich flowers․ Pollinators notice․ Keep plants well watered‚ providing about 1 inch per week for flowering perennials and vegetables‚ instead of waiting for the soil to dry out and then drenching․ High nitrogen levels also encourage foliage growth at the expense of flowers‚ so applying a balanced fertilizer or preferably an N-deficient (phosphorus-leaning) fertilizer early in the bud-forming stage tends to increase flowering․
Skip Spraying during Flowering
This one gets overlooked constantly․ Even organic-approved insecticides like pyrethrins can kill visiting bees if they are applied when the flowers are open․ If a pesticide must be applied‚ spray in the evening after bees have finished foraging‚ and avoid spraying where the product drifts onto flowers․ Systemic pesticides‚ such as some neonicotinoids‚ stay in the pollen and nectar of treated flowers for weeks or more‚ so check the labels of systemics for use on or near flowering plants․
Putting It Together
However‚ none of these practices will work in isolation․ A garden with great pollinator plants but loaded with pesticides will still struggle to attract pollinators‚ and a pesticide-free garden that lacks flowers from June through August will still struggle․ The ones that get the best fruit set and the highest yields are the ones that treat pollination like a system that runs all season long‚ with overlapping bloom times‚ undisturbed nesting habitat‚ water and fertilizer supplied regularly‚ and hand pollination as a backup‚ not as a primary․
Start with the plants that are going to be pollinator magnets in your area first (Coneflower‚ Bee Balm and native asters are about as reliable as it gets in Tennessee gardens)․
