Phenology is, basically, the practice of observing nature and letting those observations tell you when you should accomplish certain tasks. Phenology looks at everything: plant growth, bloom time, blossom drop, appearance of different insects, animal migration times, and translates that into a timetable for you. It is known as "the science of appearance," because it is based on when certain things first appear each year.
Phenology is not fool-proof. Much like companion planting, the evidence is anecdotal. But much of the advice has been followed for hundreds of years, and it makes it easy to remember when to do certain things in your garden. Anything that simplifies gardening is worth a try!
Phenology for Your Vegetable Garden
Phenology is very useful in helping us figure out when to plant certain vegetables in the garden. We look at bloom times and leaves of other plants to let us know when the ambient temperature or soil temperature is right for planting. Here are some of the most common phenology tips for vegetable gardening.
When the shadbush is in bloom, plant potatoes in the garden.
Plant hardy crops in your garden when plum and peach trees are in full bloom.
It's time to plant tomato plants in your garden when Lily of the Valley is blooming. Other advice states to plant them when daylilies start to bloom.
Plant peppers when bearded irises are in bloom.
Plant eggplant when bearded irises are in bloom.
Plant cabbage when mockorange is in full bloom.
Plant peas when the daffodils start blooming.
When the oak leaves are the size of a squirrel's ear, it's time to plant corn. Also, when apple blossoms start to fall.
You can plant beets in your garden when dandelions start blooming.
It's time to sow lettuce seeds when dandelions bloom.
Sow spinach seeds in your garden when dandelions start blooming.
Plant carrot seeds when you see dandelions in bloom.
Plant beans in your garden when the lilac is in full bloom.
Plant squash when the lilac blooms start to fade.
Plant cucumbers in your garden when lilac blooms start to fade.
Phenology for Your Flower Garden
You can also time the planting of your flower garden according to phenology. Here are some common phenology tips for annuals and perennials.
Prune your roses when the forsythia is in bloom.
Direct sow zinnia seeds when the black locust is in bloom.
Direct sow marigolds when the black locust is in bloom.
Plant perennials in your garden when the maples start to unfurl their leaves.
Direct sow morning glory seeds when the maple tree has full sized leaves.
Phenology for Your Lawn
There are a couple of useful phenology tips when it comes to lawn care, especially for fertilizing and weed control.
Fertilize the lawn when the forsythia are in bloom.
Crabgrass seed germinates when the lilac is in full bloom.
The best way to use phenology in your own garden is to keep a record (a simple notebook would suffice, or a spreadsheet if you're so inclined) of when certain things, such as forsythia bloom, lilac bloom, and other events happen in your garden. Then you can see, over a few years, whether the phenology tips above actually work in your garden. I've found most of them to be fairly accurate in my garden, at least most of the time. If nothing else, phenology is a great way to really experience the seasons and learn more about the plants in your garden.