Nature Planting Signals for Vegetables: Phenology

The flowering of trees, shrubs, and perennial plants is determined by day length and temperature (this also applies to the lifecycle of insects and animals.

You can use the bloom time of shrubs and trees to tell you when it is safe to plant vegetables in the garden. Look at blooming trees and shrubs in your garden or neighborhood as indicators of when it is safe to plant vegetables directly in the garden.

Keep a record of weather conditions in your garden. Note when trees and shrubs leaf out and bloom—record the date and soil temperature (leaf and bloom times are triggered by soil and air temperature). Do this for 3 or 4 years and you can make your own nature planting signals calendar for your garden.

The study of regular events in the lives of plants, animals, and insects is called phenology (from Greek words meaning “science of appearances.”) Plant and animal life cycles are predictors of reoccurring events in nature.

Here is the lilac planting calendar for the vegetable garden:

• Lilac begins to leaf out: direct sow seed of cool-weather vegetables such as peas, lettuce, and spinach; direct sow cold-tolerant herbs such as parsley and chervil; direct sow hardy annuals such as calendula and sweet alyssum.
• Lilac flower spike is in full bloom: direct sow seed of basil, corn, and tomatoes; direct sow marigolds and geraniums.

Nature Cycles and Vegetable Garden Planting

Here are shrub and tree bloom times that can be used to signal vegetable seed sowing in your garden:

• Green Bean: direct sow when lilacs bloom.
• Broad Bean: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus in full bloom.
• Beet: direct sow when forsythia and dandelions begin to bloom.
• Broccoli: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus are in full bloom.
• Brussels Sprouts: direct sow when forsythia and dandelions begin to bloom.
• Carrot: direct sow when forsythia and dandelions begin to bloom.
• Cauliflower: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus are in full bloom.
• Celeriac: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus in full bloom.
• Celery: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus in full bloom.
• Chervil: direct sow when forsythia and dandelions begin to bloom.
• Corn: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.
• Corn Salad: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus are in full bloom.
• Cucumber: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.
• Endive and Escarole: direct sow when forsythia and dandelions begin to bloom.
• Eggplant: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Florence Fennel: direct sow when flowering quince, saucer magnolia, grape hyacinth, narcissus in full bloom.
• Kohlrabi: direct sow when forsythia and dandelions begin to bloom.
• Leek: direct sow when forsythia and dandelions begin to bloom.
  Lettuce: direct sow when forsythia and dandelions begin to bloom.
• Lima Bean, bush: direct sow when Chinese wisteria blooms.
• Lima Bean, pole: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Melon: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.
• New Zealand Spinach: direct sow when Chinese wisteria blooms.
• Okra: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Parsley: direct sow when forsythia and dandelions begin to bloom.
• Parsnip: direct sow when forsythia and dandelions begin to bloom.
• Pea: direct sow when forsythia and dandelions begin to bloom.
• Peppers: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Onion (sets, seed): direct sow when forsythia and dandelions begin to bloom.
• Potato: plant when daffodils and dandelions begin to bloom.
• Pumpkin: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.
• Radish: direct sow when forsythia and dandelions begin to bloom.
• Salsify: direct sow when forsythia and dandelions begin to bloom.
• Soybean: direct sow when Chinese wisteria is in bloom.
• Spinach: direct sow when forsythia and dandelions begin to bloom.
• Squash: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.
• Sweet Potato: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Swiss Chard: direct sow when forsythia and dandelions begin to bloom.
• Tomatillo: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Tomato: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Turnip: direct sow when forsythia and dandelions begin to bloom.
• Watermelon: set out plants when peony, black locust, and golden chain trees are in full bloom.
• Zucchini: direct sow when redbuds, flowering dogwoods, flowering crabapple in bloom, and lilacs are in full bloom.

Succession Plantings of Crops: Make succession plantings any time after the first planting dates but keep in mind the number of days for a crop to reach maturity and the increasing or decreasing air temperature as the season progresses; i.e. cool-weather crops must come to harvest before the warm temperatures arrive in late spring or summer and warm-weather crops must mature before cool and chilly temperatures arrive in autumn.

More tips at Spring Outdoor Seed Sowing Schedule and Vegetable Crop Planting and Phenology.