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HERBACEOUS ORNAMENTALS -PERENNIALS, ANNUALS AND BULBS |
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KEY CONCEPTS
I. General Discussion of Perennials, Annuals and Bulbs
II. General Cultural Requirements of Perennials, Annuals and Bulbs
- Site
- Sun
- Soil and drainage
- Selection
- Hardiness
- Growing from seed vs. purchased plants
- Planting
- Watering
III. Perennials
IV. Annuals
V. Bulbs
Return to Introduction
GENERAL CULTURAL REQUIREMENTS OF PERENNIALS, ANNUALS AND BULBS
Cultural requirements of site, site preparation, soil, drainage, selection, growing from seed vs. transplants, and care are generally the same for perennials, annuals and bulbs. Any special requirements will be addressed under each grouping.
Because there is a perennial, annual or bulb for almost every type of site, study existing conditions and choose the right plant for the site. Some plants may not bloom or may even die if the site does not match their cultural requirements. Use reliable reference books to determine the cultural requirements of each species. Knowing cultural and site requirements also can prevent unnecessary use of chemicals on plants misdiagnosed as "sick."
The following definitions explain what is meant by SUNNY, PART SHADE, and SHADE LOCATIONS.
Sun: at least 6 hours or more of full sunlight
Part shade: 1/2 day of sun, such as morning sun and afternoon shade. It also refers to lightly filtered sun through high tree branches.
Shade: north-facing beds shaded by structures; woodlands with minimal direct sun exposure
There are perennials, annuals and bulbs that will grow in each of these situations.
Most perennials, annuals and bulbs grow best in a loose, well-drained, moderately fertile loam with adequate moisture. Soils that drain poorly, especially in winter, can cause the crowns to rot, resulting in death of many otherwise hardy perennials. Poorly drained soils also will threaten the health of most bulbs.
The pH range for perennials is from 6.2 to 6.7, annuals from 6.3 to 6.7, and bulbs from 6.0 to 7.0.
Clay soils may need to be amended with organic matter to improve aeration and drainage. Add needed amendments according to soil test recommendations. A general rule for adding organic matter is to add 1 part organic matter to 3 parts native soil by volume.
If drainage is poor, but the gardener wants to grow selections that require good drainage, consider raised beds. Species that grow in moist or wet sites are additional options.
Fact Sheet 1242 lists perennials for specific sites, Reference Herbac.1. A list of annuals for special sites is provided in Fact Sheet 1223, Reference Herbac.2.
Ideally, test the soil and prepare new beds in the fall for planting the following spring. However, new beds can be prepared in spring. It may take longer to obtain soil test results from the lab during the busy spring season. Allow at least two weeks for newly worked soil to settle before planting. If soil is not allowed to settle, crowns of new plants may become exposed, threatening plant health.
Perennial weed control is essential in a new perennial flower bed. Controlling weeds is easier when done prior to planting the bed. Fact Sheet 1107, Reference Herbac.3, provides tips on weed control in the flower bed.
Work or till soil to a depth of 18 to 24 inches for new perennial plantings, 8 inches for annuals, and 12 inches for bulbs. Rock garden varieties or other shallow-rooted selections require only a few inches of prepared soil, but the site must be well drained.
Flower gardeners often have favorites. Favorite plants that are not appropriate for the site will require site modification or an alternative selection. When selecting, consider plant shape, such as column-shaped varieties, "roundy-moundies" or horizontally creeping types. Consider plant height, spread, leaf texture, form and color. Purchase plants or seeds from reputable nurseries that guarantee disease-free, named varieties. Larger sized, more mature plants will usually cost more.
Ohio gardeners should choose perennials and hardy bulbs labeled hardy for their Zone. These Zones are:
Arnold Arboretum USDA
Northern Ohio - Zone 4 Zone 5
Lake Erie Shore Zone 5 Zone 6
Central Ohio Zone 5 Zone 6
Southern Ohio Zone 6 Zone 6
Some perennials and bulbs listed for Zone 6 may survive in Zone 5 if grown in well-drained soil and heavily mulched for winter protection.
Annuals are not affected by winter hardiness. The last frost in spring affects planting dates and the first frost in fall ends the season for most annuals. The following maps provide a guide to these dates.
[illus. frost dates for Ohio from Ohio Gardening Calendar]
GROWING FROM SEED VS. PURCHASED PLANTS
Perennials, annuals and bulbs can be purchased in several forms: seeds; dormant, bare-rooted plants; rooted plants in pots of various sizes; dormant bulbs and pot-grown bulbs. Many perennials can be grown from seed, but they are more often purchased as transplants. Annuals are even easier to grow from seed, but most gardeners choose to purchase transplants. Bulbs are usually sold in a dormant state.
Mail-order nurseries ship dormant plants, growing plants, and bulbs at the correct planting time in your area. If you cannot immediately plant new stock, bare-root plants can be HEELED IN to a protected section of the garden. They also can be potted up and grown in a cold frame.
Plant bare-root and potted plants in a hole large enough to allow spreading out of the root system. Soak the roots of bare-rooted plants in a bucket of water for 1/2 hour just before planting. Plant at the same depth as they originally grew. Look for the original soil line on the plant.
When selecting transplants, choose those with dark green leaves, sturdy stems and side branches. Roots should be abundant, but not pot-bound. Plant immediately if possible. If transplants must be held, store in a shady area and water as needed.
Plants should be spaced a distance equal to their mature width. Ten-inch plants should be planted 10 inches apart. Clusters of 3 or more large plants or 5 or more small plants of the same color usually make a better visual impact than those planted singly.
Dig a hole that allows transplants to be at the same soil level as in the container. Loosen and spread roots to encourage new outward root development. Water immediately after planting.
Fertilize based on soil test results. Use either a time-released fertilizer that will last all season or plan to apply water-soluble fertilizer two or three times during the growing season. Liquid 20-20-20 or 23-19-17 formulations should be applied biweekly to annuals. Follow product instructions for dilution rates.
Gardeners who grow their plants from seed will notice the wide difference in seed size. Some seeds are so small that they should be mixed with sand before sowing. This allows better control over spacing. Seed companies offer some very fine seed in PELLETIZED form. Plants that have very small, dust-like seeds are often purchased as transplants because of the difficulty in handling these seeds.
Follow the steps outlined in Chapter 5 on Plant Propagation to grow most perennials and annuals from seed. Seed packets should provide essential information for germination and any special treatment of seedlings. Seeds can be started outdoors directly in a bed or in some protected area like a cold frame.
Apply water when soil becomes dry. Newly planted transplants quickly wilt if conditions are dry and windy. Water young and newly planted plants more frequently than mature, established plants. Keep soil moist to a depth of 4 to 5 inches. If rainfall does not provide this moisture, apply water at a rate of 1 inch per week. Try to keep water off foliage. A 2-inch layer of mulch that does not touch the crown of the plant will help conserve moisture. A new layer of mulch may be applied each spring after the soil warms to maintain a 2-inch depth of mulch.
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