Perennials are herbaceous plants that live for two seasons or more. For the vegetable and herb grower, perennial plants can save time and effort with great rewards. Though most perennial vegetables don’t survive frost or cold winters, there are a few hardy types that can withstand our Ohio winters.
When planting perennial vegetables and herbs, their placement should be thought of as permanent. Determine the best long-term place for them in the garden before planting.
Asparagus (Asparagus officinalis)
- Soil: Asparagus needs well-drained soil that has a pH of 6.5-7.5
- Plant selection: Choose only newer, mostly male hybrid varieties such as Jersey Giant, Jersey Prince, and Jersey Knight. The female varieties have smaller spears and will produce seeds that will become weeds.
- When to plant: Plant in early spring, in Ohio mid-April through late May, after the garden area has been worked.
- Planting: Plant a one-year-old disease free crown (the root system of the asparagus). Dig a trench roughly 6 inches deep by 15 inches wide and apply 1 pound of 0-46-0 fertilizer or 2 pounds 0-20-0 fertilizer for every 50 feet. Place the root crowns about 1 foot apart with the buds facing up and the roots spread out flat in the trench. Layer only 2 or 3 inches of soil back over the crowns and fill the space with water rather than filling it in with soil.
- Tips: Do not harvest asparagus during the first year; it is growing to produce food for the roots, so the plant needs time to become established. The second year, harvest just a few spears. During the third year harvest normally, but limit your harvesting time to just three weeks. Except in extreme cases, asparagus can be very drought tolerant because the roots seek water deep in the soil.
Rhubarb (Rheum rhabarbarum)
- Soil: Well-drained, loamy garden soil works great.Add organic compost to the garden before planting.
- Plant selection: Choose Canada Red, Cherry Red, MacDonald or Valentine for the best results. These varieties have redder stalks, and the redder they are, the sweeter they tend to be.
- When to Plant: Plant in early spring, waiting until the soil is dry enough to work.
- Planting: Plant the dormant root crowns 3 feet apart. Remember you need enough room for the leaves to comfortably grow. The buds need to be under about 1inch of soil.
- Tips: Only eat the stalks; the leaves contain poisonous substances. Remove the flower stalks, as they take a lot of energy to grow. It can take up to three to four years to get enough stalks for one rhubarb pie, but don’t be discouraged-good food sometimes takes time. Harvest (starting the second year) in the spring for about six weeks, when the stems are the size of celery stalks. Do not harvest all the stalks as the plant needs some leaves to stay alive.
Fresh herbs are a great way to add flavor to a homemade dish. If you wish to substitute dry herbs for fresh the exchange is as follows: fresh herbs to dry are 1 tablespoon fresh for every 1 teaspoon dried. The following is an easy list of the most commonly grown perennial herbs, or at least the ones I grow and use.
Chives (Allium schoenoprasum)
- Soil: Well-drained, loamy garden soil is suitable for chives.
- Plant Selection: Allium schoenoprasum is the Latin name for common chives while Allium tuberosum is for garlic chives, also known as Chinese chives. Both are tasty.
- When to Plant: Chives should be planted in the spring. They can be divided anytime during the rest of the growing season to produce more plants.
- Planting: Plant small potted plants or divided plants, spacing them 12 inches apart.
- Tips: As soon as new leaves start to appear, go ahead and start to harvest.Snip off leaves with a sharp pair of scissors. Discourage flowering as the leaves become tough and not as tasty. Also, the flowers will set and throw seeds about the garden.
Greek Oregano (Origanum vulgare ssp hirtum)
- Soil: Greek oregano likes well-drained soil; it also prefers soil that is not very fertile, so use less organic soil than in the rest of the garden.
- Plant Selection: Greek oregano is my preference, but many also like the Hot & Spicy variety.
- When to plant: Plant in the spring when the soil is workable.
- Planting: If you are growing more than one oregano plant, plant them 18 inches apart.
- Tips: In cooler areas of Ohio this plant will need a layer of straw for winter protection. As soon as the first flowers appear, it is time to harvest the leaves. Cut the top of the plant back to stimulate new leaf growth.
Thyme (Thymus vulgaris)
- Soil: For growing thyme, use sandy well-drained soil that is not very fertile.
- Plant Selection: Thyme comes in many scents and flavors, lemon, orange, nutmeg, coconut, so you are sure to find your favorite at the garden center.
- When to plant: Anytime in spring will be suitable for planting thyme.
- Planting: Plants should be at least 12 inches apart. Thyme does not grow very tall and can be best seen when planted close to the front edge of the bed or near the path.
- Tips: Water sparingly to avoid excess moisture. Using less fertilizer ensures the best taste. The flowers are edible too.
Keep in mind these are just a handful of perennial plants to grow in your vegetable and herb garden. Just remember to do your homework and read the tags to know what you’re growing and how best to care for and use it.
Barbara Arnold is green corps coordinator at Franklin Park Conservatory.