It’s that time of year – no, not Christmas, it's the time when the seed catalogs start coming in the mail! While you brainstorm next year’s plantings, consider growing asparagus and rhubarb. Because these perennials live for years, they are worth the time investment. They often provide the first garden harvest of the year. You may not even need to plant asparagus, as it grows wild in some places.
If you've never had fresh picked asparagus – steamed, stir fried, or even raw – you've missed how good asparagus can be. I would say the flavor is kind of like snap peas, but different in a good way. Here in northwest Wisconsin it grows wild in places, along fence lines and under power lines where birds plant the seeds after they eat the fruit during the summer. The mature plants are the easiest to spot along roads and walking sunny fence lines. You can map them out and then come back in the spring. This is what last year’s mature plants look like:
How to Grow Asparagus
The planting guidelines I’m sharing are adapted from the University of Wisconsin Extension.
Prepare the Planting Area
With any perennial you want to do a good job of preparing the planting area. Asparagus likes a pH of 6.5 to 7.0 so a soil test is recommended. Lime the soil (adding lime to increase the pH) if needed. Either smother the existing vegetation or till it under and clear new weeds that emerge. Work in a generous amount of organic material such as compost and apply a complete fertilizer such a 5-10-20 at a rate of 1 pound to 10 feet of row. Also apply nitrogen or a complete mixture with nitrogen at the end of the cutting season each year.
Plant Your Asparagus
Plant healthy, vigorous one year old asparagus crowns or transplants in the spring. Either use transplants or purchase one year old crowns. (Make sure you don't let your roots dry out.) Dig a 6 to 8 inch deep trench and place the crowns 18 to 24 inches apart in rows that are 3 feet apart. Cover with 2 inches of soil and fill in the remainder of the trench throughout the growing season. Be sure to plant asparagus on well-drained soil in a spot you don’t have to disturb, the plantings can last 15- 20 years if maintained. (Seeds may not grow true to type and would take a very long time to be ready to harvest.) For a discussion of which asparagus varieties may be best for your area, check out this Asparagus Production Manual.
Weed and Pest Control in Asparagus
For weed control, use shallow cultivation and mulching. Do not rotor till next to established plants you will damage the root system.
Slugs and asparagus beetles may want to dine on your asparagus. Watch for eggs and beetles, and hand pick them into a container of soapy water. Encouraging beneficial insects in the garden and other predators such as toads and frogs in the garden is also helpful. You can read more about asparagus beetles at the University of Minnesota Extension.
When to Harvest Asparagus
Harvest will not begin until the third growing season, when spears are well developed but the tips haven’t begun to open. Pick spears that are 6 to 8 inches tall and have the diameter the size of your index finger. Cut or break the spear near the soil. Avoid harvesting skinny woody spears. Usually the harvest last for about 2 weeks the first year, and increases by about a week each year until the harvest last six weeks. Stop harvesting when most of the spears are skinny. Remove mature plants in the fall after frost for sanitation purposes and to avoid problems with plant disease.
Once you've collected your spears, you may want to make up some cream of asparagus soup, or if you have a larger harvest, you may wish to preserve your asparagus using freezing, drying or lactofermenting.
How to Grow Rhubarb
Rhubarb or pie plant (top photo of post) is one of the first plants to produce in spring time, and can be used for both sweet and savory recipes. It freezes fairly well and can be used in different jams and preserves such as strawberry-rhubarb jam, rhubarb barbeque sauce and rhubarb-orange compote. Frozen rhubarb works well for making rhubarbade.
Prepare the Planting Area
As with asparagus, it's best to smother weeds/clear the area before planting. Because rhubarb grows more densely than asparagus, it has an easier time out-competing weeds once established, but you'll have a healthier, more productive patch if you clear the weeds. Before you set in new plants, work composted manure or other organic matter into the soil and apply at least 1 pound per 10 feet of row of a complete fertilizer such as 5-10-20.
Add extra nitrogen each year in early spring or after harvest. Rhubarb can tolerate a pH down to 5.0, but prefers a pH of 6.0 to 6.8. It is classified as a cool season perennial, and needs winter temperatures below 40F/5C and growing season temperatures less than 75F/24C. (Sorry southern readers!)
Plant Your Rhubarb
To start a rhubarb planting, you can buy plants or lift and separate healthy, established plants before new growth starts in early spring. Cut the old plants into healthy pieces of root with one or more large, vigorous buds. Replant these in well drained soil in a new location. The buds should be planted 4 to 6 inches deep and spaced 2 feet apart in rows 3 feet apart. (As with asparagus, seeds may not grow true to type and would take a very long time to be ready to harvest.)
When to Harvest Rhubarb
Begin harvesting rhubarb the second season after planting. Pull leaf stalks upward and to one side or cut them. Harvest may extend through spring and into early summer. Harvest for freezing or canning in early spring when the leaf stalks have maximum color, flavor and tenderness. Leaves can be used as mulch for the plants. If damaged by frost, stalks can still be used if firm and upright.
Special Considerations for Rhubarb
Rhubarb should be relocated every 6 to 8 years according to the book, but I have a planting that is still holding its own after 30 years. Good care goes a long way towards crop health.
To extend the season, plant some of your rhubarb in partial shade. It will start growing later in the season but will stay tender a month after plantings in full sun have gotten woody and tough.
Don’t forget to get some water to the plants during harvest time. The rhubarb plants them self are deep rooted and will survive but the stalks will be tough without enough water.
WARNING: do not eat the leaves of the plant, eat only the stalks. The broad green leaves contain large amounts soluble oxalates and are poisonous. The stalks contain harmless malic acid.
There you have it – the basics of growing asparagus and rhubarb. It takes a bit of an investment of time but you will be rewarded for years to come!
This is a guest post written by my brother, Richard Poplawski, who gardens in northwest Wisconsin.