What to Plant With Asparagus: Asparagus Companion Plants (and What to Keep Away)

Asparagus is different from almost everything else in a vegetable garden. It is a perennial: you plant crowns once, wait two years for the first real harvest, and then pick spears every spring for many years. That changes how companion planting works. Asparagus does not move each year, so its companions are the annual crops and herbs you grow around or beside the bed, and the main rule is to avoid anything that means digging near its spreading crowns. This guide covers the extension-listed companions, what to keep away, and how to plant and harvest asparagus so the bed lasts.

Good companion plants for asparagus

Tomatoes

Virginia Extension lists asparagus and tomatoes as companions in both directions of its table, and it is one of the best-known asparagus pairings. The timing works: asparagus is harvested in spring, and tomatoes go out after the last frost, about when the asparagus harvest is winding down and the ferns start to grow. Plant tomatoes along the sunny edge of the asparagus bed or in the next bed rather than between the crowns, so you are not digging planting holes into asparagus roots, and leave room for the ferns, which grow several feet tall. You will see claims that tomatoes repel asparagus beetles; our extension sources do not test that, so treat it as a bonus if it happens. More in what to plant with tomatoes.

Basil and parsley

Virginia Extension lists basil and parsley as asparagus companions. Both are small, so they fit along the edge of an asparagus row without crowding it, and both are easy to plant without disturbing the crowns. Basil goes out after the last frost; parsley can go in earlier. Basil is also a classic tomato companion, so an asparagus row, a strip of herbs and a tomato row make a natural group. See what to plant with basil. More in what to plant with parsley.

What not to plant with asparagus

Virginia Extension lists onions, garlic and potatoes as incompatible with asparagus without giving a reason for each. There is a practical one they share: all three are crops you dig up. UMN Extension notes that asparagus has a deep root system, that rows should be at least 3 feet apart because the plants spread as they age, and that any cultivation in the bed should stay less than 2 inches deep. Digging potatoes or lifting onion and garlic bulbs next to the crowns risks damaging them. Grow those crops in a separate bed; our onion, garlic and potato guides list better neighbors, and every pair to separate is in the keep-apart chart.

Choosing the spot

UMN Extension says an asparagus planting can last 15 years or more, so pick the spot carefully:

• Sun and drainage. A fertile, sunny, well-drained site with soil that still holds moisture. Avoid shallow soils and places where water pools after rain.
• No frost pocket. Late spring frosts can kill emerged spears, so avoid low-lying or exposed spots.
• North end of the garden. If the bed is part of a larger vegetable garden, UMN suggests the north end so the tall ferns do not shade other crops.
• Soil pH. Asparagus grows best at a pH of about 6.5 to 7.0 and does not tolerate very acidic soil. Have your soil tested before planting.

When and how to plant crowns

Most gardeners start asparagus from one-year-old crowns rather than seed. UMN Extension plants crowns between early May and early June in Minnesota; in general, plant in spring once the soil can be worked, and keep crowns cool and moist until they go in.

1. Dig a trench 6 to 12 inches deep.

   Shallower (6 to 8 inches) in heavy clay, deeper (10 to 12 inches) in very sandy soil. Keep the soil you remove beside the trench.

2. Set crowns about 12 inches apart.

   UMN suggests laying them head-to-toe down the trench so the buds are about a foot apart. Space multiple rows at least 3 feet apart.

3. Cover with 2 to 3 inches of soil and water.

   Do not let the crowns dry out while they are in the trench.

4. Backfill gradually.

   Spears appear in two to three weeks. Once they are sturdy and several inches tall, add more of the saved soil, a few inches at a time, until the trench is level.

Annual companions such as tomatoes and basil follow their own timing. Our planting calendar shows when to start and plant them from your frost date.

Watering and weeds

UMN Extension recommends at least an inch of water a week, more often in sandy soil, because good soil moisture keeps roots and ferns healthy for next year's spears. Weeds are the bigger long-term problem in a perennial bed. Pull them by hand, especially around new crowns, and if you hoe, keep it very shallow and only before spears come up in spring or after harvest ends. Perennial weeds such as quackgrass and Canada thistle are the ones to catch early, because the bed is rarely tilled.

A simple asparagus bed with companions

1. Asparagus row along the north side.

   Crowns about 12 inches apart; the ferns will grow tall later in the season.

2. Parsley and basil along the south edge of the row.

   Listed asparagus companions that stay small and need no deep digging.

3. Tomatoes just to the south, after the last frost.

   A listed companion; give them their own space rather than planting between crowns.

4. Onions, garlic and potatoes in a different bed.

   Listed as incompatible, and all of them are dug at harvest.

Our raised bed layouts show how to map a bed by the square foot.

Harvest: be patient

UMN Extension advises no harvest in the first spring after planting crowns, so the plants can build strength. In the second spring, if the plants grew well, pick spears for about two weeks once they are 6 to 8 inches long, then let the rest grow into ferns. In later years the season lasts about six to eight weeks; UMN harvests until about the end of June in Minnesota. After that, let the ferns grow all summer, because they make the energy stored in the crowns for next year's spears.

Pests and problems

UMN Extension lists asparagus beetles, which scar spears and can make them bend into a shepherd's crook, and cutworms, which cut spears off at the base. Asparagus rust shows up as yellow and rusty orange spots on the ferns after harvest. Frost after spears emerge, or herbicide drift, can also make spears bend and curl.

Male and female plants

Asparagus plants are either male or female. UMN Extension notes that male plants tend to live longer and produce more, smaller spears, while female plants grow larger spears, form red inedible berries and can drop seeds that sprout as weedy seedlings. Most hybrids, such as Jersey Giant, have only male flowers. Either kind gives you edible spears.

Frequently asked questions

What grows well with asparagus?

Extension-listed companions for asparagus in our checker are basil, parsley and tomatoes. The table on this page explains why each pairing works.

What should you not plant with asparagus?

Our sources list garlic, onions and potatoes as poor neighbors for asparagus.