This is a good time of year to plan and make preparations for planting new perennial crops. As well as the better known fruits, options include rhubarb (also known as pie plant) and asparagus. Both are early harvesting crops, so can provide fresh produce to start your CSA season or enhance your market booth or your offerings for restaurants. Rhubarb can also be used in jam-making, for those looking for value-added products to extend the market season. Rhubarb is better known among older people, so supplying recipe cards and samples of baked goods or jam may be a good idea to help boost sales. As rhubarb is very tart and rarely eaten raw, you cannot offer raw samples. It needs cooking to bring out the aromatic mellow flavor.

These crops will be in the ground for up to 20 years, so it is important to think long-term before you incorporate them into your field plans. This article covers what you need to know to establish the crops, including a look ahead to what you might expect in the future.

Part 1: Rhubarb

Crop requirements
Rhubarb appreciates deep soil with high organic matter, and as with all long-term crops, it pays to remove perennial weeds before planting. Moderate to high levels of phosphorus and potassium are desirable, and a pH of 6.2-6.8. Once planted, rhubarb remains productive for 8-15 years. This is a very easy crop, with few pests or diseases, requiring little attention.

Rhubarb is a cool climate crop – the north of England is “Rhubarb Central” – the area where rhubarb grows best. I have visited the UK National Rhubarb Collection at Harlow Carr Gardens in Yorkshire. It’s a collection of different rhubarb varieties, a kind of growing gene bank. Rhubarb does require a winter chill period to break the heat-induced dormancy and start spring growth. Varieties vary in their chill requirements, from about 500 hours at between 28°F and 49°F. We successfully grow rhubarb in central Virginia, USDA cold hardiness zone 7 and also National Horticultural Society zone 7 for summer temperatures. I was told by a plant nursery in Tennessee that rhubarb would not grow in such a warm place, but our experience says otherwise. Ideal summer temperatures for this crop average around 75°F. Our summer temperatures include many  days above 90°F. To protect the rhubarb from the heat, we have planted it in a single north-south row, directly west of our asparagus and east of our grapevines. In summer it is shaded on both sides. Choose a microclimate to protect from extreme temperatures and from drying out. It is hardy down to –20°F. Early season open sun exposure is valuable.

Ensure a good regular supply of water from spring, when growth starts, until fall frosts. On the other hand, avoid water-logged sites, as Crown Rot is one of the few diseases rhubarb can suffer from. Very sandy soils aren’t good for rhubarb, unless you can make heavy additions of organic matter. To test drainage at a potential site, dig a 12” hole and fill with water. If the site is suitable, the water will have percolated within three hours.

Choosing varieties and buying plants
Although rhubarb can be grown from seed, it is usually grown from “crowns” (young plants), or  from pieces of crowns divided from established plants. Plants started from seed will be 2 years old before harvest can start. Our plants at Twin Oaks are of unknown parentage, having been divided and moved around the farm a few times. Many people don’t even realize that rhubarb has distinct varieties, and many nurseries only offer one or two. Growers may wish to select varieties based on color (green can be more flavorful), yield, disease resistance or winter chilling requirement. Try to get recommendations from other local growers, or buy several and see which does best. Here’s some information I’ve found, although there may be duplication of names for the same variety:
Macdonald: pinky-red, thin tender, upright stalks, some resistance to crown rot.
Victoria: green tall stalks, good vigor, tart flavor, makes many seed stalks.
Tilden: Good red color, thick stalks.
Valentine: Good red color, medium vigor, few seed stalks.
Crimson: Thick red stalks.
Canada Red: for cooler regions. Red stalks, high in sugars.
Red Cherry: for low winter chill areas. Grown in California.

In the course of writing this article I found a wonderful website, The Rhubarb Compendium  http://www.rhubarbinfo.com/. It includes planting information, propagation, history, recipes, photos, everything you need to know. The Virginia Tech Extension Service has a good new publication on rhubarb by Tony Bratsch:  http://pubs.ext.vt.edu/438/438-110/438-110.pdf, which covers large commercial production as well as information for small growers. Some other university extension sites also have good information on rhubarb, particularly Oregon State, Kansas State, Purdue and the University of Kentucky.

Propagation
Once you have some established rhubarb it is very easy to propagate and have more. The roots of rhubarb become enormous, and even small broken pieces will grow. To divide the crowns, use a sharp shovel or spade to chop through an unearthed crown, creating pieces with 2 or 3 buds on each. This can be done very early in the spring, before growth has started, or late in the fall. If fall is the recommended time for planting other fruits in your area, it will also work as a time for dividing rhubarb. After dividing, let the cut surfaces air dry for a day or two before replanting.

It is generally recommended to renovate rhubarb plantings every 5-10 years by digging up and dividing the roots. This gives the opportunity to move or to increase the planting. If your stalks have become thin, brittle and hollow, it’s time to divide and renovate your planting.

Planting
Plant in very early spring (or late fall as mentioned above). If you buy crowns and cannot plant them when they arrive, store them in a refrigerator, and check to prevent mold growing during storage. After preparing your site and removing perennial weeds, incorporate about 15 tons of compost per acre. On a smaller scale, this translates to one or two shovelfuls of compost per plant. Crowns should be planted 2-3 ft apart, with the bud about an inch below the soil surface. Make trenches or holes 6 inches deep. Fill in the holes or trenches, pack firmly (except directly over the bud), and water well. For multiple rows, space the rows 3 to 4 feet apart. Rhubarb is a large plant and will easily use this amount of space. To combat over-wet soils, use raised beds. Organic mulch will help prevent weeds and keep the soil cool and moist.
   
Growth
Rhubarb grows actively in the spring, and then in most climates, just rests for the summer. Once fall frosts arrive, the leaves and stems will die back to the ground and you can do the annual maintenance.
Give an annual application of compost in the fall when the plant goes dormant, and mulch around the plants with straw or spoiled hay. In early spring come back to your plants, weed, and add more mulch and perhaps more compost if needed as soon as you see the big pink buds emerging from the soil. Provide 1 to 2 inches of water per week.

The warmer your climate, the more flower stalks you will see. Unlike the squarish leaf stalks, flower stalks are round. They quickly grow tall, above the leaves, and have big buds at the top. For maximum rhubarb yield, remove these flower stems as soon as you see them, by cutting them low down, or at least by cutting off the flower buds as you go by. We harvest stalks twice a week in April and May, and cut the flower stems out at the same time.

Harvest
Rhubarb emerges from hibernation once temperatures have reached the upper 40°F range for several weeks. Do not harvest stalks the first year after planting, as it is important to help the plant get well established.

Most people harvest by grasping a thick stem near the base, and twisting and pulling. We like to pull 1/3 of the stalks available and leave at least 2/3 of them growing, but with big plants you can remove half the stalks, provided you leave at least 10 stalks per plant. I believe it is possible  to cut all the stems at ground level, if you have a big commercial planting and need a fast harvesting technique. This may only apply to those growing rhubarb as an annual, setting new plants each year.

The leaves (and any frosted stalks) of rhubarb are poisonous, due to the presence of oxalic acid, so play it safe and cut the leaves off in the field, bringing only the stalks to the shed. We like to stand the stalks upright in buckets and add an inch of water to keep them crisp.

As well as the 6-8 weeks of spring harvest, it is also possible to take one or two harvests in September, in most regions. Some people “force” rhubarb for an earlier spring yield, using rowcovers or field houses, or digging up the roots in late fall and replanting them in a heated greenhouse. Forced plants can be harvested twice a week for 4-6 weeks, but then they are fairly exhausted. A respectable yield is 2-3 pounds of stalks per mature plant per year, or 15 tons per acre.

Part 2: Asparagus

Crop requirements
Asparagus does well in most good soils, provided the organic matter is high. Compost works particularly well, and organic mulches will be helpful. Plan to plant your asparagus in a location that makes weed control easy.  Planting beside a fenceline can be problematic, as grass seeds can blow in. Weed control is crucial to successful asparagus production, so scout for bad perennial weeds before you commit yourself to a particular area. (We failed to notice the Honeyvine Milkweed that now runs through our patch, its roots terminally twined with the asparagus roots.)

Asparagus plantings can remain productive for 15 to 25 years. The year before planting, deal with perennial weeds and, during the year, keep weeds controlled by covering the soil with a series of weed-smothering cover crops such as buckwheat, by making several cultivations, or by using black plastic. If you don’t want to spend a whole year preparing your site, carefully choose an area already in production and sow a cover crop which will winter-kill (oats works well for most of us.) If you have any wild asparagus nearby, dig it up, as it could harbor asparagus pests.

Plan to use the shade created by the asparagus ferns in the summer for cool temperature crops like lettuce (or rhubarb!).

Get a soil test in the fall before planting, and amend with lime as needed for a pH of 6.0-7.5.  Add potassium or phosphorus if necessary.

Choosing plants
The old standard varieties such as Mary and Martha Washington are still available, but are being replaced by hybrids that yield far more heavily, often more than twice as much. We bought Jersey Giant, one of these new hybrids, which is well-adapted to the mid-Atlantic, is resistant to asparagus rust, and consists mostly of male plants which yield more heavily than female ones.

Asparagus is best planted in the early spring in order to give it as much time as possible to grow and store food in the roots. Planting in very cold soil could encourage disease, so wait for some warmth. Some people say the best soil temperature for planting is 50°F. Most growers purchase 2-year-old crowns, although as with rhubarb, it is possible to grow your own asparagus from seed, if you can find seed of your preferred variety.

Planting
If possible, make your rows north-south for quicker drying of dew and rain.  The space between rows could be as little as 18”, or as much as 5’ or even more, if tractor access is required.  (Avoid running tractors directly over the asparagus rows, as you may damage the crowns.) We use a 5’ spacing, which allows us to roll out big round hay bales for mulch.  Plant modern hybrids 18” apart in the row – they need more space than the 12-15” recommended for older varieties.

Older information sources recommend that you plant asparagus in a deep, 15” trench, but research now shows that this is counter-productive.  In fact, yields are heavier from asparagus planted at a depth of four to six inches.  Plant at 4” in clay soil, 6” in sandy soil.  Research has shown that crowns planted deeper simply migrate up through the soil, to settle at 4” after 10 years. When we planted our asparagus 12 years ago, we used a back-hoe to make trenches, following advice to create trenches 12, 15 and 18” deep. The theory was that the more shallow rows would be harvestable first, and the deeper ones would extend the harvest. This turned out to be a figment of someone’s imagination – all the asparagus started to come in at the same time. This led us to do some research, and vow that next time we plant asparagus, we’ll just till out some wide furrows 4” deep.

Make furrows or trenches deep enough to allow 2-4” of compost below the crowns.  As you plant, keep the crowns damp, in covered buckets.  Set aside the smallest crowns, and plant them next to each other – they may do better than if planted between two bigger crowns. (Or perhaps this is another myth created by old asparagus growers – who knows?) Place the crowns 18” apart, with roots spread out, on a ridge or mound of compost in the trench, and cover with 2” of soil only.  Some sources say crowns grow equally well if just tossed in the trench, any way up.  Do not compress the soil covering the crowns.

Buckwheat can be sown between the rows after the last frost, and will smother weeds.  It can be tilled in about 6 weeks later, helping to fill the trenches. Be careful not to till too close to the rows, or you may damage the roots. A week or so after planting, tiny spears begin to grow. Let them grow and fern out. When they are 8 to 10 inches tall, fill in any remaining soil over the crowns. We use a no-till approach to asparagus growing, and mulch between rows with a thick layer of spoiled hay. Some people use black plastic. The alternative to mulching is to cultivate, but avoid cultivation within a foot of the plants, as shallow feeder roots extend some distance out from the plants.

Consider planting an Insectary Strip in your asparagus patch, to attract ladybugs (see the ATTRA publication “Farmscaping”).  Planting sunflowers in the patch may encourage beneficials that might eat pests.

Growth
Research has now shown that asparagus yields better in future years if it is lightly harvested in the first year after planting, in contradiction to old-time advice, which cautioned us to wait till the second year. It’s now recommended to harvest for two or three weeks in the first year. After harvest season the spears will grow taller and fern out, and by fall they will be four or five feet tall, (and even taller in successive years). The photosynthesis in these green ferns will feed the crowns, and replenish them for the next year’s harvest. Asparagus is relatively drought-resistant, but an inch of water per week is ideal. It is important to keep asparagus weed-free, by pulling weeds while they are small, or by hoeing.  Minimize damage to the roots from cultivation, particularly from tilling, as this reduces yield especially once the root system has become extensive. If possible, at the end of each harvest season, give some compost or other organic fertilizer. Be sure to fertilize in the fall or winter, in preparation for the new growth.

After several fall frosts, the asparagus ferns die and turn brown. Then it is time to cut the ferns at ground level and remove them. Take them far from your asparagus bed and compost or burn them to destroy asparagus beetles and diseases that overwinter. Some growers do a controlled burn of their asparagus patch, rather than cut and haul the ferns. Some erect temporary fencing and run poultry in the patch for a short time to eat bugs. If you do this, monitor for soil scratching, and move the chickens elsewhere before they unearth your crowns. The time period could be as short as five days. Ducks and geese are less likely to dig. Those with USDA organic certification will need to read the small print about animal manures and vegetable crops before doing this.

Harvest
Harvest early in the morning, if possible, as the spears are more easily snapped before they warm up. Some people use special knives to cut the spears below the ground, but this risks damage to emerging spears, so we prefer to snap them off at ground level. Others cut at ground level, to provide a tidier appearance. Snapped asparagus is just about all tender and usable – the tough lower ends are left in the soil. It ought to command a higher price!

At the beginning of the season, when the weather is cooler, spears can grow to 9 or 10 inches without ferning out, but in warmer weather, they will open out at a shorter height.  Therefore it may be necessary to harvest shorter spears in warmer weather. To keep life simple, we tell our crew to pick any spears 7” or taller. You may prefer to change the required length according to the temperature. Harvest anything of the right length, if it’s thicker than a pencil.  Pick and discard any very slender, tough spears, and any that are ferning-out. (Slender stems are not more tender than large ones, quite the contrary.)

We use daily harvesting of the entire patch as a way of dealing with asparagus beetles – no ferns are left long enough to leaf out, and beetle eggs are removed from the bed (on the spears) and get no chance to hatch. The eggs can be rubbed off before cooking. The beetles can be hand-picked and crushed while harvesting, especially if temperatures (and the beetles) have not yet warmed up. They are better at eluding capture by dropping and hiding, or flying off, once the day has warmed up. Creep up on them – they drop to the ground if they sense a threat. This article is not the place to go into full details about asparagus beetles, but you certainly need to be aware of the necessity of dealing with them if they show up in your young plants, or you could lose them. Scout for asparagus beetles once a week from the beginning of the harvest period (that’s early April for us).  Inspect 15-20 crowns at four different parts of the field. During the harvest period, the action level is 5-10 adults/100 crowns or 2% of spears infested with eggs.  Post-harvest period, the action level is 5-10 adults/10 crowns. Insecticidal soap can be effective, or as a last resort, rotenone or a rotenone-pyrethrum mixture can be used, but these are also toxic to other creatures.
Stop harvesting in the first season after four weeks at the most, sooner if the asparagus begins to produce more and more small spears.  A fully established asparagus patch (from the fourth year on) can be harvested for 8 weeks, sometimes a bit longer. Finish the harvest season when the thickness of the majority of the spears is less than the size of a pencil.  

If you are expecting a frosty night, harvest all edible spears, regardless of size, as they will otherwise get frozen and be wasted.

We harvest into short buckets so that the spears will be standing on end when the bucket is upright. Then we take the harvested spears into a cooler at temperatures of 34-40°F as soon as possible. We add an inch of water to the buckets, to keep the spears fresh. 100 feet of asparagus will yield at least, and probably more than, 50 pounds.  The usual suggestion is to plant 10 crowns per person, or up to 20 if you plan to can or freeze.

Maintenance
Care of asparagus involves pre-season weeding and mulching, in-season harvesting, weeding and pest control, post-season weeding, fertilization and mulching, and down-season cutting and hauling of ferns, fertilizing and perhaps weeding again. Hopefully this is enough detail to let you decide if planting an asparagus patch is right for your farm.
   
Suppliers
Mellingers Inc, 2310 W. South Range Rd, North Lima, OH  44452-9731; 216-549-9861; www.mellingers.com/
Nourse Farms, 41 River Road, South Deerfield, MA 01373. 2 varieties of rhubarb, 4 of asparagus. (413) 665-2658; www.noursefarms.com/
Indiana Berry and Plant Company, Huntingburg, IN. 4 varieties each, rhubarb and asparagus. (800) 295-2226;  www.inberry.com/
Daisy Farms, Dowagiac, MI. 1 rhubarb variety, 6 asparagus varieties. (269) 782-7131; www.daisyfarms.net/
Johnny’s Selected Seeds, Winslow, ME. 1 rhubarb, 3 asparagus varieties. (877) 564-6697; www.johnnyseeds.com/
Jersey Asparagus Farms, Pittsgrove, NJ. www.jerseyasparagus.com

Other resources
ATTRA “Organic Asparagus Production”:  www.attra.org/attra-pub/asparagus.html
“Farmscaping to Enhance Biological Control”  www.attra.org/attra-pub/asparagus.html
Nourse has online planting guides for both asparagus and rhubarb:   www.noursefarms.com/HomeGardeners/PlantingGuide/
Jersey Asparagus Farms also has planting guides: www.jerseyasparagus.com/hgplantingguides.htm
VABF Infosheet on Organic Asparagus: www.vabf.org/infosheets/8-06.pdf

Pam Dawling is the garden manager for Twin Oaks Community in Louisa, Virginia. She can be reached at pam@twinoaks.org.