The Missouri Gravel Bed (MGB) is a new method for handling bareroot nursery stock. In the spring, dormant plants are placed with their roots in an irrigated bed of creek gravel and held for up to six months or longer before being planted bareroot (in full leaf) in the field or landscape. It is not a growing method, but can be used by growers and retail and landscape nurseries to extend the planting season and to greatly simplify the handling of bareroot stock. Research at the University of Missouri and Sherman Nursery have shown that plants can be removed from the gravel and planted at any time during the summer with a survival rate equal to those of container grown or B&B material. 

The Missouri Gravel Bed will allow you to capitalize on the advantages of bareroot nursery stock. Since bareroot stock is grown with no up-front cost of containerization, and costs much less to harvest than B&B, it can be sold without passing on these extra costs. Also, since no hardware or soil ball are shipped with the plant, shipping costs are greatly reduced. Another advantage of bareroot is that there is no interface between a soil ball into which the plant is placed. There is immediate, direct contact between the back fill soil and most plant roots. Some nurseries have hesitated to use bareroot material because it is often considered to have a short planting season. Bareroot is also considered by some to be perishable and difficult to handle. The MGB helps to solve those concerns. Plants heeled into an automatically irrigated gravel bed while dormant essentially take care of themselves and can be removed from the gravel at nearly any time for potting or planting.

The best kind of gravel to use is a material with a maximum particle size of about 3/8 inch. For plants such as pines that require excellent drainage, it is best to use a gravel with most of the fine particles screened out. For general use, a gravel with particles ranging from 3/8 inch down to coarse sand works very well. Check with your local sand-gravel dealer to see what is readily available in your area. If the 3/8 inch gravel in your area has all the fines washed out, then a mix of 3/8 inch gravel (60%) and coarse sand (40%) works well. Do not use limestone. 

The easiest way to make a gravel bed is simply to dump a load of gravel and spread it approximately 18 inches deep. For a more attractive bed, sides can be constructed with landscape timber, railroad ties or treated lumber. An irrigation system using spray stakes, drip emitters or a soaker hose work well. Keep the spray pattern as close to the gravel surface as possible to avoid wetting the foliage. Since water does not move laterally in gravel, it is best to wet the entire surface of the gravel occupied by roots. Activate the irrigation system with a solenoid valve and time clocks just like you would in a mist system. A 24 hour clock should turn the system off at night and a 60 minute timer works well when it is on during the day. During rapid shoot growth in May and early June, it may be necessary to irrigate at mid-day as often as 1 minute every 10 minutes to prevent excessive wilting of some species. At other times irrigating for a few minutes two or three times a day will be sufficient. Check the gravel around plant roots occasionally to make sure it is not dry.

It might be desirable, if possible, to recirculate your irrigation water. This conserves water, reduces potential problems with puddling near the bed and prevents unwanted runoff. Placing the bed on a slight slope with 6 mil poly under the gravel will allow irrigation water to be collected in a sump for recirculation. 

Nutritional needs of plants in the Missouri Gravel Bed can be easily satisfied with the use of a slow release (3-4 month) granular fertilizer. Gravel and gravel-sand mixes provide little nutritional value; therefore, adding fertilizer is necessary to promote growth and development and good color of the plants. As little as 2-3 tablespoons of a 3-4 month (21-4-10) fertilizer top dressed on top of the gravel is sufficient for the growing season. 

Plants pulled from a gravel bed are not nearly as perishable as most people think. Retail customers may be hesitant to buy plants with their roots right out in the open; however, once they see the results, is should not be hard to convince them that Missouri Gravel Bed trees are not as perishable as they presumed. The easiest way to handle them is to lay them on a sheet of polyethylene, sprinkle them with water and wrap them in a bundle tied with twine. A bundle of 15, 6-foot trees fits easily in a small station wagon (as compared to 2 container grown trees the same size). After mid-June, when the leaves have hardened up, simply placing the roots in a plastic bag will usually suffice if the plants will be planted within a few hours. A bundle of MGB plants will stay in good condition for several days or longer if kept in a cool garage. While gravel cultured plants are not particularly perishable, it is important that roots never be allowed to dry out. If the roots are kept covered with plastic until planting and a bucket of water is poured into the planting hole after the plant is set (about 2 gallons for a hole 18 inches in diameter), survival can be essentially guaranteed. 

• Lower growing costs (no container or soil)

• Lower harvesting costs (no special harvest equipment)

• Lower shipping costs (less weight, bulk)

• Easy to set up

• Transplant rates (properly timed) of 100%

• Retail customer hesitation to bareroot stock (perceived as perishable)

• Early moving- there is a period in spring when the plants are putting on top growth and the roots are not yet well developed in the gravel. Plants taken from the gravel during this period may have less than 100% survival rate.

Please call us if you have any questions regarding the Missouri Gravel Bed.