Prepare Ahead for Summer Weed control
By Bob Randall, Ph.D.
Spring 1999
Every fall Urban Harvest is asked what to do about raised beds that have filled with Bermuda and nut grass while gardeners, particularly at schools, took a summer vacation from the garden. There are remedies available to reclaim a weedy bed, but far better is to prevent perennial weeds like Bermuda, nut and Johnson grasses from getting there in the first place. If you had this problem last year, the time to take corrective steps is in the next few months. There are basically two helpful strategies depending on whether someone will be regularly weeding your garden this summer or not.
No Regular Gardners
If weeding will be a major problem this summer, then what you need is a lot of mulch and newspaper, and quite a few sweet potato sets to plant. Essentially, the idea is to replace spring vegetables with sweet potatoes. Order rooted sweet potato sprouts (sets) equal to the size of your garden. The formula for calculating this is:
1. Figure out the number of feet of bed longwise you want to plant
2. Multiply by two and one half
3. To purchase, if you are a community or school garden send an order (see box) with payment to Urban Harvest by March 15 for early May delivery. The cost is 15 plants for $1. When delivery occurs, you will be called to pick them up within a few days at Urban Harvest offices M-F 10-6 pm.
Alternatively, individuals, groups of friends and community gardens can order directly from Fred’s Plant Farm, have them delivered to your door on the date you want, but pay a higher price ($15-20 + delivery charges for 50-100 plants). When they arrive, either plant them in already prepared beds, or simply plant each group of ten close together in a temporary bed until you are ready to plant.
Sometime between May and July, get some help, clear your beds and create a high hill down the middle of each raised bed. You do this by taking a shovel and digging out the soil inside the frame on either side of the bed. Dig out an area about one foot wide and the length of the bed, dumping the removed soil down the center, so as to create a new bed 2-3 ft. wide and perhaps 16 inches high. Then flatten the top of the bed and plant two rows of sweet potato plants (sets) about 10 inches apart.
Next, lay about 10 sheets of wet newspaper on the sloping sides of the bed, and layer 3-6 inches of hay or native mulch on the newspaper. Water the sets well over the next few weeks. Pull any weeds that grow. If the summer is very dry and you see brown or yellow leaves, water well once or twice, but otherwise don’t bother.
Dig up the potatoes in a “Treasure Hunt for Buried Gold” after three months or by December 1 at the latest. The longer you wait, the bigger the sweet potato harvest, the less hot weather weeding you will have, but you will have fewer fall crops also.
If Your Regularly Weed
Summer gardeners who will weed can enjoy okra, chiles, cantaloupes, long beans, butterpeas, cream peas, cucumbers, sweet corn, basil, and more. To avoid having a grass patch at summer’s end, one needs to first learn to identify three bad grasses: nut grass, Bermuda grass, and Johnson grass; second, prevent them from spreading by regular weeding.
Weekly vigilance and good wide walls on your raised beds can stop these grasses. In summer, the hours from 6-8 am and 5-8 pm will be easiest on gardeners.
Weeding these grasses can only be done by removing each and every one by the roots whenever one is spotted either inside the bed or creeping through the blocks or boards into the bed. Nut grass grows underground by sending out runners in all directions from the underground bulb to create several more bulbs. Bermuda spreads by sending out runners in all directions on top of the soil, but puts down roots at each leaf node. Under normal circumstances, neither grass spreads by air, so if you keep these grasses from creeping into the bed, you won’t have any in the bed EVER.
As with sweet potatoes, whenever possible mulch with hay, or native mulch on newspaper.
