Two queries involving edible plants are the focus of this week’s column.
Q: I recently moved into a new home and have discovered all the wonders of spring. Many items have emerged in the former vegetable garden, including a mound of asparagus. We harvested some beauties, and now there are hairy stocks remaining. Do I need to do anything with this mound until next spring? The earth is very hard, compact and dry in the region. Should I amend the soil or what?
– Lisa Klein, Thousand Oaks
A: Thousand Oaks is famous for its intractable clay soil. You should amend it by any means available to you. One of the most important rules of backyard horticulture is that bare soil should not be allowed anywhere at any time. Your soil should never be exposed to the elements, but kept covered year-round with mulch (any material that minimizes evaporation of moisture from the soil surface) until the moment arrives that you wish to plant in it. Mulch does more than protect soil from baking and hardening caused by the pounding rays of the sun. Mulch, as it breaks down, also makes the soil soft, rich in minerals and micro-organisms, and easy to stick a shovel into when you finally decide to plant.
For long-term soil improvement, spread amendments several inches thick over the bare spots in your garden. As the amendments break down, pile on more. Some amendments are free of charge, such as compost created from a mixture of grass clippings, shrub prunings and wood chips. (Obtain wood chips by flagging down a tree trimmer and telling him he can save a dump fee by depositing his load on your driveway.) Straw, cheaply available by the bale at feed and animal supply stores, also makes an excellent layer of mulch. A procedure to more quickly soften hard soil involves soaking the ground for several days with a slowly trickling hose. Then, spread a 2- to 3-inch layer of Gro-Mulch or any other highly decomposed compost over the soil surface. Work this material into the soil to a depth of 6 inches. If you have a large area, you would want to do this with a roto-tiller. For small areas, a spading fork is probably the best tool for incorporating amendment while, at the same time, turning over and aerating the soil. If you have a strong back, you could also use a mattock or a spade to break up hard clods of earth.
That being said, it would not be advisable to dig up the soil in the immediate vicinity of your asparagus. Asparagus spears grow from subterranean rhizomes that spread out several feet from the asparagus mound. Since asparagus prefers an acidic soil, it would make sense to mulch the surrounding area with an acidic material such as peat moss, oak leaf mold or a finished compost such as Nitrohumus, all of which should be available by the bag at your neighborhood nursery.
By the way, should more asparagus spears arise between now and the fall, you should only harvest them if their diameter is larger than pencil size. Harvest of thin spears will reduce the vigor of your mound, resulting in fewer spears next spring.
Q: I planted some sunflower seeds, and they have just sprouted. Is there anything special I need to know to ensure that these seedlings grow into the 8- to 12-foot sunflowers they are supposed to become?
– Henry Davis, North Hills
A: Like seedlings of most vegetables and annual flowers, sunflower seedlings must be thinned out in order to grow to their maximum size, only more so. You must space your plants no less than a foot apart from each other within the row; multiple rows should be separated by at least two feet. Sunflowers require ample irrigation. If not given enough water, their heads will flop. Mulching the soil under sunflowers is highly recommended.