PTP_2007_12_Bare_Root

PLANTS THAT PRODUCE

Bare Root Edibles

By Richard Frost

This month we introduce another new column about food (the Garden Gourmet, at left, debuted in November) – but this one is about food you can grow at home. Member Richard Frost makes a great point below when he suggests planting edibles as a way to cut down on your water needs. Some of the plants we’ll be learning about from him use lots less water than the average lawn. And, unless you’re a rabbit, who wants to eat lawn clippings when you can sink your teeth into perfectly ripe home-grown peaches, bababerries, or other yummy fruits and veggies?

Bare-root season is upon us. Your local nurseries are ready and waiting with availability lists and order forms for deciduous fruits and vegetables. For fruit trees, I recommend a nursery that obtains plants from Dave Wilson Nursery – California’s premier commercial grower. Not only will you get a quality plant on the correct rootstock, but also a plant that is likely to work in our area. Their website http://www.davewilson.com has loads of helpful information for home fruit gardeners plus descriptions and photos of their line of trees.

Your local nursery can help you narrow down the vast selection to a few choices that fit specific areas of San Diego county. Free information tailored to coastal regions of San Diego can also be found at www.plantsthatproduce.com. Some of my favorites include Improved Green Globe Artichokes, Youngberry, Bababerry, Black Satin Blackberry, Eversweet Pomegranate, Green Gage Plum, Saturn Peach (not Donut), Panamint Nectarine, Janice-Kadota Fig, and Pettingill Apple.

With water shortages looming, you might ask, “Why are you suggesting the cultivation of fruits and vegetables?” Answer: because many of these garden edibles require far less water than lawns and other hydrophilic ornamentals that many of us are now growing. Take a moment to consider a single lawn sprinkler. The water output rate is 2 to 5 gallons per minute – including so-called low volume heads operating at standard pressure. Now multiply gallons per minute times number of sprinkler heads times number of watering minutes per week… ouch!

A home fruit tree pruned to 8¢ high and 12¢ or so wide requires 30 to 50 gallons of water per week to produce quality fruit, depending upon variety and season. Fruiting vines and large shrubby vegetables require 10 to 20 gallons per week. Smaller vegetable plants, such as cauliflower, 8-ball zucchini or stringless green beans, will only need 5 to 10 gallons per week. There are some exceptions – like Avocado which requires “double water.”

The five keys to being water wise in the garden are: (1) know the water requirements in terms of “how much” and “how often”, (2) have a water delivery system that meets those requirements, (3) if the soil drains too little you'll need to treat it with liquid gypsum, or if the soil drains too much it will need a careful amount of kaolinite added prior to planting, (4) treat the soil with weak carbonic acids – so called humic acids that insure the soil chemistry works properly (see note 1), and (5) mulch heavily with coarser-grained materials (not fine-grained compost) immediately after planting to promote water retention in the soil. Avoid mulching up against the trunk: mold and little critters will eat away at the bark. An alternative to mulch is to plant a nitrogen-fixing cover crop of mixed clover or similar.

When planting fruit trees, vines, bushes, or vegetables it is advisable to first loosen compacted soils. Ideally for a bare-root tree or 5- to 15-gallon potted tree, you will want to excavate a hole 4¢ diameter by 3¢ deep (see note 2). A mini-excavator is perfect for this job. A smaller hole simply means that the tree will develop much slower. For vines and bushes, a 2¢ diameter by 2¢ deep hole will suffice. For a vegetable patch, cultivate 3¢ wide and down 6-8². A 13 horsepower rototiller will get the job done very quickly, and a 5 horsepower rear-tine model does a satisfactory job as well.

Regardless of what you are planting, remove all rocks larger than a golf ball from your excavated or tilled soil. In San Diego County, this often results in a significant loss of soil volume. You can mix back in up to ½ and ½ with a bulk planting mix or a mixture of well-cured fine-grained compost with ¼ inch pumice. This latter choice should be done one or more months in advance because fresh plant material deep in the ground is bad for developing roots.

Plant your items according to nursery recommendations: a bit high in the ground so that after settling the crown of the plant is not below the average soil level. Also keep any graft joint or grafting scar well above ground. And most importantly, go out there and do your part for water conservation: grow some plants that produce!

Notes:

1. Wherever clays are significantly present, humic acids are needed for non-natives. In San Diego County, 80% of the surface geology has significant clay content. Adding humic acids elsewhere is never harmful. Several mainstream brands of fertilizers and soil conditioners contain humic acids; e.g., Gro-Power, Dr. Earth, some Kellogg Garden Products, and more.

2. Regarding deep holes: the main purpose of a hole is to loosen compacted soils. Our soils are not only compact clays, but in housing developments they have been mechanically compacted. In their native environs, the plants (or rootstocks) we are referring to would develop a root system that mirrors the tree in both width and height. Commercial growers would find my recommendations modest if not conservative. In my encounters with others -- particularly as an employee at a major nursery, everyone who has a stunted fruit tree planted it in a small hole. Eventually it will grow up, but it takes a lot longer for the roots to develop. Persons who have followed my suggestions come back amazed that trees could grow that vigorously.

Richard Frost is a member of SDHS and the California Rare Fruit Growers. Special thanks to Richard Wright and David Ross for decades of inspiration. For more information, see www.plantsthatproduce.com.