Perennial vegetables

Sweet corn does not fit in with any of the other family groups. It makes a useful filler for gaps in your rotation plan. Also exempt are the perennial vegetables, which occupy the same space year after year (see overleap. 

Perennial vegetables, which can stay in the same spot for many years, obviously do not fit into the usual crop rotation. 

When replacing perennial vegetable plants, or dividing and replanting (see p.l93), do not replant on the same site. Check for pests and diseases on perennial crops, especially those such as nine-star broccoli that are related to other vegetables. Pests and diseases that become established on perennial crops can be a source of infection for other plants. 

Cress, mustard, and radishes are used as sprouted seeds, and many can be eaten as seedling crops. The perennial vegetable seakale is grown for its forced shoots, harvested in mid- to late winter. Kohlrabi produces crisp and juicy swollen stems. 

Perennial vegetables such as globe artichokes and rhubarb crop much more quickly if grown from divisions or "offsets" taken from a mature plant (see also Herbaceous Plants, p.J93) rather than seed. Asparagus should not be harvested until plants are in their third year, so one-year-old plants, known as crowns, are usually planted (see above, far right). Jerusalem artichokes are grown from tubers, like potatoes, and seakale from sections of fleshy root known as "thongs."... 

A higher number of crops, including perennials, vegetables, and herbs ... 

Sweet potatoes are perennial vegetables grown as annuals in temperate regions for their tuberous roots. While they are tropical natives, you can grow them if you get at least 100 frost-free days. Cultivars have light yellow to purplish red skin, and white to deep orange flesh. 

Steiger JW and Webb RH, Recovery of Perennial Vegetation in Military Target Sites in the Eastern Mojave Desert, Arizona, Open-File Report OF 00-355, U. S. Geological Survey, Washington, DC, 2000. 

Urena and Abutilon. These are less important vegetable fibers of a jute-like nature. Urena lobata (Cadillo) of the mallow family (Malvaceae) is a perennial that grows in Zaire and Brazil to a height of 4—5 m with stems 10—18 mm in diameter. Because of a lignified base, the stems are cut 20 cm above the ground. The plants are defoflated in the field and retted similarly to jute and kenaf. The retted material is stripped and washed and, in some cases. 

There is extensive evidence that allelopathy may contribute to patterning of vegetation in natural ecosystems (11). Distinct zones of inhibition are present under and adjacent to a variety of woody species, and often toxins from their litter are implicated (J2). One might speculate that aggressive perennial weed species quickly gain dominance by exploiting allelopathic mechanisms. 

As tree fruit species are perennial crops, year-to-year influences are often detected. For example, factors in the previous year(s) (e.g. water or nutrient deficiency, hail storm damage, shoot deformation caused by aphids, too high or too low crop load) strongly influence the tree s performance in the next year (Tromp and Wertheim, 2005). Thus, a major objective of agronomic practices used is to buffer the orchard from stress and to keep trees in a balance/equilibrium between vegetative and generative activity. 

Perennial survival Perennial weeds make use of a range of mechanisms for their longterm survival and spread. This can include both seed and vegetative means such as runners, stolons, rhizomes and long, deep taproots. 

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