The Wurtz avocado tree, often called ‘Little Cado,’ is popular among home gardeners due to its compact size. This variety typically reaches a mature height of only 8 to 10 feet, making it the only true dwarf avocado and ideal for small gardens or large containers. It is a hybrid of Mexican and Guatemalan avocado types, producing flavorful, green-skinned fruit ready for harvest from late spring through early fall. While more tolerant of cooler temperatures than many varieties, it should be protected from harsh frost, as it is generally hardy down to about 25°F to 30°F.
Site Selection and Planting Techniques
The proper location and planting method are important for the long-term health of a Wurtz avocado tree. The tree thrives best in full sun, requiring at least six to eight hours of direct sunlight daily. Protection from strong winds is also beneficial, as the tree’s wood can be brittle, and strong air movement can stress young trees.
Avocados have a shallow, fibrous root system, with most feeder roots existing in the top six inches of soil, making excellent drainage a requirement. The soil should be fertile, rich in organic matter, and maintain a slightly acidic to neutral pH range, ideally between 6.0 and 6.5. If the native soil is heavy clay, plant the tree in a raised mound up to two feet high and five feet wide to ensure water drains freely away from the root zone.
When planting, dig the hole as deep as the root ball and two to three times as wide to allow for root expansion. Place the root ball so the top of the potting mix sits slightly above the surrounding soil grade to prevent the trunk from being buried. This avoids the suffocating effect of planting too deeply on the tree’s oxygen-dependent root crown. After backfilling the hole with native soil, water thoroughly to settle the soil and eliminate air pockets.
Routine Water and Nutrient Management
Consistent watering is a delicate balance for the Wurtz avocado; the tree requires plenty of moisture but is highly susceptible to root rot in waterlogged conditions. Young trees typically need water two to three times per week, while established trees should be watered deeply enough to moisten the entire root zone. Seasonal adjustments are necessary, requiring more frequent watering during warm, dry periods and less during cooler weather to prevent soil saturation.
Fertilization is required throughout the active growing season, generally running from early spring through early autumn. Young, non-bearing trees benefit from fertilizer application every three to six weeks to promote vigorous growth. A balanced fertilizer with a ratio similar to 5-2-3 or 8-1-8 is recommended, as avocados are heavy nitrogen users and require micronutrients like zinc.
For mature, fruit-bearing trees, the nutrient focus shifts to support fruit development, increasing the need for potassium. Apply fertilization following the manufacturer’s instructions, ensuring granules are spread evenly beneath the canopy but kept away from the trunk to prevent root burn. Applying a coarse organic mulch, like wood chips, over the root zone helps retain soil moisture and protects the shallow roots from fluctuations.
Pruning for Health and Structure
Pruning the Wurtz avocado is primarily a maintenance activity focused on shaping the tree and promoting air circulation, rather than aggressive size control. Since the Wurtz is a dwarf variety with a naturally compact habit, it does not require the extensive height reduction needed by larger avocado types. The most suitable time for major pruning is in late winter or early spring, just before the tree begins its flowering cycle.
The goal of pruning is to remove dead, diseased, or crossing branches that restrict airflow, which helps reduce the risk of fungal issues. For young trees, pinching the tips of terminal shoots encourages lateral branching, creating a bushier, more structurally sound canopy. Suckers that emerge from below the graft union must be removed immediately, as this growth comes from the rootstock and will not produce Wurtz fruit.
Pest and Disease Prevention
The most serious threat to the Wurtz avocado tree is root rot, caused by the fungus Phytophthora cinnamomi, which thrives in wet, poorly drained soil. The primary prevention measure is ensuring superb drainage during planting and avoiding overwatering, as once the fungus is established, it is difficult to eradicate. Symptoms of root rot include pale, wilted leaves and a general decline in the tree’s vigor.
Common pests include avocado thrips, mites, and avocado lace bugs, which feed on the leaves and fruit, causing cosmetic damage. Thrips and mites can be managed through cultural controls, such as spraying the foliage with a strong jet of water to physically dislodge them. For more persistent infestations, applications of horticultural oil or neem oil can disrupt the pest life cycle.
A grafted Wurtz tree, when properly cared for, can begin setting fruit within one to two years of planting. The fruit is ready for harvest when it reaches full size and the skin begins to turn a duller green, but it will not soften until picked. After harvesting, allow the fruit to ripen at room temperature for seven to ten days before eating.