March is a pivotal month in the Tucson garden, marking the shift from cool winter temperatures to the warm and dry conditions of spring. Plants are beginning to wake up from dormancy, and the window for many gardening tasks—such as pruning, planting, and fertilizing—is at its peak. By staying on top of key maintenance tasks, you can ensure a productive and thriving garden before the intense summer heat arrives.
This guide provides a comprehensive breakdown of what to do in the Tucson garden in March, covering pruning, planting, soil care, watering, pest management, mulching, and special considerations for the upcoming season.
Pruning and Maintenance
Pruning is essential for maintaining healthy growth, promoting flowering and fruiting, and managing plant size. In March, the goal is to complete any remaining winter pruning while allowing plants to push out new spring growth.
Roses
March is the last chance to prune roses before new spring growth gets too far along. If pruning is delayed, plants may experience stress in the warming temperatures. The key to successful rose pruning is removing weak, diseased, or dead canes while keeping the strongest ones intact. The remaining canes should be trimmed to an outward-facing bud at a 45-degree angle to encourage proper airflow and prevent fungal diseases. After pruning, applying a slow-release balanced fertilizer (like 10-10-10) will encourage vigorous new growth and improve blooming.
Citrus Trees
Citrus trees should be lightly pruned in March, but major shaping should be avoided. Removing suckers from below the graft and small dead branches is beneficial, but over-pruning can lead to sunscald. Since citrus trees store energy in their leaves, pruning too much foliage can reduce fruit production and expose bark to sunburn. If frost damage is evident, it’s best to wait until new growth appears before cutting back damaged wood.
Grapevines
March is the last opportunity to finish pruning grapevines before the buds swell and growth resumes. Whether you use the spur or cane pruning method, it’s important to remove excess old wood and leave only strong, productive canes for this season’s fruiting. Unpruned vines can become tangled and less productive, making it harder to manage the plant later in the season.
Deciduous Fruit Trees (Apples, Peaches, Plums, Pears)
For fruit trees, pruning in early March should focus on removing suckers, water sprouts, and crowded growth to improve airflow and light penetration. Well-pruned trees produce better fruit, as thinning prevents excess competition among developing fruit. In peaches and nectarines, thinning fruit later in March helps prevent branches from being overburdened, which can lead to breakage..
Shrubs and Perennials
Frost-damaged shrubs and perennials—such as Lantana, Texas Rangers, and Ruellia—should be pruned back to stimulate new growth. If left untrimmed, dead portions of the plant can lead to disease or pest infestations. Additionally, ornamental grasses such as muhly grass and deer grass should be cut back to a few inches above the ground to encourage fresh, lush growth.
Planting
March is an excellent time for planting in Tucson, as the soil is warming but not yet too hot. Whether starting vegetables, flowers, or trees, early planting gives roots time to establish before the heat of summer.
Vegetables
Warm-season vegetables such as corn, beans, cucumbers, melons, squash, and pumpkins should be direct sown into well-prepared soil. These crops require warm temperatures to germinate, and planting them now ensures they have a full growing season before the intense heat of summer. Tomatoes, peppers, and eggplants should be transplanted rather than direct-seeded to allow for a strong start before temperatures rise. Herbs like basil, oregano, thyme, rosemary, and lemon verbena also thrive when planted in March.
Flowers
For color and pollinator attraction, annuals such as pentas, zinnias, cosmos, sunflowers, and vinca can be planted now. These flowers are heat-tolerant and add beauty to both ornamental and vegetable gardens. Perennials such as penstemon, verbena, rudbeckia, salvias, and lantana establish well in March, preparing them for a long blooming season.
Trees and Shrubs
March is a great time to plant citrus trees, desert trees (palo verde, mesquite, acacia), and flowering shrubs (Texas ranger, fairy duster, leucophyllum). However, frost-sensitive plants like bougainvillea should be planted later in the month to avoid late cold snaps.
Soil
Healthy soil is the foundation of a productive garden. In March, focus on replenishing nutrients lost over winter. This can be done in several ways:
Compost – A 1-3 inch layer of well-aged compost mixed into the top 6 inches of soil enhances microbial life and nutrient availability.
Aged Manure – Well-composted cow, horse, or chicken manure adds nitrogen and improves soil aeration.
Worm Castings – Rich in beneficial microbes and nutrients, worm castings help create a loose, fertile soil structure.
Peat Moss or Coconut Coir – Helps retain moisture, especially useful for sandy or fast-draining soils.
Mulch (Wood Chips or Straw) – Applied as a topdressing, it helps retain moisture, prevent erosion, and gradually decomposes into the soil.
Fertilization
Citrus trees that haven’t been fertilized yet–Valentines Day is the traditional spring citrus fertilizer date–should be fertilized with a high-nitrogen citrus fertilizer applied around the drip line and watered deeply to encourage strong growth. Other fruit trees benefit from a balanced organic fertilizer, especially if they are entering their fruiting stage.
Roses
Roses should be fertilized every 4-6 weeks with a balanced fertilizer or a slow-release organic feed. A layer of compost and mulch also helps maintain soil moisture and supports healthy root growth.
Vegetable Gardens
Adding compost, worm castings, and well-rotted manure enriches the soil before planting. Organic fertilizers such as fish emulsion or kelp meal provide essential nutrients for young plants.
Watering
March brings warmer temperatures, which means plants require more water. However, it’s important to avoid overwatering, which can lead to root rot.
- Citrus & fruit trees: Deep water once per week to ensure deep root penetration.
- Vegetables & flowers: Water deeply 2-3 times per week, depending on temperature.
- Newly planted trees/shrubs: Water every few days to help establish strong roots.
- Established desert plants: Deep water every 2-3 weeks, as they are adapted to drought conditions.
Checking drip irrigation systems for leaks or clogged emitters is essential as watering needs increase.
Pest & Disease Management
As the weather warms, pests become more active. Early detection prevents infestations.
- Aphids: Common on roses and fruit trees; use neem oil or insecticidal soap.
- Cabbage loopers: Damage brassicas like kale; apply Bacillus thuringiensis (Bt).
- Snails and slugs: Found in moist areas; use iron phosphate bait or hand-pick.
- Powdery mildew: Affects cucumbers and squash; improve air circulation and avoid overhead watering.
Mulching & Weed Control
A fresh layer of mulch in March conserves moisture, regulates soil temperature, and suppresses weeds. Applying a 2-4 inch layer around trees, shrubs, and vegetables improves overall garden health.
Weeds should be removed before they flower to prevent reseeding. For long-term control, a pre-emergent herbicide (like corn gluten meal for organic gardens) can reduce future growth.
Special Tasks
- Harvest citrus: Oranges, lemons, and grapefruit are still ripening.
- Thin fruit: Apples, peaches, and plums need fruit thinning to prevent branch breakage.
- Prepare for summer: Install shade cloth for vegetables and sun sensitive plants to prevent sunburn.
March is a busy and rewarding time in the Tucson garden. By focusing on pruning, planting, fertilizing, and pest control, your garden will thrive as temperatures rise. Keeping up with these tasks ensures a productive season leading into the heat of summer.