When to fertilize what — built for Phoenix yards.
Pick what you're growing — citrus, fruit trees, palms, roses, shrubs, vegetables, Bermuda turf, desert natives — and get a real month-by-month schedule with what to apply, how much, why, and how to water around it. Print it, download a branded PDF, or email it to yourself.
A few things this tool will NOT do: recommend a brand, ignore your soil, or feed a stressed plant. Those calls need a soil test or a real walk-through. If you're a Guardian member, the full version drives off your actual plant inventory and sends reminders.
Step 1 — Pick what you're feeding
Multi-select. Chips toggle. The schedule below updates instantly. Calibrated for Phoenix / low-desert AZ (USDA 9b).
Edibles & fruit
Trees
Desert & native
Shrubs & ground cover
Flowers & roses
Turf
Step 2 — Your month-by-month schedule
3 months with applications for the categories you selected.
February
1 applicationCitrus
edibles- Apply
- Balanced citrus food (e.g., 8-8-8 with micronutrients — iron, zinc, manganese)
- Rate
- 1 lb of actual N per inch of trunk diameter, split evenly across the year (≈1/3 now)
- Why
- Pre-bloom feeding fuels flower set and early fruit development.
- Watering
- Water deeply the day before AND the day after to drive nutrients past the salt zone.
May
1 applicationCitrus
edibles- Apply
- Balanced citrus food OR ammonium sulfate (21-0-0) if soil already tests high in P and K
- Rate
- Second 1/3 of the annual N total
- Why
- Memorial Day feeding supports fruit sizing through the heat.
- Watering
- Deep-water before and after; the next irrigation cycle should run extra-long.
September
1 applicationCitrus
edibles- Apply
- Balanced citrus food (final pre-winter feeding)
- Rate
- Final 1/3 of the annual N total
- Why
- Labor Day feeding finishes the year's fruit and sets the tree up for winter dormancy.
- Watering
- Deep-water before and after — this is also the year's most important salt-flush irrigation.
Three rules that apply to everything above
- Water deeply the day before and the day after every feeding. Dry soil plus fertilizer is the fastest way to burn roots. The second deep watering also flushes salts down past the root zone.
- Never fertilize a stressed, wilted, or freshly-transplanted plant. Solve the stress first. Feeding a stressed plant accelerates the decline.
- When a plant looks bad, soil-test before chasing a deficiency. Iron chlorosis and salt burn look almost identical — and they need opposite treatments. A $20 soil test saves a season of guessing.
Want the full version?
The Guardian Fertilizer Planner reads your property's actual plant inventory, adjusts for your soil pH, irrigation type, and microclimate, sends you a reminder the week each feeding is due, and lets our crew tune your schedule and log every change. Part of your paid Outdoor Guardian membership.
Learn about Outdoor GuardianCommon fertilizer questions
When should I fertilize citrus in Phoenix?+
Three times a year: around Valentine's Day, Memorial Day, and Labor Day. Split the annual nitrogen total (roughly 1 lb of actual N per inch of trunk diameter) into thirds. Always water deeply the day before and after each feeding.
Should I fertilize my mesquite or palo verde?+
No. Native desert legumes fix their own nitrogen and grow weak, wind-prone branches when fertilized. The most common cause of snapped mesquite trunks in monsoon is unnecessary nitrogen feeding the prior spring.
Why do palms need a special fertilizer?+
Palms need extra magnesium, manganese, and potassium that aren't in standard tree or turf food. A palm-specific blend (often 8-2-12 with micros) prevents frizzle-top, yellowing fronds, and the slow decline that follows years of being fed lawn fertilizer.
Can I fertilize my Bermuda lawn in winter?+
No — dormant Bermuda doesn't absorb nutrients, and the feed mostly goes to winter weeds. Bermuda feeding window is April through September. If you overseed with rye, that gets a separate cool-season schedule.
Does this schedule work for the high desert or northern AZ?+
The schedule is calibrated for Phoenix and the low desert (USDA 9b). Higher elevations (Prescott, Flagstaff) should shift spring applications 2–4 weeks later and fall applications 2–4 weeks earlier. The relative spacing between feedings stays the same.
Should I use a granular or liquid fertilizer?+
Granular slow-release is generally easier and more forgiving for trees, shrubs, and turf. Liquid (diluted) is better for short-cycle annuals and vegetables because you can adjust strength quickly. For a stressed or freshly-transplanted plant, neither — solve the stress first.