Arizona gardeners should plant nasturtium in the cooler months of fall or early spring. Knowing the Best Time To Plant Nasturtium In Arizona is the key to getting vibrant blooms without scorching your plants. The desert heat can kill tender seedlings fast, so timing matters more here than in milder climates.
Nasturtiums are tough but they hate extreme heat. In Arizona, summer temperatures often exceed 100°F, which causes these flowers to wilt and stop blooming. That is why you need to work with the seasons, not against them.
This guide covers exactly when to plant, how to prepare your soil, and what to expect month by month. You will also find tips for containers, companion planting, and dealing with common pests. Let us get started.
Why Timing Matters In Arizona
Arizona has a unique climate with low humidity and intense sun. Unlike other states where you can plant nasturtiums in late spring, Arizona requires a different schedule. The plant prefers temperatures between 55°F and 75°F. Anything above 85°F stresses it out.
Planting too early in fall can expose seeds to lingering summer heat. Planting too late in spring means the flowers will face scorching June temperatures before they mature. The goal is to give them a solid 6 to 8 weeks of mild weather.
Understanding Arizona’s Growing Zones
Arizona spans USDA zones 4b to 10b. Most of the populated areas like Phoenix, Tucson, and Mesa are in zones 9a to 10b. Higher elevations like Flagstaff are cooler. The planting window shifts depending on where you live.
- Low desert (Phoenix, Tucson): Fall planting from September to November. Spring planting from February to March.
- High desert (Prescott, Sedona): Fall planting from August to October. Spring planting from April to May.
- Mountain areas (Flagstaff, Show Low): Fall planting is risky due to early frost. Spring planting from May to June.
Check your local frost dates. In the low desert, the first frost usually arrives in December, but some years it comes later. In higher areas, frost can hit as early as September.
Best Time To Plant Nasturtium In Arizona
The Best Time To Plant Nasturtium In Arizona is during the transition periods between extreme heat and cold. For most of the state, that means two windows: fall and early spring. Each has its own advantages and challenges.
Fall Planting Window
Fall is the most reliable season for nasturtiums in Arizona. The soil is still warm from summer, which helps seeds germinate quickly. The air cools down gradually, giving plants a long, gentle growing period.
- Start seeds indoors 4 weeks before your planned outdoor planting date. This protects them from lingering heat.
- Transplant seedlings outdoors when night temperatures stay above 50°F. In Phoenix, that is usually mid-October.
- Water deeply but infrequently. Fall rains sometimes help, but do not rely on them.
- Expect blooms from November through March, depending on your location.
Fall-planted nasturtiums often produce larger flowers because they have more time to establish roots. The cooler nights also encourage more vibrant colors.
Spring Planting Window
Spring planting is trickier but possible. The key is to plant early enough so that flowers appear before the heat arrives. In the low desert, that means planting in February or early March.
- Use shade cloth for the first few weeks if temperatures spike unexpectedly.
- Choose a location that gets morning sun and afternoon shade.
- Mulch heavily around the base to keep soil cool.
- Water more frequently than fall plants because spring winds dry out soil fast.
Spring-planted nasturtiums usually bloom from April to June. After that, they will start to fade. You can let them go to seed and collect seeds for fall planting.
How To Plant Nasturtiums Step By Step
Planting nasturtiums is straightforward, but a few steps make a big difference in Arizona. Follow this process for the best results.
Choose The Right Variety
Not all nasturtiums handle Arizona heat equally. Dwarf varieties like ‘Alaska’ or ‘Empress of India’ are more compact and tolerate heat better. Trailing varieties like ‘Jewel Mix’ work well in hanging baskets where they stay cooler.
Avoid giant varieties like ‘Tall Trailing Mix’ unless you have a shaded spot. They need more water and can get leggy in the sun.
Prepare The Soil
Nasturtiums prefer poor to average soil. Too much nitrogen makes them produce leaves instead of flowers. In Arizona, many soils are alkaline and sandy. That is actually fine for nasturtiums.
- Do not add compost or fertilizer. Rich soil leads to lush foliage and few blooms.
- If your soil is heavy clay, mix in some sand or perlite to improve drainage.
- Test the pH. Nasturtiums prefer slightly acidic to neutral soil (6.0 to 7.5). Arizona soil is often above 7.5. You can lower pH with sulfur or peat moss.
Sow Seeds Or Transplants
Seeds are cheaper and easier. Nasturtium seeds are large and easy to handle. Soak them in water for 12 hours before planting to speed up germination.
- Plant seeds 1/2 inch deep in the soil.
- Space them 10 to 12 inches apart. Dwarf varieties can be closer.
- Water gently after planting. Keep soil moist but not soggy.
- Seeds germinate in 7 to 14 days at soil temperatures between 60°F and 70°F.
If you use transplants, harden them off for a week before moving them outside. Place them in a shaded spot first, then gradually expose them to more sun.
Watering Tips For Arizona
Watering is the most critical part of growing nasturtiums in Arizona. Overwatering causes root rot. Underwatering causes wilting and leaf drop.
- Water deeply once or twice a week, depending on temperature and soil type.
- Check soil moisture by sticking your finger 2 inches deep. If it feels dry, water.
- Water in the morning to reduce evaporation and prevent fungal diseases.
- Use drip irrigation or a soaker hose to keep water off the leaves.
During heat waves, increase watering frequency but reduce the amount each time. This keeps roots cool without drowning them.
Companion Planting With Nasturtiums
Nasturtiums are excellent companion plants in Arizona gardens. They repel aphids, whiteflies, and squash bugs. They also attract pollinators like bees and butterflies.
Best Companion Plants
- Tomatoes: Nasturtiums deter aphids that attack tomato plants.
- Cucumbers: The strong scent of nasturtium leaves masks cucumber plants from pests.
- Radishes: Nasturtiums attract flea beetles away from radish leaves.
- Lettuce: Nasturtiums provide shade for lettuce in hot afternoons.
Plants To Avoid
Do not plant nasturtiums near beans or peas. Nasturtiums can attract black bean aphids, which spread to legumes. Also avoid planting them near fennel, which inhibits growth of many plants.
Container Gardening For Nasturtiums
Containers give you more control over soil and watering. In Arizona, pots also let you move plants to shade during extreme heat.
Choosing A Pot
Use a pot that is at least 8 inches deep and 10 inches wide. Nasturtiums have shallow roots but they spread out. Terra cotta pots dry out fast but keep roots cool. Plastic pots retain moisture but can overheat in direct sun.
Add drainage holes. Nasturtiums hate sitting in water. If your pot lacks holes, drill some yourself.
Soil Mix For Containers
Use a lightweight potting mix. Avoid garden soil, which compacts in pots. Mix in some sand or perlite for drainage. Do not add fertilizer.
For hanging baskets, use a trailing variety. The flowers will spill over the edges, creating a beautiful display. Water hanging baskets more often because they dry out faster.
Common Problems And Solutions
Even with perfect timing, nasturtiums can face issues in Arizona. Here are the most common problems and how to fix them.
Yellow Leaves
Yellow leaves usually mean overwatering or poor drainage. Let the soil dry out before watering again. If the problem persists, check for root rot. Remove affected leaves and reduce watering frequency.
No Flowers
Too much nitrogen is the usual cause. Stop fertilizing. If you used compost, remove the top layer of soil and replace it with plain sand or perlite. Also check sunlight. Nasturtiums need at least 6 hours of sun daily to bloom.
Pests
Aphids love nasturtiums. In fact, many gardeners plant nasturtiums as a trap crop to lure aphids away from vegetables. If aphids become too many, spray them off with a strong stream of water. You can also use insecticidal soap.
Whiteflies are another problem. Hang yellow sticky traps near the plants. Neem oil works well too.
Leggy Growth
Leggy stems mean the plant is stretching for light. Move it to a sunnier spot. If it is already in full sun, the problem might be overcrowding. Thin out some stems to improve air circulation.
Harvesting And Using Nasturtiums
Nasturtiums are edible. Both leaves and flowers have a peppery flavor similar to watercress. They add color and spice to salads, sandwiches, and garnishes.
When To Harvest
Pick flowers when they are fully open. Pick leaves when they are young and tender. Older leaves become tough and bitter.
Harvest in the morning after dew dries. This is when the flavor is strongest. Rinse gently and pat dry. Use them within a day for best quality.
How To Use
- Add flowers to salads for a pop of color.
- Stuff flowers with cream cheese or goat cheese for an appetizer.
- Use leaves as a substitute for arugula in sandwiches.
- Pickle the seed pods as a substitute for capers.
To pickle nasturtium seeds, collect green pods after flowers fade. Soak them in salt water for 24 hours, then rinse. Pack them in a jar with vinegar, garlic, and dill. Refrigerate for a week before using.
Extending The Blooming Season
With careful planning, you can have nasturtiums blooming for months in Arizona. Here are strategies to stretch the season.
Succession Planting
Plant a new batch of seeds every 3 to 4 weeks during the growing window. This ensures that as one batch fades, another starts blooming. In fall, plant seeds in September, October, and early November.
Deadheading
Remove spent flowers regularly. This encourages the plant to produce more blooms instead of setting seed. Use scissors or pinch off the flower stem at the base.
Shade Management
As temperatures rise, provide afternoon shade. Use shade cloth with 30% to 50% light reduction. You can also plant nasturtiums near taller plants that cast shade during the hottest part of the day.
Frequently Asked Questions
Can I Plant Nasturtiums In Summer In Arizona?
Summer planting is not recommended. Temperatures above 90°F cause seeds to fail and seedlings to wilt. If you must try, plant in a shaded spot and water twice daily. Expect low success rates.
How Long Do Nasturtiums Bloom In Arizona?
Fall-planted nasturtiums bloom from November through March, about 4 to 5 months. Spring-planted ones bloom from April to June, about 2 to 3 months. The bloom period depends on weather and care.
Do Nasturtiums Come Back Every Year In Arizona?
Nasturtiums are annuals in most of Arizona. They complete their life cycle in one season. However, they self-seed easily. If you let some flowers go to seed, new plants may appear next season without replanting.
What Is The Best Soil For Nasturtiums In Arizona?
Poor, well-draining soil is best. Avoid rich soil or fertilizer. Sandy loam with a pH between 6.0 and 7.5 works well. If your soil is heavy clay, amend it with sand or perlite.
Can I Grow Nasturtiums Indoors In Arizona?
Yes, but they need bright light. Place them near a south-facing window or under grow lights for 12 to 14 hours daily. Use a pot with drainage and water sparingly. Indoor nasturtiums may not bloom as profusely as outdoor ones.
Final Tips For Success
Nasturtiums are forgiving plants, but Arizona’s climate demands attention. Stick to the fall and spring planting windows. Water wisely. Avoid fertilizer. With these steps, you will enjoy bright, peppery blooms for months.
Remember that each microclimate in Arizona is different. What works in Phoenix might not work in Flagstaff. Observe your garden and adjust accordingly. Keep a gardening journal to track planting dates and weather patterns.
If you are new to Arizona gardening, start with a small patch or a single container. Nasturtiums are a great way to learn the rhythms of the desert. They reward you with color, flavor, and a sense of accomplishment.
Now you know the best time to plant nasturtium in arizona. Get your seeds ready for the next planting window. Your garden will thank you.