Free Guide to Growing Nasturtium Flowers

Understanding Nasturtium Plants and Their Growing Conditions

Nasturtiums are flowering plants known for their bright, cheerful blooms in shades of red, orange, and yellow. These plants belong to the genus Tropaeolum and come from South American regions, which means they thrive in warm weather. Understanding the basic characteristics of nasturtiums helps you create the right environment for them to flourish.

Nasturtiums grow as either climbing vines or compact bush varieties, depending on the species. The climbing types can reach 6 to 10 feet in length, while dwarf varieties typically stay between 12 and 18 inches tall. Both types produce round, shield-shaped leaves and trumpet-shaped flowers that bloom throughout the growing season. The flowers are not just beautiful—they're also edible, with a peppery flavor that gardeners sometimes use in salads.

These plants prefer temperatures between 50 and 70 degrees Fahrenheit. They struggle in extremely hot conditions above 85 degrees, which can cause flower production to slow or stop entirely. Nasturtiums are sensitive to frost and cannot survive freezing temperatures, so they work best as annual plants in most climates or as tender perennials in warmer regions.

One interesting characteristic of nasturtiums is their preference for less-fertile soil. In rich, heavily fertilized soil, these plants produce abundant foliage but fewer flowers. This quality makes them an economical choice for gardeners since they don't require expensive soil amendments. Their shallow root systems make them suitable for container growing, window boxes, and hanging baskets.

Practical Takeaway: Before planting nasturtiums, assess your climate and choose a location that gets adequate sunlight. Select a climbing variety if you want vertical coverage on trellises or fences, or choose a dwarf variety for borders and containers. Remember that these plants prefer moderate conditions and won't need heavy feeding to produce flowers.

Selecting the Right Location and Light Requirements

Location is one of the most critical factors in nasturtium growing. These plants need direct sunlight to produce the maximum number of flowers. Research from university extension services indicates that nasturtiums perform best with six to eight hours of direct sunlight daily. In regions with extremely hot summers, afternoon shade during the hottest months (typically July and August in northern climates) can prevent heat stress without significantly reducing blooms.

Nasturtiums are quite adaptable regarding light conditions. They can tolerate partial shade—meaning three to six hours of direct sun—though they'll produce fewer flowers than plants grown in full sun. If you live in a region with mild summers, placing nasturtiums where they receive bright light all day will reward you with continuous blooms. In contrast, gardeners in hot climates may find that morning sun with afternoon shade produces the best overall flowering.

The direction of sunlight matters as well. South-facing and west-facing locations provide the most intense light throughout the day. In cooler climates where temperatures rarely exceed 75 degrees, these directions are ideal. East-facing locations provide gentle morning sun, which is beneficial in hot climates because it warms the plants gradually without the intense afternoon heat. North-facing locations typically provide insufficient light and should be avoided unless you're in a consistently warm climate where some shade is necessary.

Wind exposure also relates to location selection. While nasturtiums aren't fragile, strong winds can damage climbing varieties and stress all types of plants. Sheltered locations near walls, fences, or other structures provide protection while still allowing adequate air circulation. Good air movement prevents fungal diseases that thrive in stagnant, humid conditions.

Practical Takeaway: Scout your garden space and identify areas receiving six to eight hours of direct sun. If your climate is hot, prioritize areas with afternoon shade. For climbing varieties, select spots near structures that provide wind protection while allowing the plants to climb upward toward sunlight.

Preparing Soil and Planting Your Nasturtiums

Nasturtiums are not fussy about soil composition, which makes them a forgiving option for beginning gardeners. Unlike many flowering plants, nasturtiums actually perform better in poor to moderately fertile soil. This is because rich soil encourages excessive leaf growth at the expense of flowers. Soil that's too fertile may produce plants that are lush and green but produce few blooms.

The ideal soil for nasturtiums has good drainage and a pH between 6.0 and 7.0, which is neutral to slightly acidic. You can check your soil pH using an inexpensive test kit available at garden centers. If your soil tends to retain moisture, amending it with coarse sand or perlite improves drainage. Garden soil that has been used for several seasons without heavy fertilization is often perfect for nasturtiums.

Before planting, prepare your garden bed by loosening the soil to a depth of 8 to 10 inches. Remove any rocks, weeds, or debris that could interfere with root development. If your soil is particularly poor or compacted, mixing in one to two inches of compost improves structure without adding excessive nutrients. Work the amendments into the existing soil thoroughly.

When planting nasturtium seeds directly in the garden, sow them about 1 inch deep and 8 to 12 inches apart, depending on the variety. Nasturtium seeds are relatively large, making them easy to handle. They have a hard seed coat, so soaking them in warm water for a few hours before planting speeds germination. Plant seeds outdoors after the last frost date in your area. In most regions, this falls between mid-April and late May. The seeds typically germinate within 7 to 14 days in warm soil.

For container growing, use a well-draining potting mix rather than garden soil. A standard potting mixture works well, and you can make it even faster-draining by adding extra perlite. Containers should have drainage holes to prevent water from pooling around the roots. A pot that's 8 to 12 inches deep accommodates most nasturtium varieties comfortably.

Practical Takeaway: Test your soil before planting. If it's already reasonably fertile, avoid adding extra compost or fertilizer. For gardens with very rich soil, plant nasturtiums in containers or poor soil areas instead. Soak seeds overnight and plant them directly after your final frost date for the most straightforward growing approach.

Watering and Fertilizing Your Nasturtium Garden

Proper watering is essential for nasturtium success, though these plants are somewhat drought-tolerant once established. Young nasturtiums need consistent moisture while they're developing roots, but established plants prefer conditions that are slightly on the dry side. Overwatering is a more common problem than underwatering and can lead to root rot and fungal diseases.

During the growing season, water nasturtiums when the top inch of soil feels dry to the touch. In most climates, this means watering once or twice weekly during periods without rain. During hot, dry spells, you may need to water more frequently, especially for container plants. Water at soil level rather than from above to minimize disease risk. Morning watering is ideal because it allows any moisture that does splash onto leaves to dry quickly in the sun.

Container-grown nasturtiums dry out faster than garden plants and require more frequent watering. Check containers daily during hot weather. The soil should be moist but not soggy. A simple test involves inserting your finger into the soil; if it feels dry about an inch down, watering is needed.

Regarding fertilization, nasturtiums require very little feeding. In fact, over-fertilization reduces flowering and creates problems more often than it solves. If you've prepared the soil properly with minimal added nutrients, you may not need to fertilize at all during the growing season. If plants appear pale or produce very few flowers, a light application of balanced fertilizer every four to six weeks may help. Use a diluted solution at half the recommended strength to avoid encouraging excessive foliage growth.

Liquid fertilizers or diluted fish emulsion are appropriate choices for nasturtiums. High-nitrogen fertilizers should be avoided because they promote leaf growth over flowering. A fertilizer with an NPK ratio close to 10-10-10 or even lower nitrogen content is preferable. Always follow package directions and err on the side of using less rather than more.

Practical Takeaway: Water deeply but infrequently, allowing soil to dry slightly between waterings. Check container plants daily during warm weather