Nasturtiums, known for their vibrant, edible flowers and peppery leaves, are popular annuals. Despite being hardy, these plants have a strong reputation for failing to thrive when moved after initial planting. This poor success rate leads experienced growers to avoid transplanting them, preferring methods that bypass moving a growing seedling. The difficulty in moving nasturtiums is a direct result of their specific root structure and sensitivity.
Why Nasturtiums Resist Transplanting
The primary reason nasturtiums struggle after being moved is their delicate and deep root system. Unlike many annuals that develop a fibrous root ball, nasturtiums typically form a long, sensitive taproot. This central, downward-growing root is the plant’s main anchor and water source, making it highly susceptible to damage.
Even a slight disturbance or break in the taproot during relocation can cause significant shock. When the taproot is compromised, the plant’s ability to draw up water and nutrients is hindered, leading to rapid wilting and failure to establish itself. The plant expends energy trying to recover, which often stalls or prevents future growth and flowering.
The Preferred Method: Direct Sowing
Given their aversion to root disturbance, the optimal method for cultivating nasturtiums is direct sowing. This involves planting the seeds directly into the final location where they are intended to grow. Timing is generally one to two weeks after the last expected spring frost, when the soil temperature has warmed consistently to 55°F–65°F.
The large seeds are typically sown about a half-inch deep into the prepared soil. While pre-treatment is not strictly required, gently scratching the hard outer seed coat (scarification) or soaking the seeds overnight can help speed up germination. Plant the seeds approximately 10 to 12 inches apart to provide ample room for growth, especially for sprawling or climbing varieties.
Mitigation Strategies for Necessary Moves
While direct sowing is recommended, moving a small plant or starting nasturtiums indoors is sometimes unavoidable. In these cases, the focus must be on minimizing root disturbance. Starting seeds in biodegradable pots, such as peat or coir pots, is the most effective strategy.
The entire pot, with the seedling inside, can be placed directly into the ground. This allows the roots to grow through the material without being exposed or handled. If the plant must be removed from a container, do so when the seedling is very young, ideally when it has developed only its first set of true leaves. When lifting the plant, water it well the day before. Then, carefully dig a generous perimeter to ensure the entire root ball remains intact as it is moved.
Immediate Care Following Relocation
The first 24 to 48 hours after relocation are the most significant for the nasturtium’s survival. Immediately after placing the plant, deep watering is required to settle the soil around the root ball and drive out air pockets. This initial soaking reduces the risk of transplant shock by ensuring good contact between the roots and the surrounding soil.
Providing temporary shade for the first day or two is also beneficial. This reduces the moisture the leaves lose through transpiration while the roots establish themselves. Avoid applying fertilizer during this recovery period. Nasturtiums prefer poor soil, and the addition of nitrogen can stress a newly moved plant. Resume normal care only after the plant shows clear signs of having successfully established itself.