Can You Start Nasturtium Seeds Indoors? A Gardener’s Guide
Yes, you can start nasturtium seeds indoors, though it’s generally not recommended due to their sensitivity to transplanting; direct sowing offers better success rates for these fast-growing flowers.
The Allure and Challenges of Nasturtiums
Nasturtiums, with their vibrant blooms and peppery leaves, are a delightful addition to any garden. Not only are they beautiful and edible, but they also act as excellent companion plants, deterring pests and attracting beneficial insects. However, starting them indoors presents a unique set of challenges. While technically feasible, the delicate root systems of nasturtiums make them susceptible to transplant shock, potentially hindering their growth or even causing them to fail.
Benefits of Starting Indoors (Despite the Risks)
Despite the challenges, there are some scenarios where starting nasturtium seeds indoors might be desirable:
- Extending the growing season: In regions with short summers, starting nasturtiums indoors can give them a head start, allowing you to enjoy blooms earlier in the season.
- Protecting from early pests: Indoor growing provides a safe haven from slugs and other early-season pests that could damage young seedlings.
- Controlled environment: Indoor conditions offer greater control over temperature, light, and moisture, which can be advantageous for germination, especially if outdoor conditions are unpredictable.
The Step-by-Step Process of Starting Nasturtiums Indoors
If you decide to start nasturtiums indoors, follow these steps carefully to minimize transplant shock:
- Choose the Right Container: Opt for biodegradable pots, such as peat pots or coconut coir pots. These can be planted directly into the ground, minimizing root disturbance. Alternatively, use individual cells in a seed starting tray.
- Use Well-Draining Seed Starting Mix: Nasturtiums prefer well-draining soil. Avoid using garden soil, which can be too heavy and compact.
- Sow Seeds Properly: Sow seeds about 1/2 inch deep and 1 inch apart in each pot or cell.
- Maintain Consistent Moisture: Keep the soil consistently moist, but not waterlogged. Use a spray bottle to gently mist the soil.
- Provide Adequate Light: Place the seedlings under grow lights or in a bright, sunny window. Rotate the pots regularly to ensure even growth.
- Harden Off Seedlings: Before transplanting, gradually acclimate the seedlings to outdoor conditions over a period of 7-10 days. This process, known as hardening off, involves exposing the plants to increasing amounts of sunlight and wind.
- Transplant Carefully: When transplanting, handle the seedlings with extreme care. If using biodegradable pots, plant the entire pot directly into the ground. If using non-biodegradable pots, gently remove the seedlings, trying to keep the root ball intact.
Common Mistakes to Avoid
- Overwatering: Nasturtiums are susceptible to root rot if the soil is constantly waterlogged.
- Starting too early: Starting seeds too early can result in leggy, weak seedlings that are more prone to transplant shock.
- Disturbing the roots during transplanting: This is the biggest threat to successful indoor starting of nasturtiums.
- Not hardening off: Failure to harden off seedlings can result in sunburn and stunted growth.
- Using poorly draining soil: Heavy, compacted soil can suffocate the roots.
Comparing Indoor Starting vs. Direct Sowing
| Feature | Starting Indoors | Direct Sowing |
|---|---|---|
| Transplant Shock | High risk | No risk |
| Germination Time | Slightly faster (potentially) | Dependent on soil temperature |
| Control | Greater control over environment | Less control over environment |
| Best For | Regions with short summers or pest problems | Most regions with suitable growing conditions |
| Root Disturbance | High risk | None |
Soil and Light Requirements
Nasturtiums thrive in well-draining soil that is not overly fertile. In fact, rich soil can lead to abundant foliage but fewer flowers. A slightly acidic to neutral pH is ideal. They prefer full sun to partial shade, with at least 6 hours of sunlight per day.
Frequently Asked Questions (FAQs)
What is the ideal temperature for germinating nasturtium seeds indoors?
The ideal temperature for germinating nasturtium seeds indoors is between 65-75°F (18-24°C). You can use a heat mat to maintain a consistent temperature, especially if your home is cool. However, avoid overheating the seeds, as this can also inhibit germination.
How long does it take for nasturtium seeds to germinate indoors?
Nasturtium seeds typically germinate within 7-14 days when sown indoors under optimal conditions. Ensure adequate moisture and warmth to encourage successful germination. Soaking the seeds overnight before planting can speed up the germination process.
What kind of soil should I use for starting nasturtium seeds indoors?
Use a well-draining seed starting mix. Avoid using garden soil, as it can be too heavy and compact, hindering root development. A mix of peat moss, perlite, and vermiculite is a good option. Remember nutrient-rich soil is unnecessary, and can even be detrimental, as nasturtiums bloom best in slightly poorer soils.
How often should I water nasturtium seedlings indoors?
Water nasturtium seedlings regularly, keeping the soil consistently moist, but not waterlogged. Allow the top inch of soil to dry out slightly between waterings. Overwatering can lead to root rot, so it’s important to strike a balance.
Do I need to fertilize nasturtium seedlings indoors?
Generally, no. Nasturtiums don’t require much fertilizer, especially when grown indoors. Excessive fertilization can promote foliage growth at the expense of flowers. If needed, use a very diluted balanced liquid fertilizer sparingly.
How do I harden off nasturtium seedlings before transplanting?
Harden off nasturtium seedlings by gradually exposing them to outdoor conditions over a period of 7-10 days. Start by placing them in a sheltered location for a few hours each day, gradually increasing the amount of sunlight and wind exposure. This process helps them acclimate to the outdoor environment and reduces transplant shock.
What is transplant shock, and how can I minimize it when transplanting nasturtiums?
Transplant shock occurs when plants experience stress from being moved from one location to another. To minimize transplant shock in nasturtiums, handle the seedlings with extreme care, avoiding any disturbance to the roots. Use biodegradable pots, transplant on a cloudy day, and water thoroughly after transplanting. Minimizing root disturbance is key.
Can I grow nasturtiums in containers?
Yes, nasturtiums are well-suited for container gardening. Choose a container that is at least 6 inches deep and wide. Use a well-draining potting mix and provide regular watering and sunlight. Trailing varieties look particularly stunning in hanging baskets.
What are the best companion plants for nasturtiums?
Nasturtiums are excellent companion plants for vegetables such as tomatoes, cucumbers, and cabbage. They attract beneficial insects and deter pests like aphids and whiteflies. Planting them near beans and brassicas is highly recommended.
How do I collect seeds from nasturtiums?
Allow the seed pods to dry on the plant until they turn brown and papery. Once dry, collect the seeds and store them in a cool, dry place. Nasturtium seeds are easy to save and can be used for planting in subsequent years.
Are all parts of the nasturtium plant edible?
Yes, all parts of the nasturtium plant are edible, including the leaves, flowers, and seed pods. The leaves and flowers have a peppery flavor, while the seed pods can be pickled and used as a substitute for capers. They are a delicious and nutritious addition to salads and other dishes.
What pests and diseases affect nasturtiums, and how can I prevent them?
Nasturtiums can be susceptible to aphids, spider mites, and whiteflies. Regularly inspect the plants for pests and treat them with insecticidal soap or neem oil if necessary. Good air circulation and proper watering can help prevent fungal diseases. Companion planting and maintaining healthy soil are also effective preventative measures.