Question
Hi Mike

The leaves of some of my nice green plants with lots of foliage and budding tomatoes are suddenly curling upwards and then inwards with a vengeance...would you have any ideas why?  The weather hasn't been too strange; it's been consistently warm (approx 29 - 35 degrees celsius every day), they're in containers, and I've been watering them steadily every morning (they're usually reasonably dry by end of day).  If I stand back and look at the plant now, it actually looks a bit sickly, with leaves turned and curled in various ways.   

The lower leaves of the plants are also turning very yellow - I've heard that this is normal, but should I take them off the plant?  

Thanks

Answer
Overfertilizing, especially with a high nitrogen fertilizer such as standard Miracle-Gro, can cause the type of symptoms you have described.  The high nitrogen levels can adversely affect the foliage on young seedlings and the high salt content in most synthetic fertilizers can result in root burn.  My advice, especially while the plants are still young, is to fertilize once every 14 days at half strength to prevent excess salt buildup in the soil.

Another option is to purchase a water soluble fertilizer recommended specifically for tomatoes.  Miracle-Gro makes such a product, as does Peter抯 and Schultz.  These tend to be higher in phosphorus and potassium which are essential for good production and larger fruits.

Overwatering can definitely cause leaf curl on tomatoes. This is especially prevalent when using containers with poor drainage.  The result is poor root development, and nutrients being leached from the soil.  Make sure you supplement the plants with 1.5?of water per week by watering very deeply once or twice per week.  More may be required during periods of drought.  Shallow watering causes the roots to reach for the surface instead of deep into the soil.  The result is weakened plants with little or no harvest.

One other possibility is that plant has become root bound. Tomatoes should be transplanted twice to larger pots prior to planting in the garden. They are one of the few plants that actually thrive when transplanted. They also should be planted several inches deeper each time.  This allows the bottom of their stems to produce root nodules that result in a stockier and stronger plant.  It will also aid in increasing the harvest once the plant begins producing.

Finally, make sure the plants are well mulched with either straw or aged grass clippings.  This will help retain moisture while keeping the roots cool.  Next year, work in as much organic matter as possible to the soil.  This would include humus, compost, and manure.  And make sure you rotate the plants using a three year cycle to prevent soil borne diseases from affecting next year抯 plants.

The good news is that this condition normally corrects itself.  Use the techniques I described above and the problem should disappear shortly.

I hope this answered your question.  Please write again if I can ever be of assistance.

Regards,

Mike