Container Gardening

When I went to my mother’s house yesterday, I found her (in-ground) tomatoes suffering from a fairly severe case of early blight.  In my part of the world (Massachusetts), this has been an extremely wet June, leading to some delays in vegetable growth and some fun and exciting health problems for our plants.  Inspired, I’ve decided to talk about early blight in container tomatoes.

As with most vegetable diseases, this is more common with in-ground plants than it is with vegetables grown in pots.  Most plant diseases incubate in the soil, and the soil for in-ground vegetable gardens is more likely to be contaminated than the soil in containers, especially if you use fresh potting mix every year for your container garden.

However, the fact that it’s more common with in-ground tomatoes doesn’t mean you don’t see it when growing containers in pots.  So, what is early blight?

Early blight is a fungal infection that can affect eggplant, pepper, potato, and tomato plants.  It tends to do the most damage to potato and tomato plants.  It survives between hosts in the soil, living off the plant matter in the dirt.

Early blight can affect the leaves, the stem, and the fruit of tomato plants.  The symptoms vary depending on what part of the plant you are looking at.

Leaf Lesions

The first place you usually spot early blight is on the oldest leaves, near the bottom of the plant.  It will show as brown blotchy spots, surrounded by a yellow halo.  Eventually, the yellow will overtake the entire leaf, and it will wither and die.

If the damage spreads to the stem, it will show as dark, elongated patches on the stem.  Fruit can also be affected, with dark sunken lesions on the fruit.  These are leathery to the touch, and usually occur at the stem end of the fruit.

If you catch early blight when it first appears, it is usually correctable.  Early blight spreads up the plant from the lowest affected leaves, so when you see leaves with the characteristic lesions, remove them immediately.  Damaged stems will eventually kill off any plant growing beyond them, so if you have main stem damage, it is best to pull the entire plant and start over.  Any affected fruits should be picked and thrown away, letting the plant focus its energy on healthy tomatoes.

You can use a mild fungicide to catch early cases of blight.  Organic gardeners find that a milk spray (one part milk to 10 parts water, misted on the plant after every rain), helps prevent fungal infections or treat existing ones.

Preventing blight is usually easier than fixing it, however.  The most common way for tomatoes to develop blight is from infected soil splashing up onto their lower leaves.  To prevent this, make sure to tie up all leaves that hang close to the ground.  You can trim the lower branches entirely as the plant grows: these won’t get as much sun and will not thrive anyway.

You can also mulch over your soil, creating a barrier between the dirt and the plant.  This has the added benefit of keeping the soil more moist between watering sessions, which is always a challenge for container gardeners.

I first heard about growing cherry tomatoes in hanging baskets two years ago, when I was at my local farmer’s market. One of the booths was selling pre-planted hanging baskets with cherry tomatoes for some exorbitant amount of money: $25 or so, I think. I was tempted in spite of the high price: I love fresh cherry tomatoes, and these were beautiful plants, with gorgeous tangles of vines and cascading fruits. In the end, though, I decided against it.

It turns out, though, that it’s easy to create your own hanging baskets for cherry tomatoes, and for much less money than the farmers were asking. Here are some tips to get you started.

The first step, as with most container gardening, is to choose the container. Just about any garden center or hardware store will sell simple wire hanging baskets such as the one shown in this ad, which are cheap and practical. Many come prelined with coconut coir, but if yours doesn’t, it’s easy to find and purchase liners. You can usually find baskets like this for under $10. It’s a good idea to get one a minimum of 12″, and 14″ is better. Still, you can grow cherry tomatoes in smaller baskets, if you choose your variety carefully.

Once you have your container, you can choose a cherry tomato to plant in it. My article on best container cherry tomato varieties has information about good varieties of cherry tomatoes for growing in baskets. You can either grow your cherry tomato from seed and transplant it into the basket, or buy the seedlings direct. It is not a good idea to plant seeds directly in your hanging basket.

Once you have a good-sized cherry tomato seedling, you will need to plant it. You do not want to use soil for planting in baskets. Choose either a good soilless potting mix or a medium of sphagnum moss. Soilless growing media hold water much better, which is very important when working with small containers such as hanging baskets.

Fill the basket around halfway with the potting mix, then set the seedling in the basket. When growing cherry tomatoes, it’s a good idea to plant it deeply: tomato plants can form roots along their main stems, so the root system will develop more quickly if part of the stem is buried. Once the seedling is placed, fill the basket in the rest of the way. Water heavily. Soilless planting media will hold a great deal of water, which is why they’re so good for containers.

When choosing a place to hang your cherry tomato basket, make sure it is a sunny location. Growing cherry tomato plants need a lot of sun. As a minimum, they should get six hours a day, and more is better. Also consider placement: you want easy access to the plant, so you can water it and harvest from it.

Your plants will die each year with the frost, but the baskets are reusable each year with a fresh liner. Enjoy your cherry tomatoes!

Whenever you start reading about growing tomatoes in pots, you’re almost certain to start encountering talk about determinate and indeterminate tomatoes. What do these terms mean? What can you expect from a determinate tomato, or an indeterminate one?

The simplest answer is that determinate tomatoes set their fruit all at once, whereas indeterminate tomatoes continue to grow and produce fruit until they are killed — usually by frost.

This definition has some other implications, however, which need to be considered.

If you watch the growth of determinate tomatoes, you’ll see a set pattern: the tomato plants grow until they reach a certain size. Then, all at once, the plant flowers. Flower occur at the tips of stems, ending growth. Then the flowers fruit, and ripen. There are some determinate tomatoes, called “vigorous determinate”, that will produce a second crop if you prune them back after the first harvest is done. Celebrity is probably the most well-known of the vigorous determinate varieties.

Indeterminate tomatoes, on the other hand, produce flowers and fruit steadily throughout the season. Branches form flowers along the side, so new growth continues constantly from the end of the vines. Because of this, the fruit crop is slower and steadier.

Because of their pattern of growth, determinate tomatoes grow very well in containers. They do not grow out of control, and require less staking than indeterminate varieties. However, if what you want is a steady supply of tomatoes for salads and the like, determinate tomatoes probably won’t suit your needs. The extra work of container growing indeterminate tomatoes may be worthwhile in that case.

So, if you want to grow indeterminate tomatoes in a container, what do you need to do?

Well, the first step, as always, is to choose the container. Choose large, for indeterminate tomatoes: 6-7 gallons, to support a large plant.

Install a cage when you plant the seedlings, and make sure it is tall: some indeterminate tomatoes will grow to six or seven feet tall.

As tomato vines reach outside the cage, tie them to the cage or prune them off. You need to check the growth, because it will eventually get out of control otherwise. I talk a bit more about pruning in 7 Tips for Great Tomatoes.