Container Gardening

Next to regular watering, the most important part of container gardening is fertilizing.  In the ground, plants can pull nutrients from the dirt, slowly and steadily.  A container, on the other hand, is a closed system: nothing goes in but what you put in.  This means that if you want healthy vegetable plants, you have to supply the fertilizer to keep them healthy.

So, what is fertilizer?  Fertilizer is a combination of basic nutrients and minerals which plants need to survive.  Fertilizing your plants regularly works like vitamin pills do for people: they provide balance to a diet that is almost certainly inadequate to start.

There are three main nutrients that plants need: nitrogen, phosphorus, and potassium.  A complete fertilizer will contain all three of these nutrients.  A balanced formula contains all three in equal amounts.  Depending on what you are growing, you will want different proportions of these nutrients.

Nitrogen is used by plants to build healthy foliage.  It is critical for all vegetables, but especially important in vegetable container gardens where you are focusing on leafy vegetables.  Lettuces, spinach, etc, would want a fertilizer that focuses on nitrogen.

Phosphorus is used by plants to produce healthy flowers and fruits.  Tomatoes, peppers, squash, and the like will need more phosphorus, especially when they are ready to shift from growing leaves to growing fruit.  When growing tomatoes, it can be useful to add a phosphorus booster at this stage to assist them in moving to fruiting.

Potassium helps build healthy roots in all plants.  Generally, the healthier the roots, the healthier the plant, so keeping the potassium level where it should be can prevent many plant problems.

Every commercial formula will tell you, somewhere on the packaging, what the proportion of the nutrients is to each other.  It is the proportion that matters in fertilizer, not the absolute amount: you will need to dilute fertilizer to use it.

To tell the proportion of these nutrients in a commercial fertilizer, look for a series of three numbers on the label.  This is the N-P-K number, viewed in the form 10-20-10.  The numbers represent the percentage of the fertilizer that is, respectively, nitrogen, phosphorus, and potassium.  The numbers are always written in that order.

In addition to the three major nutrients, your plants need a collection of lesser nutrients.  These include calcium, magnesium, sulfur, iron, manganese, copper, chlorine, boron, zinc, and molybdenum.  A good all-around commercial fertilizer will contain all of these in trace amounts.  If you ever find your plant struggling, and cannot tell why, applying a mix of these trace elements to your plants may help them revive.

I generally start my planting with a potting mix that comes pre-fertilized.  This means the mix has a fertilizer mixed in which is released slowly by watering.  Over the course of a few months, the plants will unlock and consume that fertilizer.  On top of that fertilizer, it’s a good idea to fertilize every week or two weeks according to the instructions on your fertilizer.

Be careful not to over-fertilize!  Many of the substances found in a standard fertilizer, including the main nutrients, can actually damage plants if overused.  Keep to the standard schedule unless your plants seem to be struggling.

Under normal circumstances, summer squash will thrive on their own. Occasionally, however, you will need to help them along. If your plants are too well sheltered from wind and insects to pollinate on their own, this help may extend to hand-pollinating your squash.

The first question, when growing squash, is whether hand-pollination is necessary. Your squash will not produce fruit under any circumstances if it does not have both male and female flowers on it yet. Just having a number of flowers does not guarantee that you have both male and female flowers: growing squash plants often produce many male flowers before producing their first female flower.

Distinguishing male flowers from female is fairly simple. Male flowers grow directly from a stem. Female flowers have a little fruit between the stem and the flower, from which a full squash will form if the flower is pollinated. If you have both male and female flowers, but none of the little fruits on the female flowers are maturing, you may need to help nature along.

There are two ways to hand-pollinate your squash.  It’s always best to hand-pollinate early in the morning, when the flowers are open.

The first method is simplest: pick the male flower and remove all petals from it.  You will be left with the stamen of the flower, a little yellow spike covered lightly with pollen, which looks like yellow dust.  Touch the stamen to the center of a female flower.  Leave the female flower to ripen into a squash.

The second method is a bit more complicated, but leaves the male flowers intact, in case you want them for either ornamentation or eating (you can eat squash flowers either plain or lightly cooked).  Instead of picking the flower and directly touching the stamen to the female flower, you will play insect.  Using a cotton swab, lightly touch the stamen of a male flower, picking up a bit of the pollen.  With the cotton swab, brush the center of the female flower, transferring the pollen over.  This is the same way that bees pollinate plants, by moving from flower to flower, bringing a residue of pollen along with them.

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!