Idaho Falls Community Garden Association

Transplanting your Tomatoes

You’ve done all the preparation and have a house full of stocky, healthy, lushly green tomato plants. (Or you’ve purchased some great looking plants from your favorite garden center.) Now it’s time to get them out where they will spend the summer. Get ready to collect your reward - sweet, succulent, vine-ripened, homegrown ‘maters.  First some basics:

Tomato Growth Requirements
Like most fruits and vegetables, tomatoes require at least 6 hours of direct sunlight a day. The more the merrier! Tomatoes also require warm weather -- frost will kill them. The ideal temperature for most tomatoes is in the upper 70's to low 80's during the day, with nights in the 60's. Unfortunately (at least in this instance), you live in barely Zone 4 Idaho so you will be pleased to know that tomatoes will grow and set fruit in cooler weather; they just won't be quite as productive. Keep our local temperatures in  mind when selecting tomato varieties. For example, a grower in our area would be better off planting mostly early tomatoes (those that mature in 67 days or less) and those that are bred for cooler weather. However, when selecting tomato varieties don’t be afraid to try a few that capture your interest even if they have longer growing seasons. The challenge is part of the fun!  An adequate water supply is another essential requirement for tomatoes to produce fruits; an average of an inch and a half of water per week is considered optimal in our dry climate.

Good soil is just as essential to success as good seeds. Healthy soil yields healthy plants and healthy plants will better withstand the challenges of weather, pests and disease. You will be rewarded a hundredfold for the time you invest in improving your soil.  The single most important addition you can make is organic matter in the form of compost, aged manures, cover crops and plant matter mulches. In clay soils organic matter adds nutrients, improves the texture and increases drainage.  In sandy soils organic matter adds nutrients, improves the water holding capacity and stabilizes the soil structure. It also encourages the living network of microorganisms that are essential to healthy soil and plants. With regular attention to your soil you can expect to see yearly improvements in the tilth and fertility of your soil that will be reflected in stronger, healthier and, therefore, more beautiful and productive plants.

Studies have shown that mulching has many desirable benefits. Mulching with organic materials is ideal because it builds the soil while conserving water and reducing weeds. However, because it tends to cool the soil it is probably not the best choice for warm weather crops in our climate.  My favorite is IRT plastic mulch because, in addition to warming the soil and eliminating weeds, it reflects beneficial spectra of light back on to the plants. However, any kind of opaque plastic will do the job adequately. Lay the mulch down a few days prior to transplanting to get the full warming effect. When it is time to plant cut X slits in the plastic somewhat larger than the diameter of the planting container. Give yourself enough room to do the necessary digging and refilling.

Fertilize your tomato plants after about a week; but only fertilize at 1/2 strength. Once the tomato blossoms appear, you can begin using fertilizer at 3/4 to full strength. Organic fertilizers are preferable because they tend to break down slowly, releasing their nutrients into the soil over time. By "feeding the soil" the plants become stronger and less prone to attack from insects and disease. A good organic approach would be to use a combination of compost, peat, aged manure (or the bagged varieties from the store), and organic amendments such as blood meal and bone meal to create a rich soil. With this approach, additional fertilizer is usually only necessary only once or twice a season; just after the blossoms appear, and again when a plant is laden with fruit. Good organic fertilizers for this use include fish emulsion, seaweed emulsion, and "manure tea" (manure placed in a large container, filled with water, and allowed to "steep" for about a week). Make sure to dilute any such liquid fertilizer until it is the color of weak tea; even organic fertilizers can "fry" plants if applied too heavily. The organic method of gardening also benefits the environment by not adding chemicals that can upset the balance of nature. (Chemical fertilizers work quickly, but they also leach out of the soil quickly.)  If you’re buying prepared organic fertilizers look for those with a higher phosphorus (middle) number. Phosphorus is what fuels the production of flowers, and flowers are how fruits are formed. Try to find a relatively balanced mix (5-10-5 would be ok, 5-10-8  would be better).

Tomato Planting Instructions
If you've purchased seedlings, or if you've grown your own, here are the steps for transplanting the tomatoes. You'll need:

· shovel or trowel
· soil amendments (compost, aged manure, etc.)
· for larger tomato plants, a "cage" or a post (to help keep the tomatoes off the ground)
· mulch
· your hardened-off tomato plants.

Begin by thoroughly preparing the bed where your plants will be planted. Work the soil at least a foot deep and add organic matter to the top few inches at least 2-3 weeks before planting.

The plant spacing will be determined by the type of tomato and whether or not you intend to stake or cage them. The most space is required by an un-pruned indeterminate which will require about 3’ in all directions. Pruned and staked indeterminates can be planted from 1½ -2’ depending on the degree of pruning and staking. Determinates can generally be planted 1 - 1 ½’ apart. However, widely spaced plants of all types will be less susceptible to several diseases.

Water the plants with a diluted fish emulsion thoroughly the day before you plan to transplant so the soil will hold together on the roots. Dig a hole deep enough to accommodate your plant up to its first healthy leaf + 4”. Place amendments in the bottom 4”of the hole.  Spread your fingers and span the stem of the plant, touching the top of the seedling container. Turn the container upside-down and gently tap the container until the tomato plant comes out. Place the plant deeply in the ground - up to its first set of healthy leaves. Add soil until full, gently firming the soil around the plant. Place the cage or the post in place. Give it a good drink of water, and add more soil, if necessary.

If mulching, (remember, mulch prevents weeds, regulates the moisture in the soil, and also helps to control soil-borne bacteria) you can either plant the tomatoes first and then fit the mulch over the plants by cutting slits in the material and sliding the mulch into place or you can put the mulch in place first and do your planting through the slits in the plastic.

Drip irrigation does the best job of getting the water where it needs to be without wetting the leaves of the plant. However, you can also drench, flood irrigate or sprinkle, generally without problems. If using a method that wets the leaves try to water in the morning so that the leaves are dry by nightfall. 1-1½” of water per week is necessary for good growth.

While we have few tomato pests here in Idaho there are a couple of diseases which can cause problems. Verticillium wilt rears its ugly head occasionally but can be largely avoided with good soil health and rotated plantings. Late blight is a wind-born virus that is best dealt with by cultural methods: Don’t plant your tomatoes so closely that they create a dense moist canopy that is ideal for culturing any late blight spores that show up. Carefully monitor plants if late blight is known to be in your area and remove and burn any infected plants at the first sign of damage. For more information on late blight visit the I.F. Community Garden web site at

Thanks to the Homegrowntomatoes Internet site for the basic outline of this material.

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