How to properly illuminate tomato seedlings at home Which lamps are best for additional lighting

Most heat-loving plants in the Russian climate are grown through seedlings. Tomatoes are no exception. For greenhouse varieties of tomatoes, sowing time begins in January, for placing the crop in open ground - from the end of February. During this seasonal period, there is not enough sunlight for plants to develop properly, so additional artificial lighting is required. Only experienced vegetable growers, whose recommendations are presented in the article, know how to properly illuminate tomato seedlings in an apartment.

How to properly light tomatoes at home

As mentioned above, tomatoes need additional lighting, but how to do it correctly? A novice gardener may have a lot of questions: what to add additional lighting to, how long, when to start additional lighting, etc.

If you illuminate the seedlings with an unsuitable or incorrectly installed lamp, you will only harm them.

It is also important to take into account the optimal duration of daylight hours and several other important nuances.

Basic Rules

When additionally lighting tomatoes, you must take into account several important rules:

In order for seedlings to grow and develop normally, it is necessary to observe the “day-night” regime. It is highly not recommended to provide additional lighting around the clock.
Install the lamp used for supplementary lighting at the correct distance from the plants. However, it may vary depending on the type of lamp. If the light source is placed too close to the tomatoes, then the substrate in the container will begin to dry out much faster, and this can also lead to overheating of the seedlings.

If the lamp is located higher than necessary, this will negatively affect the effect expected from additional illumination.

To ensure that the sprouts are illuminated evenly, reflective screens are used, which can be foil, white paper sheets, a mirror, metal surfaces, light-colored plastic, etc. Such screens help distribute the luminous flux of daylight more evenly. An ordinary white curtain can also cope with this role.
Seedlings that are located in dense groups are recommended to be illuminated with compact fluorescent lamps. Seedlings standing on a windowsill or shelf are illuminated with compact but powerful lamps.
Distance to leaves

To ensure that the lamps used for supplementary illumination do not harm the seedlings, but only benefit them, they should be installed at the correct distance.

To illuminate 1 m2 of tomato seedlings, lamps are used, the power of which can vary from 200 to 450 watts. It is better not to place such a light source very close to young plants, because this leads to overheating. It should be installed at a height of approximately 150 centimeters from the tomatoes.

If the lamp emits cold light, then it can be installed at a height of about half a meter.

In order to determine the optimal distance between the seedlings and the lamp, you need to place your palm under the incident light.

If you feel the heat well, then install the lamp higher. Once the light fixtures are installed, turn on another lamp. If in this case it becomes lighter, it means that you need to install an additional lighting device.

When to light up

In order for additional lighting of tomato seedlings to give the best possible result, you need to know how long daylight hours the plants need at each stage of development:

Immediately after the seedlings appear, they need to be illuminated around the clock for two to three days.
Before picking, seedlings are illuminated for 16 hours every day for 10–12 days.
When the plants are picked, until they are thirty days old, the duration of daylight hours should be 16 hours.
The duration of daylight hours for tomatoes from 30 to 60 days should be at least 14 hours.

The main rule is that daylight hours should not be interrupted. If you want to increase it, then you can turn on the additional lighting early in the morning. Or you can distribute the required additional lighting time between evening and morning.

Should I turn on the lamp at night?

It is highly not recommended to provide additional lighting to tomato seedlings around the clock. Plants need rest at night, its duration should be at least 5 hours. Thanks to this, the development of the tomato will be complete.

During the night, they must have time to process everything that the foliage has accumulated during daylight hours. If young tomatoes do not get proper rest, then they develop a deficiency of nutritional components. As a result, the color of the foliage of such bushes changes to brown, and their deformation occurs.

Dependence of illumination on the distance between the source and the illuminated surface.

Illumination on a surface is inversely proportional to the square of the distance from the lamp to the surface. If you move a lamp hanging above the plants at a height of half a meter to a height of one meter from the plants, thus doubling the distance between them, then the illumination of the plants will decrease by four times. This is something to keep in mind when you are designing a plant lighting system.

If the illumination at a distance of 1 m from a light source is 1000 lux, then at a distance of 2 m it is already 250 lux, see table

1 1000 1

2 250 4

3 111 9

4 63 16

5 40 25

6 28 36

The illumination on a surface depends on the angle at which this surface is illuminated. For example: the sun on a summer afternoon, being high in the sky, creates illumination on the surface of the earth several times greater than the sun hanging low above the horizon on a winter day. If you use a floodlight type lamp to illuminate plants, try to ensure that the light is directed perpendicular to the plants.

Which lamps to choose for supplementary illumination of tomato seedlings at home

In order for tomato seedlings to grow well, they need to be illuminated with lamps of a specific color spectrum. The best lighting fixtures are those that emit blue or red rays. Under orange-red light, seedlings will appear much faster, and this will also lead to increased growth.

Thanks to blue-violet light, plant cells begin to grow more intensively, and thanks to it, short and powerful shoots are formed.

When choosing a lighting device, you need to remember that:

it should provide the required amount of light, but at the same time it should not contribute to overheating and drying out the air.
The light needs to be soft and not irritating to the tomatoes.
the device should illuminate the plant evenly, and the rays should reach the farthest corners of the plantings.

Pros and cons of phytolamp

This type of LED lamp, the phytolamp, is very popular among summer residents.

And they are good because:

save energy consumption;
have insignificant heat transfer, which cannot affect the air temperature;
are environmentally friendly and safe (they do not emit ultraviolet radiation, which is considered very harmful);
have a good ratio of blue and red spectrum.

The phytolamp is perfect for illuminating tomato seedlings.

However, it has one drawback - it is very expensive. But due to the fact that this device saves energy, can serve for several years and provides rich tomato harvests, its cost quickly pays off.

How to provide additional lighting if there is no phytolamp

In addition to phytolamps, gardeners use the following lighting devices for additional lighting:

High pressure sodium lamps. It provides warm, stable light that has a positive effect on the growth and development of young tomatoes. However, such a device will require additional equipment, and it is also quite expensive.
Sodium metal halide elements. This device is notable for its accessibility, but it does not have enough blue light, which is why the seedlings do not develop very well.
Fluorescent lamps. Such fluorescent lamps have many advantages, but their light is still quite cold, and therefore has a poor red spectrum.

Do-it-yourself illumination of seedlings with LEDs

LED lights are becoming more and more popular with gardeners every year. And all thanks to the fact that you can easily create a lighting device from LEDs with your own hands, ideal for growing tomato seedlings. To do this, combine the 2 most important spectra: blue and red.

In order to create an LED strip light with your own hands, you need to prepare:

blue and red LEDs;
thermal paste (hot glue);
base, for example: furniture profile, piece of aluminum, etc.;
power supply or driver;
plug and cord.

When creating the ideal lighting fixture, you need to consider:

The LEDs must be mounted on the strip in the following sequence: one blue and two red elements.
They are connected to each other by soldering, after which they are brought out to the driver, and it is connected to a switch and plug.
You can attach the tape to the prepared surface with double-sided tape, bolts or rivets.
Then the lamp is assembled into a single circuit with a driver, cord, switch and plug.

Super easy! Free lighting for seedlings - video

What is better to choose according to reviews from gardeners

The most popular among summer residents are fluorescent lamps, which are quite economical and provide good results. Every year LED lamps, which are economical and do an excellent job, are becoming more and more popular.

Effect of light spectrum on plants

From our school physics course we remember that light has different wavelengths. Plants are able to distinguish between different frequencies of the spectrum and use some of them for life. Moreover, each type of spectrum will be used only for a specific purpose:

ultraviolet (blue) - will increase resistance to cold and resistance to disease;
infrared - stimulates the growth of the aboveground part;
red and purple - used in photosynthesis;

Orange color stimulates fruiting, but plants practically do not use the yellow spectrum. In rooms, lighting fixtures emit light most often in this range.

Plants need a multispectral light source to fully develop. It can be adjustable or unregulated, the main thing is that the plant receives exactly the light that it needs for proper development at the seedling stage. LED bicolor phytolamps are best suited for this. They are durable, suitable for plants and do not irritate the human eye, so they can be used for supplementary illumination of seedlings indoors.

Manufacturers usually indicate for which plants the phytolamps are intended. Follow this information, but check the emitted spectrum.

Basic care for seedlings in January, February, March

As a rule, inexperienced gardeners try to sow tomatoes as seedlings as early as possible, believing that this will allow them to get the first fruits much faster. Below we will describe the features of sowing and caring for tomato seedlings in January, February and March.

Growing in January

January is considered the most unfavorable month for sowing tomato seeds for seedlings, because at this time there is still very little sunlight, and there is still a lot of time before the plants are planted in the soil. Experienced gardeners recommend sowing tomatoes for seedlings in January only if you can illuminate them with high-power fluorescent lamps.

But in this case, it should be taken into account that even late-ripening varieties will bend under their own weight after a couple of months.

Growing seedlings in January is complicated by the fact that they need to be provided with regular additional lighting, and the daylight hours must be at least 12 hours. However, by planting such seedlings in a heated greenhouse, you can get the first fruits quite early.

Growing in February

Most gardeners are sure that it is necessary to sow tomato seeds for seedlings in February. However, experts say that it is too early to sow seeds at this time. Although there is already more light at this time than in January, the difference is not too noticeable.

As a rule, February seedlings planted in open soil will lag behind in growth and development from those seedlings that were planted later.

Growing in March

March is considered the best month for sowing seeds of such a crop for seedlings. At this time, the sun shines more brightly, and the emerging seedlings have time to grow and become stronger before they are planted in open ground.

Gardeners have noticed that March seedlings grow and develop much better and faster than winter ones.

Features of caring for seedlings

Make sure that the substrate in which the seedlings grow does not dry out, and also do not allow water to stagnate in the root system of the plants. The fact is that this can lead to their death: they will either rot or dry out.

After the formation of real leaf blades, the seedlings must be planted in individual, not very large cups. Frail, pale shoots need feeding. To do this, you can use either purchased or homemade fertilizer (infusion of bird droppings).

To prevent grown seedlings from stretching out, they are provided with good additional lighting and a certain temperature regime (the room should be quite cool).

Lamp DHAZ/Reflux 70

Power, W: 70

Lamp luminous flux (Lm) : 5600

Requires 3 lamps.

DNA3/Reflux lamps however, their high cost must be taken into account, for example, a ready-made lamp for seedlings 250 W with DNA3 and electronic ballasts costs about 4600-5000 rubles.

Many fluorescent lamp manufacturers offer lamps with a spectrum optimized for plants. It makes sense to purchase such a lamp if you need to replace an old lamp: with the same power, a special lamp provides more “useful” light for plants. But if you're installing a new plant lighting system, don't bother with these specialized lamps, which are much more expensive than regular ones. Install a more powerful lamp with a high color rendering index (lamp marking - /9...). Its spectrum will contain all the necessary components, and it will provide much more light than a special lamp.

Common mistakes gardeners make

Most often, when additional illumination of tomato seedlings, gardeners make the following mistakes:

If burns form on the foliage of seedlings, this means that the lighting fixtures are located too close to the seedlings.
The foliage becomes faded and the shoots become elongated if the lamp is installed much higher than necessary or it has insufficient power.
If the lighting fixtures are installed on the side, the shoots of the plants may bend towards the lamps. In this case, they must be moved upstairs.
Using simple incandescent lamps for additional lighting does not give the desired effect, because their light is completely useless for plants.

Quantity is not just about hours. About watts, lux, kelvins and PAR

How much light do tomato seedlings need?

The required amount of light for tomato seedlings is from 8,000 lux to 20,000 lux.

For comparison: in the south in mid-March, early April - about 6000 lux, behind the window frame - 50-60% less. In addition, glass does not transmit the blue spectrum of radiation, which is important.

About the temperature of light

When choosing a lamp, focus on its color temperature. It is measured in kelvins (K). The lower the temperature, the color is “warmer”. So, 2700-3000 K is yellow, blue is 5000-6000 K.

Which lamps are better? In the range of 4000-4500 K, daytime range.

About power and light hours

The power of all lamps is different. Based on the backlight standard, the power density for metal halide lamps is about 80 W/m2, for mercury lamps (not recommended for use) up to 160-200 W/m2.

So, let’s calculate how many lamps we need.

The minimum lighting level for tomato is from 40 W/m2 (with a photoperiod of 16 hours - 0.64 kW × h/m2 per day, with 20 hours - 0.8 kW × h/m2 per day).

If the area of the nursery is 1 m2, and there are 100 W lamps, then 2 lamps are needed for optimal illumination of the tomatoes.

The minimum lighting for a tomato is from 2000-3000 lux.
For the formation of flowers - from 4-5 thousand lux.
The optimal value for the growing season is 20 lux. and higher, up to 35 thousand lux.

About the spectrum: color is different

About the spectrum of a lamp for seedlings: which one is needed, what it affects and how, the amount and spectrum of illumination.
To illuminate tomatoes and more, you need lamps with a full spectrum of radiation.

Red color is needed during germination and in the looping phase - it promotes the production of chlorophyll, the synthesis of which is not affected by other colors of the spectrum, during filling.
Blue stimulates cell growth, incl. in cross section: if it is absent, the stems are elongated; if present, the seedlings are strong and stocky.

For maximum photosynthesis, the red-orange zone of the spectrum (600-700 nm) is needed with a maximum red value of 675 nm. The blue-blue zone of the spectrum (blue) is also important - 400-510 nm.

In total, the correct lamp should emit about 670 nm of the red spectrum, blue spectrum - 440 nm.

The maximum level of photosynthesis is achieved when exposed to red and orange light (610-670 nm). The blue spectrum (blue-blue zone) is also required - 400-510 nm. Correctly selected lamps should emit about 440 nm of the blue spectrum and 660 nm of the red spectrum.

Backlight quality control

No matter how the illumination is carried out, with industrial lamps, or with a DIY LED lamp for tomato seedlings, and at your own discretion, in any case, the light should be distributed evenly throughout the plant cells.

If any area is not illuminated enough, this will be noticeable after a while, as the seedlings will stretch out or have a pale green color. In this case, you need to adjust both the angle of illumination and the distance.

An indicator of insufficient illumination is the “pulling” of sprouts towards the window; normally, seedlings should grow strictly vertically.

Phytolamps

These are specially made devices for supplementary illumination of seedlings. These lamps are similar in appearance to LED lamps. The glow spectrum of phytolamps is pink-violet. They also emit some ultraviolet and infrared light. The first is necessary to increase the frost resistance of plants, and the second is to stimulate metabolic processes.

A phytolamp is an ideal lamp for growing seedlings. Thanks to special clamps, it can be mounted on the ceiling. In addition, the phytolamp is equipped with a dimmer.

Soil temperature

Tomato seedlings must be planted only in well-warmed soil. There is no clear answer to the optimal soil temperature, since the sprout is affected not only by the temperature regime of the roots, but also by the moisture contained in the soil. The optimal temperature is considered to be 20-22 degrees. In this temperature regime, tomato seedlings feel great and can produce maximum yield. For seedlings of tall varieties for greenhouses, temperatures below 12 degrees will be dangerous. At this temperature, growth will stop and the pollen will become sterile. Also dangerous is a regime where the temperature reaches over 30 degrees.

At what temperature do they germinate?

Seed pipping occurs at room temperature. If, after pipping, the seeds are placed in unheated soil, the seedlings may not sprout at all. The optimal temperature for seedlings is 24-26 degrees. It is also important to note that the soil must be well moistened. The best conditions are to cover the container with soil with film or other plastic products. To achieve maximum results, you can place a sheet of foam plastic under the container with soil, which will ensure that the required temperature is maintained.

When to turn on the lights above the pepper

The switching time depends on the age of the plantings.

When the cotyledon leaves appear, the lamps can burn for three days without interruption. Having such light support, the seedlings will begin to grow quickly and develop well.
When the first true leaves appear, the daylight hours should last 14-16 hours.

At what time of day should you turn on the lights for the peppers?

In February and early March, turn on in the morning and leave until 20-00 hours. By the inclination of the peppers towards the window, you can judge the lack or sufficient light on the windowsill.
In April, the lights can only be turned on in the morning and evenings in this mode: from 6-00 in the morning until lunch, then from 16-19-00. It is advisable to have a timer, since it is impossible to light the seedlings around the clock.

Make your pick on time

If you grow tomato seedlings not in individual cups, but in a common container, they will need to be picked. This is necessary so that the plants develop normally as they grow and do not lack light, moisture and nutrients. In cramped conditions, plants will not be able to form a powerful root system, which will subsequently affect the development of plants, and, consequently, the harvest.

Gardening books usually recommend that you start picking when the plants have two true leaves. Some experienced gardeners advise starting picking when four true leaves appear. At this time, the plants are already quite strong and will better tolerate the transplantation procedure.

Another tip from experienced summer residents is to place 2-3 granules of superphosphate at the bottom of the glass when picking. Tomatoes are very sensitive to this nutrient. As the seedlings grow, the superphosphate granules will gradually dissolve and be used by the plants.

When picking, the plants are carefully placed one by one in cups and sprinkled with a layer of soil to the level of the seven-lobed (first) leaves.

Opinions are divided regarding pinching 1/3 of the root. Some gardeners advise not to injure the root system, while others believe that pinching is necessary for the formation of a branched root system.

After the picking procedure, plants are never immediately exposed to the window. The root system must be given the opportunity to take root. To do this, the plants need to be left in a cool place for a couple of days. They can be covered with a piece of plastic film, covering material, and sprayed with water from a spray bottle under the cover. In such conditions, it will be easier for the seedlings to endure the transplantation process.

While the plants are taking root, it is not recommended to feed them with fertilizers, otherwise burns to the root system may occur. Typically, fertilizing begins 10-14 days after picking.

Read more about picking tomatoes in the article Picking seedlings: nuances, tips, features of the process.

Why highlight seedlings?

Most tomato varieties have a fairly long growing season. That is why they are planted in the middle of winter, when the duration of daylight hours is still too short. In order for such plants to fully develop, special lighting is provided for the seedlings. With its help you can maintain optimal light conditions in winter.

If you refuse additional illumination of seedlings, certain problems may arise during cultivation. Due to insufficient light, tomato seedlings begin to stretch out their stems. Over time, elongated internodes appear on them.

This is due to the fact that in low light the process of photosynthesis begins to slow down in the bushes. If you don’t start lighting the seedlings in a timely manner, they will start to get sick.