Many new growers are at first unaware of the need to separate plants during different stages of growth—I know I was. When I started growing indoors, I approached the process just like I approached outdoor gardening. I assumed annual plants would simply go through their life cycles if I gave them some soil, water and light.
Although this is true, I quickly discovered that the most successful indoor growers take full advantage of the heightened control they have over the growing environment to maintain a perpetual garden.
To put it a different way, many growers establish separate areas to meet the needs of their plants during the three major stages of plant growth for annuals: the seedling and cloning stage, the vegetative stage and the flowering stage.
By continually growing plants in each stage, a grower is constantly cycling seedlings or clones into the vegetative stage, moving vegetative plants into the flowering stage, and harvesting flowering plants once they mature.
Understanding the required areas and the timing for each stage are the two biggest things a grower needs to master in terms of maintaining a three-stage, perpetual indoor garden.
Seedlings and Clones
The seedling and clone cycle is the start of an annual plant’s journey. Although it requires the least amount of space, it is the hardest stage to master because the atmospheric conditions within this area must be controlled and kept consistent.
New growers should seriously consider some sort of environmental control for the seedling area. At this stage, most plants prefer warm temperatures (75-85°F) and high humidity (60-100%).
Seedling heat mats with thermostatic control, or temperature-controlled cloning machines, will help ensure these conditions are met. Light requirements for seedlings and clones can vary a little bit, but in most cases, a fluorescent T5 lighting fixture operating for 18-24 hours a day will suffice.
Clones taken from a mother plant take about two weeks to develop roots. Using this time frame, you can calculate when clones need to be taken so as not to interrupt the flow of the perpetual garden.
Many growers will take clones when it’s time to put other plants into the flowering room. And since most flowering plants take about eight weeks to mature, this will give the plants two weeks for root development, and six weeks for vegetative growth, before being cycled into the flowering room.
The vegetative cycle is the stage of growth when annual plants put on the majority of their green foliage. Annual plants in nature reproduce once a year and the vegetative stage is the stage that precedes the reproduction stage.
Essentially, the vegetative stage is the plant preparing itself structurally for reproduction. This stage of growth requires more space than the seedling or cloning stage, but not as much space as the flowering stage. A good rule of thumb is to plan on a vegetative area that is half the size of the flowering area.
Plants in the vegetative stage should be given at least 40 W of artificial light per square foot of garden space. Although some old-school growers still stand by HID lights for this stage, I recommend using T5 fluorescents for vegetative growth because they provide better light distribution.
When using an HID light for the vegetative stage, plants directly under the light will receive more light energy than those plants on the peripherals. To combat this, a grower has to either move the light or rotate their plants. With a T5 fluorescent fixture, the light is evenly dispersed due to the length of the bulbs. This means that, for the most part, plants can stay where they are without requiring rotation and man-handling.
Another advantage of T5 fluorescent lights is that they operate at a cooler temperature. Again, due to the length of the bulbs, the heat dissipates more evenly. There are some obvious advantages to a reduced heat load, including a reduction in operating costs.
However, the biggest advantage of the reduced heat load is the plants can be placed closer to the light source, without fear of them being burned or damaged. Plants closer to the light source will naturally create tighter node-spacing (space between branches).
This is especially advantageous when growing indoors because plants with more branches closer to the light source will have more flowers developing closer to the light source, equating to larger yields.
Other lighting technologies such as LEDs offer the same advantages as T5 fluorescents—think cooler operating temperatures and tighter node space development. Indoor gardening is all about maximizing light energy, and plants that go through the vegetative stage under T5 fluorescents or LEDs will naturally make more effective use of the light energy in the flowering stage.
The light cycle for the vegetative stage is usually 18-24 hours. I have always preferred an 18-hour light cycle, which gives my plants a little rest, but many successful growers swear by a 24-hour cycle.
One of the trickiest parts of managing a perpetual garden is knowing when to move clones or seedlings into the vegetative stage to allow them enough—but not too much—time in the vegetative stage.
The best way to gauge this is to document the growth of a plant until it reaches the height desired for the flowering stage. With this information, make a calculation using the total duration of the flowering stage to determine the best time to start vegetative plants.
For example, say you know your flower cycle takes eight weeks, and you have also determined that your vegetative plants reach the desired height in six weeks. To properly time your perpetual garden, you should start the vegetative growth stage two weeks after you begin each flowering cycle.
The flowering cycle is when all of the magic happens. Although it’s the final stage, the flowering area of an indoor garden should be the one designed first since its size must be determined by the maximum light energy you are able to provide. For most annual plants, calculate 40-60 W per square foot of garden space.
Once the size of the flowering stage has been determined, the sizes of the vegetative and seedling and cloning areas can also be determined. As mentioned earlier, since the plants in the vegetative stage will be about half the size of the mature plants in the flowering area, the vegetative area can be calculated as half of the area required for flowering. So if the flowering garden is 50 sq. ft., the vegetative space should be around 25 sq. ft.
One important consideration for the flowering area is light leaks. The photoperiod for the flowering room is 12 hours on and 12 hours off. Plants in the flowering stage must be kept completely dark during the lights-off period.
Most annual plant are photosensitive, which means their stage of growth is determined by the amount of light and dark they receive in a 24-hour period. A flowering plant that accidentally receives light during the lights-off period could revert back to vegetative growth and this could severely diminish yields.
There are a few different light technologies that can be used during the flowering stage. HIDs, especially HPS lighting systems, are still the most popular choice, but in recent years, growers have been converting their systems to LEDs, plasmas and fluorescents for their flowering rooms.
Growers who are able to juggle three growing areas at once end up with a more productive garden overall. When calculating the production of a garden, it is best to consider how many harvests will occur during a one-year period.
By keeping exclusive areas for the seedling or cloning stage and the vegetative stage, growers can continually move plants into their flowering room as they harvest. This perpetual style of growing is one of the biggest advantages of indoor gardening, as there is no down time.
The control over lighting and nutrients makes it easy for plants, regardless of which stage of growth they are in, to be grown in the same facility. All in all, designing growrooms with designated areas for the seedling, vegetative and flowering stages is the best way to make an indoor garden more productive and maximize your efforts.