Essentially, growing indoor houseplants requires much the same pot, soil, and planting preparation that a pot plant grown outdoors does. There are differences, however, so I’ll list the basic requirements, even though they are similar to those for outdoor container plantings.

1. Use the Right Size Container!

Indoor plants do not need as big a pot as outdoor-grown plants, because they tend to grow much more slowly. You still, however, need a pot at lest twice the size of the root ball of your transplant, and if the plant is very immature, allow 4 to 6 times the size of the root ball. Of course, this does not apply to those plants that like to be pot bound in order to bloom – Amaryllis, Clivia, Orchids and Rex Begonias are examples of plants that won’t bloom or do well unless pot bound.

2. A Good Watering System

Bottom watering is generally best for pot plants, discouraging disease, and keeping the potting mix evenly moist. A self-watering pot with a water reservoir in the bottom works well, and, indeed, is the best way to grow African Violets, which don’t like to be handled or splashed. A saucer under your pot also works well for bottom watering, for you simply pour water into the saucer and let capillary action pull the water up into the pot through drainage holes. You can optimize bottom watering by placing a wick of felt or water-conducting cord in the bottom of your pot when planting, and letting the end extend down into the saucer to help move water up into the potting mix. If you water from overhead, a watering pot with a long, small spout is good for controlling where the water goes, and keeping it off the leaves of your plant. Another way to provide bottom water and also humidity is to select a metal tray (copper is pretty and will not rust), fill the bottom with a layer decorative pebbles and place your pot or pots on top of the pebbles. Fill the tray with water to the bottom of the pots. This will not only water your pots, but also provide evaporation to humidify the air around your plants.

3. Good Drainage

This is the other part of proper watering. Yes, a container can have too much water! There are probably more plants killed with over watering than from any other cause. A few plants (Juncus, some of the carnivorous plants,anything that likes boggy conditions) do like to have a little standing water at their roots, though most plants’ roots rot in such situations. Other plants like to be extremely dry and pot bound, such as Orchids and Clivia. For most plants, however, the ideal is an evenly moist, but well-drained soil! Evenly moist generally means that you water when the top inch of the medium is dry to the touch. If a plant likes to be dry between waterings, let almost the entire pot dry out before watering, though you should never let it go bone dry.

4. Humidity

Most plants like humidity between 30% to 50%. The watering system of pebbles in a tray filled with water (see 2 above) helps provide good humidity. You can also have a humidifier in the room with your pot plants, and if you place your plants in a group (but not touching), this will also help keep humidity up in their vicinity.

5. Good Air Circulation

Do not crowd your house plants close together, but leave a little space between them. They need plenty of gentle air circulation to lessen the chance of disease and to help them get plenty of carbon dioxide, which they need for photosynthesis. Be sure the air movement is gentle; a cold draft can stress your plants and cause them to lose leaves. Be careful of opening a window near your house plants in the cold of winter, and also of placing them in the direct line of air from your air conditioner in summer. A humidifier will also generate some air circulation, while providing moisture that house plants need.

6. Plenty of Nutrients

The plant has no means of getting nutrients except from the growing medium in its pot, so you will have to feed your indoor plants with plant food. As long as the plant is blooming or in active growth, you can feed once a month with full-strength fertilizer (carefully follow the label on whatever fertilizer you choose). However, you will have more even results if you feed every two weeks with a 1/2 strength solution, or every week with a 1/4 strength solution. Most fertilizers have salts, and if you see a whitish buildup on the rim of the pot or on top of the potting mix, you should flush the soil out with water for at least half an hour, or better, yet, discard the soil in the pot and start over. Of course, you can avoid this concern by using a natural plant food like Algoflash for Houseplants, which has a 100% natually occurring mineral base.

Some plants bloom best if somewhat starved for nutrients, and if given great growing conditions will produce lots of foliage, but not many flowers. Check the Encyclopedia section of this book to determine the specific recommendations for the plant you wish to grow.

7. Preparing Your Container

1. Choose a container with a drainage hole in the bottom, or a self-watering container, which will have the drainage hole(s) incorporated in the inner pot. You may want to line the bottom of the pot with irregularly shaped stones to further promote good drainage (though this should NOT be done with a self-watering container!). Be sure the drainage holes are not obstructed. You might have to check them periodically to be sure they are not blocked. If you use a decorative pot with no drainage holes, use it only as a cache-pot and place your plant, pot and all, into it (this is called double potting). Be sure to drain any excess water from the outside pot after watering, unless you are growing a bog-loving plant, such as Juncus, that loves to sit in an inch or so of water.
2. Use a soilless medium like Park’s Container Potting Mix, which will provide your plants the proper drainage and tilth. Mix timed-release fertilizer into the potting mix according to the instructions on the fertilizer container.
3. Place the potting mix in a plastic tub or bucket and slowly add water while gently mixing, until the growing mix is moist but not damp. Add the moistened mix to the container until it is 3/4 full. Remove the plants from their pots or communal tray (break up the sides of the root balls with your thumbs if they are pot-bound) and set the plants in the mix. Then add more potting mix until it is within 1 to 2 inches of the brim and tamp it down lightly. If the plants are small relative to the new container size, plant them at the same level that they were in their pot, so the top of the soil in their original pot is at the same level as the soil in the container.
4. Water thoroughly.

8. Provide Enough Light Plants use blue to violet light to produce foliage and regulate respiration, and orange and red light for growth, maturity and flowering. You can use fluorescent household cool white light (strong in blue and green) combined with household fluorescent warm white light (strong in red and orange) for plants with low to medium light requirements. If you need high intensity growing lights for plants that need a lot of light, there are a number of plant lights on the market that come close to providing the full spectrum normally provided by the sun, containing the correct amount of blue, red and far red for plant life. Some plants, like Clivia, do perfectly well in low light conditions. Others need plenty of light to perform well. Particularly in winter, if you have limited light or small windowsills, you should consider supplementing your natural light with growing lights if you want your indoor plants to look their best. A fluorescent light garden can be placed pretty much anywhere, since you don’t have to rely on natural light from a window. Under a shelf, on a bookcase, on a kitchen counter or on a table in your den or bedroom can all become a mini-garden in your house.Plants to grow in low or indirect light include Clivia, the Rex Begonias, African Violets, and Philodendrons. They will all tolerate fairly low or indirect lighting conditions, though they will perhaps be more full and robust with more intense light.

Plants requiring medium light conditions (that will grow and bloom under a Gro-Lux light) include Achimines, Abutilon, fibrous Begonias, Cyclamen, Episcia, Impatiens, Primrose, and Sinningia and Hypoestes. Pretty much all green foliage plants, like Asparagus Ferns, will grow under a combination of cool and warm white household fluorescent lights.

Plants that require high, intense light (they need wide-spectrum growing lights if you do not have a very well-lit place for them) include Cacti and other succulents like the Sempervivums, Calceolaria, Calla, Senecio, Fuchsia, Geranium, Kalanchoe, Lantana, Linaria, Nemesia, Orchids, Passiflora, Schizanthus, and Streptocarpus.

If the leaves turn downward or look sunburned, they are getting too much light, and the light needs to be raised or the plant needs to be moved farther away from the light. If the plants stretch upward and do not flower as they should, this is an indication that they need more light.

One final word about growing under lights concerns the length of time the lights should burn each day. An automatic timer is very helpful in providing the consistent lighting conditions the plants need to flourish. As in nature, different plants require different amounts of light. Following are some general guidelines:

1. Seed flats of annuals, vegetables, herbs and perennials can be lighted for 12 up to 24 hours a day until germination occurs, after which the light should be 12 to 14 hours a day.
2. Most house plants like 14 to 16 hours of light a day when flowering.
3. Foliage plants do well under 12 to 14 hours of light a day.
4. Some plants are affected by photoperiodism. This means they will bloom only when their requirements of darkness are met. Plants that like short nights (this means they get 14 to 18 hours of light a day), include tuberous Begonias and some annuals. Plants that like long nights (they need only 10 hours of light per day to flower) are much more numerous. Some of the long-night plants are: Cineraria, Leucanthemum (Chrysanthemum), Cyclamen, Kalanchoe and Gardenias.

So now I have imparted to you almost everything I and the people here at Park know about gardening successfully from seed! Chapter V lists the relevant plant families for the seed covered in this book. Chapter VI contains the botanical listing of several hundred genera and species of seed, along with pretty much all the information about growing each that we here at Park have gleaned in over 100 years of gardening. I hope you will find all you need to successfully grow your own seed!