Indoor Gardening

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Bring the Garden Indoors

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You don't have to watch your favorite tender plants die as winter comes upon us! Many of our dear growing friends can be over-wintered indoors. You can also root cuttings and get a head start on next year's garden by starting seeds in early to late winter.

All that's required is a spot to hang florescent fixtures from and a place to sit the plants below them. You can use a whole room, or a corner or a spot under a table!

Basements are ideal because they tend to be cooler and moister. And, for those of you who are hard to Christmas-shop for, well the answers lie below!  Here's what you'll need.

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Indoor Gardening Needs

The Facts of Light

plants under grow lightsFour foot long double fluorescent fixtures are the best choice.  Suspend these from the wall, ceiling, or the underside of a shelf or table with metal or plastic chains so that you can raise and lower as the plants require.  You can use the "cool white" bulbs if you are growing only foliage plants. For plants that flower or fruit, use full-spectrum bulbs. 

You do NOT need to pay $20+ for the fancy schmancy "grow-light" bulbs.  Optimum distance from the top of the plant to the light source is 2 inches.  For taller plants, propping an old, large mirror or mirrored mylar behind them helps bounce the light back on the plants.  Over-wintered plants will need 12 hours of light, and up to 16 hours for flowering plants and seedlings.


timerA good quality timer is a must - one that has easily changed on-off settings.  If all your plants require the same amount of light, one is enough.  Plug everything into a power bar and plug the power bar into the timer.  If some require longer lighting, then you will need to group your plants and use separate timers.  Bright window sills are adequate for small plants like herbs if there is at least 2 hours of direct sun.  Don't forget to turn the plants a quarter turn daily so they don't "reach" for the sun and get misshapen.


water canGet the largest dripless watering can you can lift! Keep it filled with water and always ensure that the water has sat at room temperature for at least 12 hours before using on your plants.  A liquid fertilizer added to the water is handy and the neatest way to go.  An all-purpose 10-15-10 to 20-20-20 is a safe formulation.  Use at 1/2 strength every time you fill the watering can.  That means if it calls for 1 oz per gallon, use 1/2 oz.

Don't forget something to catch the water that seeps out when you properly water your plants.  You can use the large plastic flats (usually 12-16 inches wide by 24 inches long) for starting seeds to hold a collection of pots.  Two of these fit nicely side by side under the 24 inch fluorescents. For larger plants use individual saucers.

misterFind a good quality spray mister, one that holds at least a quart of water.  Indoor plants need regular misting because the humidity isn't high enough in most homes.  Again, let the water sit at room temperature for at least 12 hours before using on your plants.  The mister can also hold fungicide or insecticide mixtures if these problems afflict your plants.

Just a-lookin' for a home…

3 tiered light standTwo to four tiered metal plant stands are the best way to hold many plants in a small footprint area.  These can be purchased in the $100 dollar and up range, or you can build one. 

If building one from wood products, beware of spider mites.  Use only new wood.  Sealing the dry wood with 2-3 coats of the water-base varathanes is also a good idea.  Don't forget that a table top and the floor underneath is a very handy 2 tiered plant stand.

Do it in the Dirt

package of soilless mix"Soiless" mixes are the safest growing medium for indoor plants, as they will not have naturally occurring fungal spores, algae or insect larvae.  Remember, YOU must provide all the nutrients for plants growing indoors.   

Basic Soiless Mix
3 parts Canadian sphagnum peat
2 parts Vermiculite
1 part Perlite
2 TBS Ground eggshells

Ew, What's that Smell?
(how to sterilize soil)

You can also sterilize your own garden or other soils.  After seedlings get their first 2 pair of leaves in sterilized soil, they should be transplanted into individual pots in a soil-based mix.  Sterilizing soil for seed germination is required to prevent pest and fungus problems.

Oven method:  

Place a 4-inch layer of moist soil in a baking pan. Cover tightly with foil.  Insert a candy or meat thermometer in the soil through the foil.  Put in oven at lowest temperature setting until the thermometer reads 82-93 degrees.  Leave pan in oven for half an hour longer, then remove and allow to cool 24 hours before using.

Pressure cooker method:

pressure cookerFill a pressure cooker (canning type) with 2 cups of water. Place a rack inside the cooker and stack shallow pans of soil (3/4 inch deep, on the rack. Leave space for steam to circulate.  Apply heat until the cooker reaches 10 pounds, maintaining it there for 15 minutes before removing from the stove.  When cooled, remove the pans and wait 24 hours before using the soil.

Plants for Indoor Gardens


rosemaryMany of our favorites can be over-wintered in their own pots, including tender herbaceous ones like impatiens, geraniums (below left), parsely, basil, and other herbs; shrubby ones like azaleas, hibiscus, fuschias and rosemary (right), and even some vines like mandevilla and passionflower. 

In most cases, you must cut back the plants quite drastically (especially the vines and geraniums) to ensure that they will be full and bushy, and to minimize the shock of the climate change on the plant.  Keep pinching back new shoots to encourage bushiness throughout the winter on flowering plants, vines, fuschia and rosemary. 

Pinch back basil and other herbs to keep from getting leggy.  Dry the herb trimmings for later use if you have more than you need at one time.

geraniumWhen you bring in your plants for the winter, check to see if they are pot-bound and pot up in a one-size larger pot if they are.  You should do this in spring when you put them outside, rather than fall, but better late than never.  

If you are digging up plants from the garden, leave as much native soil on the roots as you can to cause the least disturbance, and pot up in appropriate sized pots, adding soil-less mixture as required to fill.  Water all your plants well then bring in and put under lights.

For more information, see Fall Cleanup - the section on bringing plants indoors.  

See Houseplant Helper and Plant Problems for more information and tips on indoor care.

Mist them well when they are in place.  Keep the room as cool as you can until they begin to acclimatize to the indoor environment.  Then gradually let the temperature rise if necessary.

Raising from seed or cuttings

Seeds:  Many of our favorite flowering plants and herbs must be started in January to March for summer bloom, for example, schizanthus and impatiens, and the purple basil below. Others can be started as late as one month before planting-out after last frost.  In all cases, use the plastic flats with the inserts to hold individual plants (usually 12" by 24"- bottom portion is shown in the top photo).  These come in kits with a clear plastic top that keeps humidity in and lets light through.  Read the planting instructions carefully, as some purple basilseed cannot be covered with soil (e.g. impatiens). See the Seed Starter list for starting different types of seeds.  Time the lights for 14-16 hours a day, and place 1 inch above the top of the plastic cover. 

Once the first pair of true leaves emerges, lift one end of the plastic cover up for a few days to gradually accustom the seedlings to the drier air before removing it.  Plants like tomatoes and peppers may get tall and leggy very quickly.  Simply repot, planting the seedling deeper in a slightly larger pot.  Tomatoes and peppers root from the stem, so progressively deeper plantings as they grow indoors helps them develop large, deep root systems to get a good foothold in the garden later.  If you find that they are growing far too quickly, cut back on the light to about 10-12 hours a day.  See Seedling Helper for more information.

Cuttings:  Tip cuttings from coleus at left, bottom of the stem to just below a leaf node and remove the bottom leaves.  Remove any flower buds and nip off the growing tip to just above a leaf node.

coleus from tip cuttings Place the cutting in moist growing medium, and cover with a transparent cover to keep moisture in.  Plastic placed over a wire "cage" made of bent coat-hanger wire works well.  Secure the plastic around the pot with an elastic band.  Place in bright location or under lights that are 4 inches above the cuttings, but NOT in direct sun until signs of new growth appear.  For more information on cuttings and propagating plants, see Plant Propagation.

Give Your Plant Place a Name!

Don't just call it the "plant room".  Give your indoor garden a proper name like The Enchanted Garden, or something.  Post the name on pretty sign to hang over your indoor garden area.  Year round, you can always answer "How does your garden grow"!

Green Achers garden sign

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