There has been extensive research done through university horticultural programs and grower-shared experience to identify ideal PPM ranges that allow each plant to thrive. Below we have grouped plants that grow together in ideal common ranges. Note that some plants can tolerate lower or higher PPM ranges than otherwise noted, but you may see the affects of being outside of ideal ranges affect the growth and health of the plant and any output levels. Keep in mind that plants can grow up to 30% faster in hydroponic environments because they are getting ideal nutrients that help them thrive.

We recommend the following pH and PPM meters (we have used all of these before):
• pH Meter: https://amzn.to/2ZKymvP
• PPM/TDS Meter: https://amzn.to/2WbFqRp
• Combo 5-in-1 pH and PPM Meter (we currently use this one): https://amzn.to/3e9WwVL

COOL SEASON (SPRING | FALL)

COOL SEASON PLANTS THAT CAN GROW AT SIMILAR HYDROPONIC / AEROPONIC SYSTEM RANGES
IN THE 700-750 PPM / TDS RANGE:

PLACEMENT ON T.G.	PPM	PH	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Arugula | Roquette	560 – 840	6.0 – 7.0	45-60 days	Middle or Top
Artichoke	6.5 – 7.5	560-1260	2 years until ready	Bottom
Calendula	6.0	600-800	45-60 days	Bottom
Cilantro / Coriander	5.8 – 6.4	600-800	30 days/ 45 days	Bottom or Middle
Dandelion	6.4	600-800	9-15 days	Middle or Top
Fennel	6.4 – 6.8	700-980	80-115 days	Top
Lemon Balm	5.5 – 6.5	700-1120	70 days	Bottom or Middle
Lettuce & Romaine ◊	5.6 – 6.0	560-840	45-55 days/ 75-85 days	Middle or Top
Menarda (Bee Balm)	5.5 – 6.0	600-1200	110-120 days	Bottom or Middle
Mustard Greens	6.0-7.5	600-1000	30-40 days	Middle or Top
Nasturtiums	6.1–7.8	700-1000	35-52 days	Bottom or Middle
Oregano	6.0 – 7.5	750-1000	45 days	Top or Middle
Pansy	5.7 – 6.2	375-750	70-104 days	Top or Middle
Parsley ◊	5.5 – 6.0	560-1260	70-90 days	Middle or Top
Rosemary	5.5 – 6.0	700-1120	90-400 days	Middle
Sage	5.5 – 6.0	700-1120	75-80 days	Middle or Top
Thyme	5.5 – 7.0	560-1120	70 days	Middle or Top
Watercress	6.5 – 6.8	280-1260	55-70 days	Middle or Top

COOL SEASON PLANTS THAT CAN GROW AT SIMILAR HYDROPONIC / AEROPONIC SYSTEM RANGES
IN THE 900-1000 PPM / TDS RANGE:

PLANT NAME	PPM	PH	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN.
Artichoke	6.5 – 7.5	560-1260	2 years until ready	Bottom
Chives	6.1 – 6.8	900-1100	60 days	Middle or Top
Dill	5.5 – 6.0	800-1200	70-90 days	Bottom
Fennel	6.4 – 6.8	700-980	80-115 days	Top
Lemon Balm	5.5 – 6.5	700-1120	70 days	Bottom or Middle
Kale	6.0 – 7.5	900-1500	70-80 days	Bottom or Middle
Leek	6.5 – 7.0	980-1260	120 to 170 days
Menarda (Bee Balm)	5.5 – 6.0	600-1200	110-120 days	Bottom or Middle
Mustard Greens	6.0-7.5	600-1000	30-40 days	Middle or Top
Nasturtiums	6.1–7.8	700-1000	35-52 days	Bottom or Middle
Oregano	6.0 – 7.5	750-1000	45 days	Top or Middle
Parsley ◊	5.5 – 6.0	560-1260	70-90 days	Top or Middle
Peas	6.0 – 7.0	980-1260	70-100 days	Bottom or Middle
Rosemary	5.5 – 6.0	700-1120	90-400 days	Middle
Sage	5.5 – 6.0	700-1120	75-80 days	Middle or Top
Thyme	5.5 – 7.0	560-1120	70 days	Middle or Top
Watercress	6.5 – 6.8	280-1260	55-70 days	Middle or Top

COOL SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1200-1300 PPM RANGE:

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN.
Bok Choy	6.5 – 7.5	1120-1750	45-60 days	Middle or Top
Broad Bean (Fava Bean)	6.0 – 6.5	1260-1540	75-80 days	Spring Only
Cauliflower	6.0-7.0	1050-1400	55-100 days	Bottom or Middle
Celery	6.5	1260-1680	100-130 days from transplant	Top
Kale	6.0 – 7.5	900-1500	70-80 days	Bottom or Middle
Marjoram	6.0 – 8.0	1120-1400	60 days	Top or Middle
Parsley ◊	5.5 – 6.0	560-1260	70-90 days	Middle or Top
Purslane	5.5 – 7.0	1250-1500	60 days	Middle or Top
Spinach ◊	5.8 – 6.2	1260-1680	25 days	Middle or Top
Strawberries	6.5 – 6.8	1260-1580	Buy as starts	Middle or Top
Swiss Chard*	6.6 – 7.0	1260-1690	55-60 days	Middle or Top
Watercress	6.5 – 6.8	280-1260	66-70 days	Middle or Top

COOL SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1400-1575 PPM RANGE:

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDE.
Beet Root	6.0 – 6.5	1260-3500	45-65 days	—
Bok Choy	6.5 – 7.5	1120-1750	45-60 days	Middle or Top
Broad Bean (Fava Bean)	6.0 – 6.5	1260-1540	75-80 days	Spring Only
Cauliflower	6.0-7.0	1050-1400	55-100 days	Bottom or Middle
Celery	6.5	1260-1680	100-130 days from transplant	Top
Kale	6.0 – 7.5	900-1500	70-80 days	Bottom or Middle
Mint	5.5 – 6.0	1400-1680	60 days	Middle
Purslane	5.5 – 7.0	1250-1500	60 days	Middle or Top
Radicchio, Endive, Chicory	5.5 – 6.0	1400-1680	37-44 days	Middle or Top
Spinach ◊	5.8 – 6.2	1260-1680	25 days	Middle or Top
Strawberries	6.5 – 6.8	1260-1580	Purchase as 1 year old starts	Middle or Top
Swiss Chard	6.6 – 7.0	1260-1690	55-60 days	Middle or Top

COOL SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1950-1975 PPM RANGE:

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Beet Root	6.0 – 6.5	1260-3500	45-65 days	Top
Cabbage	6.2 – 6.6	1750-2100	80 to 180 days	Bottom

---

WARM SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 800-900 PPM RANGE:

PPM	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Basil	5.8 – 6.8	800-900	60-65 days	Middle or Top

WARM SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1260-1300 PPM RANGE.

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Cucumber	5.5 – 6.0	1190-1750	50-70 days	Bottom w/ support
Pumpkin	5.5 – 7.5	1260-1680	90-100 days	Bottom
Squash (Summer)	5.0 – 6.0	1260-1680	50-65 days	Bottom w/ support
Watermelon	5.8	1260-1680	65-90 days	Bottom
Zucchini	6.0	1260-1680	35-55 days	Bottom w/ support

WARM SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1400-1575 PPM RANGE:

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Beans (Common)	6.0 – 6.5	1400-2800	85-120 days	Bottom or Middle w/ support
Cucumber	5.5 – 6.0	1190-1750	50-70 days	Bottom w/ support
Melon	5.5 – 6.0	1400-1700	80-100 days	Bottom w/ support
Okra ◊	6.5	1400-1680	50-65 days	Bottom w/ support
Peppers (Sweet Bell)	6.0 – 6.5	1400-2000	60-90 days	Bottom or Middle w/ support
Pumpkin	5.5 – 7.5	1260-1680	90-100 days	Bottom
Squash (Summer)	5.0 – 6.0	1260-1680	50-65 days	Bottom w/ support
Tomatillo (Husk Tomato)	6.0 – 6.5	1400-3500	80 days	Bottom w/ support
Tomato	6.0 – 6.5	1400-3500	100 days	Bottom w/ support
Watermelon	5.8	1260-1680	65-90 days	Bottom
Zucchini	6.0	1260-1680	35-55 days	Bottom w/ support

WARM SEASON PLANTS TO GROW IN HYDROPONIC / AEROPONIC SYSTEM IN THE 1950-2000 PPM RANGE:

PLANT NAME	PH	PPM	DAYS TO MATURITY	PLACEMENT ON TOWERGARDEN
Beans (Common)	6.0 – 6.5	1400-2800	85-120 days	Bottom or Middle w/ support
Broccoli	6.0 – 6.8	1960-2450	100-150 days	Bottom or Middle
Brussels Sprouts	6.5 – 7.5	1750-2100	100-110 days	Bottom
Eggplant	5.5 – 6.5	1750-2450	100-150 days	Bottom or Middle w/ support
Peppers (Hot)	5.8 – 6.1	1750-2000	150 days	Bottom or Middle w/ support
Peppers (Sweet Bell)	6.0 – 6.5	1400-2000	60-90 days	Bottom or Middle w/ support
Tomatillo (Husk Tomato)	6.0 – 6.5	1400-3500	80 days	Bottom w/ support
Tomato	6.0 – 6.5	1400-3500	100 days	Bottom w/ support

Note:

When calculating PPM for growing plants, you will want to start out low and build up to the range as the plant matures. Here are some guidelines of how we would approach tomatoes for example:

• Seedlings: 100- 250

Seedlings do not require a whole lot of nutrients. DO pre-soak your rock wool with an enzyme soak that will set up beneficial bacteria in your system that will aid in fighting disease. We typically add a teaspoon of liquid kelp to our watering can and then water gently from the top. Don’t let your rock wool sit in water (drain off excess kelp water back into your container). At this stage, we never check PPM knowing it is low by intention.

• Vegging Cycle (First Half): 300—500

When your seedlings are about an inch or two tall (and roots begin to peek out the bottom of your rock wool cube, it’s time to move your seedling into your system and offer it some low, but balanced nutrients. We recommend using Tower Tonic Mineral Blend which is a balanced formula of N-K-P for hydroponics.

• Vegging Cycle (Second Half): 500—900

When your plants are about 3″-4″ tall, you want to feed them more to support their vegetative growth.

• Flowering (First Half): 900—1500

When they begin to flower, you want to bump them up again in PPM nutrient levels. This is also where you can add any bloom boost products that may encourage additional blooms, but remember more is not always better. There are other methods besides nutrients for increasing production. (Check out our article on using red mulch for example.)

• Flowering (Second Half): 1500—2200 (or higher up to 3000 if you want to push the plant a bit to see how it responds. Watch for tip burn in the leaves as your indicator that you’ve gone too far.)

You will notice that in tomatoes, eggplants, and cucumbers, that as they set fruit they will become VERY thirsty (this is why we call them heavy feeders). They are really going to slurp up the nutrients and water so be sure to watch your reservoir checking it several times a week during the hottest months. The fruit they are producing holds a lot of water content within it, so good clean water and nutrients are especially essential at this stage of the growth cycle.

• End of Flower (Harvest Starting Period): 

When you begin to harvest your fruit, it is a good idea to do a water change (we do a water change at least once a month in cooler season and once every two weeks during warm season). When you put in fresh water, allow the system to run a couple of hours on just water (no nutrients). This is what is called a “flush” or also known as leeching helps plants sort of reset if you will and they will flush out excess salts and resetting and re-invigorating the plant. Re-add your nutrients and continue to grow your plant until the next water change.