Your first month of hydroponics
You don't need a greenhouse or an agriculture degree to grow food hydroponically. You need the right system, a basic grip on pH, and the patience to not over-tinker for the first few weeks. Everything else you'll figure out as you go.
By The JustBeginning Editors · Published May 23, 2026
Hydroponics has a reputation for being technical and demanding. It isn’t — not for the first grow, and not if you pick the right system. The first month is almost entirely about learning to read your nutrient solution: what the numbers mean, when to top off, when to change it out completely. The plants do the rest.
Here’s what that month actually looks like, week by week.
Week 1: Setup and germination
The biggest decision you’ve already made: which system you’re running. If you chose Kratky (the passive, no-pump method), your setup is a jar, some net cups, clay pebbles, and nutrient solution. If you chose DWC, add an air pump and airline. Either way, week one is mostly germination — getting seeds started before the main system matters at all.
Germinate in rockwool. Soak a rockwool starter cube in pH 5.5 water for 30 minutes. Place one seed per cube, about half a centimeter deep. Put the cubes in a humidity dome or cover with plastic wrap, and set them somewhere warm (70–78°F is ideal). Most lettuce and herb seeds sprout in 3–5 days. Tomatoes and peppers take 7–10.
Mix your first nutrient solution. While seeds are germinating, mix your reservoir. Follow the nutrient manufacturer’s chart for vegetative growth at half-strength. Then measure pH and adjust to 5.8–6.2. Write down what pH you started at, how much up/down solution you added, and the final reading. This log becomes useful fast.
Check EC. Electrical conductivity tells you how concentrated your solution is. For seedlings going into their first reservoir, 0.8–1.2 EC is a safe starting range. Higher is fine for established plants; lower is safer while roots are new.
Week 2: Transplant and first roots
Once your seedling has its first true leaves (the pair after the seed leaves), it’s ready to move into the main system. Place the rockwool cube into the net cup and fill around it with rinsed clay pebbles. The cube should sit about halfway submerged in the nutrient solution — roots need to reach the solution, but the crown of the plant needs air.
Check pH every day this week. pH drifts — especially in a new reservoir where the plants haven’t yet established a stable uptake rhythm. 5.8–6.2 is your target. If it drifts toward 7.0, a few drops of pH Down brings it back. Keep your adjustments small: overshooting in the other direction is easy.
Don’t change the nutrient solution yet. New growers often dump and refill too early. The first week’s solution is fine as long as pH and EC are in range. Top off with plain pH-adjusted water as the level drops (the plant is drinking and evaporation is taking the rest).
Look at the roots. By day 5–7, you should see white root tips poking out of the net cup into the solution. Healthy hydroponic roots are white and fuzzy. Brown, slimy, or matted roots are a problem — usually caused by light leaking into the reservoir and growing algae. Wrap any clear containers in foil or opaque tape.
Week 3: Vegetative growth kicks in
This is when the plant starts noticeably changing day to day, and where most first-time growers get excited enough to start over-tinkering. Don’t change anything that’s working. If your pH is stable and the plant looks healthy, your job is to check and log, not to adjust.
What “healthy” looks like:
- Leaves are deep green (pale yellow means nitrogen deficiency; more likely it means pH is off)
- Leaves have no spots, curling, or crispy edges (those mean calcium or magnesium issues — check pH first before adding anything)
- The plant is visibly larger than it was two days ago
Your first full reservoir change. At day 14–21, dump the reservoir and mix fresh nutrient solution. This flushes any salt buildup and resets your ratios. The plant’s nutrient demands have grown since week one — mix your new batch at the full-strength recommendation on the label.
Week 4: Harvest or flowering
For lettuce and most herbs, week four is harvest week. Lettuce is ready when the outer leaves are the size you’d eat — you don’t have to pull the whole plant. Harvest outer leaves and let the center keep growing. A single lettuce plant can produce for 6–8 weeks this way.
For tomatoes and peppers, week four is when vegetative growth transitions toward flowering. You’ll see the first small flowers forming. This is when you switch your nutrient ratio toward the bloom/fruiting formula — more phosphorus, less nitrogen. The plant will tell you it’s ready: growth slows, flower sites appear, and the foliage looks slightly darker as the plant starts directing energy inward.
Take notes before starting a second grow. The most useful thing you can do at the end of month one is write down: what worked, what the most annoying part was, what you’d change about the system, and whether the crop matched your expectations. Your second grow will be dramatically smoother than the first, and it mostly comes from remembering what you actually did — not what you planned to do.
The most common first-grow kills
Almost every failed first hydroponic grow comes from one of four things:
pH out of range. The silent killer. Plants look fine for a few days while nutrients lock out, then start showing deficiency symptoms that look like totally different problems. If your plant looks sick, check pH before you do anything else.
Too much light too close. LEDs have come a long way, but “full power at 6 inches” will bleach and stress a seedling. Start with lights dimmed or raised high, then lower gradually as the plant hardens off.
Algae in the reservoir. Green water and slime on roots mean light is getting into your reservoir. Cover every light-transmitting surface. Algae competes for oxygen and nutrients, and the slime it creates coats roots enough to cause root rot.
Over-adjusting. Adding nutrients, pH up, pH down, and then more nutrients in the same day creates a chemical soup that’s impossible to diagnose. Make one change, wait 12 hours, check again. Patience is the skill hydroponics teaches.
What to grow on your second cycle
Once you’ve got one crop to harvest, the obvious next step is scaling slightly — either a second plant in the same system, or a second system alongside the first. The crops worth trying after lettuce:
- Basil and mint — fast, fragrant, cut-and-come-again for months
- Cherry tomatoes — more demanding than lettuce but extremely productive once going
- Spinach and kale — similar to lettuce, slightly more bitter, require a bit more light
- Cucumber — wants a DWC setup and a trellis, but yields are extraordinary
The technique stays the same. Only the nutrient ratios and light intensity shift.
Ready to buy your first system? Our hydroponics gear guide covers which system to start with, the nutrients worth buying, and the meters you genuinely can’t skip.