Salad topper microgreens are the handful of tiny, bright greens you scatter over a salad, a bowl of noodles or a sandwich: a little radish heat, some broccoli crunch, a sweet pea shoot. Growing your own mix is easy in a shallow hydroponic tray. The one thing that decides whether it works is the mix itself, because every seed runs on its own clock, and a tray sown with the wrong partners gives you one crop ready and another still sprouting.
This guide is about getting the mix right. It covers which seeds finish together, why the best mix is often made after harvest rather than before sowing, how to lay out a tray for several kinds at once, and the numbers that keep every section healthy. If hydroponics is new to you, the apartment hydroponics beginner’s guide covers the basics first.
Salad Topper Microgreens at a Glance
Key takeaways
- Only mix seeds that finish within a day or two of each other. Radish is ready in 7 to 10 days and broccoli in 8 to 12, while pea shoots and sunflower take 10 to 14.
- The easiest mix is made after harvest: sow each kind in its own strip of the tray, cut each when it is ready, and toss them together.
- Keep micro herbs such as basil in their own tray, because they take 16 to 28 days.
- Feed lightly: plain water at first, EC 0.5 to 1.0 while pale, 0.8 to 1.2 once green, and never above 1.2.
- Give the tray 14 hours of light with the panel 10 to 12 inches above it, and keep humidity at 40 to 60 percent.
Harvest Windows for Common Topper Seeds
These are the harvest times from the crop table this site uses, counted from sowing. They decide which seeds can share a tray.
| Seed | Ready from sowing | Flavor on a salad |
|---|---|---|
| Radish | 7 to 10 days | Hot and peppery, so a little goes a long way |
| Broccoli | 8 to 12 days | Mild and fresh, which makes it a good base |
| Pea shoots | 10 to 14 days | Sweet and crunchy, like a fresh pea |
| Sunflower | 10 to 14 days | Nutty and substantial, although the hulls need picking off |
| Micro herbs, such as basil | 16 to 28 days | Intense herb flavor, but on a much slower clock |
Why Pre-Mixed Trays Often Disappoint
Seed companies sell salad and rainbow mixes, and they look like the obvious choice. The trouble is timing. Microgreens are cut once, all at the same moment, so a tray only works if everything in it is ready on the same day. When one seed is ready at 8 days and another at 14, you either cut the fast one past its best or cut the slow one before it has opened. A seed that sprouts fast also shades the one that sprouts slowly, so the late starter struggles from day one.
Seed size adds to it. Big seeds like pea and sunflower need soaking and grow tall and thick. Tiny seeds like broccoli sprout quickly on a damp mat. Scattered together, the big seeds sit on top of the small ones and the result is patchy. None of this means mixes cannot work. It means the mix has to be chosen, not grabbed off the shelf.
Choosing Seeds That Work Together
The rule is simple: sow together only what finishes together. Using the windows above:
- Radish and broccoli overlap well, since both are ready at roughly 8 to 10 days. That pairing gives heat plus a mild base, and it is the easiest true mix.
- Pea shoots and sunflower share a 10 to 14 day window and similar big seeds, so they can share a tray as well. Both need soaking before sowing, and the pea shoots guide covers the soak.
- Radish with pea or sunflower is a poor match, because the radish is past its best before the others are ready.
- Basil or other micro herbs should never go in with fast greens, because at 16 to 28 days they are still seedlings when the rest is done.
For any seed not listed here, check the days-to-harvest on the packet and only pair seeds within a day or two of each other. Buy seed sold for microgreens or sprouting, which is untreated and sold by weight. Garden packets can be coated with fungicide, which has no place on a crop you eat whole.
Watch Out for Gel-Forming Seeds
Some seeds form a sticky gel when wet. Basil and chia are the obvious ones. Scattered through a mix, they glue neighboring seeds together and hold moisture against them, which invites mold. Keep gel-forming seeds in their own tray or strip, sow them dry, and never soak them.
The Strip Method: Mix After You Cut
The most reliable salad topper mix is made in the bowl, not in the tray. Instead of blending seeds, sow each kind in its own strip across the tray, harvest each strip on its own day, and mix the cut greens together. If a whole tray is more than you need, a row of jars with one kind of seed in each works the same way on a smaller scale, and the guide to growing microgreens in jars shows the setup.
- Divide the tray into strips across its width, using a straight edge or a line drawn on the mat.
- Put the slowest crops at one end and the fastest at the other, so you can cut from one end without disturbing the rest.
- Sow slow seeds a few days before fast ones if you want them all ready at once, since pea and sunflower need a head start on radish.
- Cut each strip when it is ready, just above the mat, and keep it in a lined container in the fridge.
- Toss the strips together when you serve, in whatever proportion you like.
This gets around every timing problem, and it lets you change the recipe each time: more radish for heat, more pea for sweetness. It also keeps soaked big seeds and dry tiny seeds apart, so every strip gets sown the way its seed prefers.
Setting Up the Tray
Microgreens grow in two nested trays: one with holes holding a thin mat and the seed, sitting in one without holes that holds a shallow layer of solution. A standard 10×20 inch tray, about 1 to 1.5 inches deep, is the usual size, and the roots drink from below with no pump. The mat can be hemp or coco coir; it only anchors the seed and holds moisture.
- Wet the mat with plain water adjusted to pH 5.5 to 6.5, and tip off anything standing on top.
- Sow each strip evenly, with seeds close but not piled up. Where a packet gives a sowing rate for a 10×20 tray, scale it to the strip.
- Soak big seeds such as pea and sunflower first, and sow small and gel-forming seeds dry.
- Mist once, then cover the tray to keep it dark while the seeds sprout, which takes about 1 to 4 days depending on the seed.
- Uncover as soon as the seedlings lift the cover, and put the tray under light the same day.
Once the cover is off, pour solution into the bottom tray until it touches the underside of the top tray. The roots follow it down as they drink, and a layer of air opens up underneath. Check the level each evening, and if only the longest roots reach it, add a little more at the same strength, raising it by no more than about an inch. The seed starting kit roundup compares trays and domes, and the shopping list builder puts a setup together for you.
Light, Feeding and Humidity
All the fast topper greens share the same care, which is what makes the strip tray work.
- Light: 14 hours on and 10 off, with the panel 10 to 12 inches above the tray, at about 180 to 320 PPFD. A small LED bar covers a tray; the grow lights under $50 roundup compares them.
- Feed: plain water for the first days, EC 0.5 to 1.0 while the seedlings are pale, and 0.8 to 1.2 once they are green. Never go above 1.2, because a stronger mix burns the edges of a crop this young. An EC meter takes the guesswork out.
- pH: 5.5 to 6.5, checked with a pH meter. The pH and nutrient calculator works out small doses.
- Temperature: water and room at 65 to 75°F (18 to 24°C). Above 75°F, mold and damping-off become far more likely.
- Humidity: 40 to 60 percent, lower than most herbs like, with a small fan moving the air.
Treat the light height as a starting point for a typical home LED. When seedlings stretch and lean, lower the light an inch, and if the leaves look bleached, raise it. PPFD vs PAR vs lumens explains the numbers, and a plug-in timer from the compact timers roundup keeps the 14 hours honest. For mixing a weak feed accurately, see mixing two-part nutrients, and a clip-on fan keeps the air moving.
Harvesting and Mixing Your Toppers
Each strip is ready when its greens have opened their first leaves and stand about 1.5 to 3 inches tall, within the windows in the table above. Cut when the leaves are dry.
- Cut just above the mat with sharp scissors, a strip at a time.
- Swish the cut greens in cold water to float off seed hulls, especially sunflower.
- Dry them well, then store each kind in a container lined with a dry paper towel.
- Mix the kinds together when you serve, rather than storing them mixed.
Microgreens are cut once. Cut stems do not grow back, so the mat and roots go to the compost after the last strip, and the trays get washed with soapy water, rinsed, and wiped with diluted hydrogen peroxide before the next sowing. For a steady supply, start a new tray every week; succession planting covers the rhythm, and the seed to harvest calculator gives you dates.
Where these facts come from
🔗 Where these numbers come from
The harvest windows, pH, EC, light, temperature and humidity figures are the ones the crop table on this site uses for microgreens and micro herbs, and the crop sources page lists the research behind them. Virginia Cooperative Extension’s guide to microgreens indoors covers tray production and light, and Penn State Extension’s microgreens guide covers seed choice and harvest. Both the strip method and the light height in inches are this site’s own practice.
Troubleshooting a Mixed Tray
Mixed trays share the problems of any microgreen tray, plus a couple of their own.
| What you see | Most likely cause | What to do |
|---|---|---|
| One kind ready while another is still sprouting | Seeds with different harvest windows sown together | Pair seeds within a day or two, or switch to strips |
| Patchy growth with bare spots | Big and small seeds mixed, so the small ones were buried | Sow big and small seeds in separate strips |
| Mold around one patch | Gel-forming seeds holding water, especially in still air | Give gel seeds their own tray and add airflow |
| Tall, pale greens falling over | Too little light, or uncovered too late | Lower the light and uncover as soon as the seedlings lift the cover |
| Brown leaf edges | Feed stronger than 1.2 | Dilute with plain water until it reads 0.8 to 1.2 |
| Seedlings pinching at the base and collapsing | Damping-off, when the mat stays warm and wet | Compost the tray and clean everything before you sow again |
Mold or Root Hairs?
In the first days, fine white fuzz around the roots is usually root hairs, which vanish when you mist them. A gray web that spreads across several seedlings and smells musty is mold. Prevention is airflow, humidity at 40 to 60 percent, sensible sowing density, and no solution pooling on top of the mat. Tall, pale seedlings that barely grow are a different problem, covered in why seedlings stay small under grow lights. Damping-off, where seedlings pinch at the base and fall, cannot be rescued, so compost the tray, clean it well, and fix the conditions first. The guide to avoiding damping-off goes deeper, and cleaning a small system covers the clean-up.
Fungus Gnats
A damp mat attracts fungus gnats, whose larvae chew young roots. On a crop you eat raw within days, skip sprays. Yellow sticky traps catch the adults, and letting the top of the mat dry slightly between mistings breaks the cycle. Fungus gnats indoors has the full routine.
One Last Tip
Keep a sowing card for your favorite mix. Write down which seeds went in which strip, the day each was sown, and the day each strip was cut. After two or three trays you will know exactly how many days ahead to start the pea and sunflower so everything is ready on the same weekend. That little card turns a guessing game into a routine you can repeat every week without thinking about it.
Frequently Asked Questions
Which microgreens can be grown together in one tray?
Only seeds that finish within a day or two of each other. Radish at 7 to 10 days and broccoli at 8 to 12 pair well, and pea shoots and sunflower share a 10 to 14 day window. Keep micro herbs such as basil, at 16 to 28 days, in their own tray.
Are pre-mixed microgreen seed blends worth buying?
They can be, if the seeds in them finish together. Many blends mix fast and slow seeds, so one kind is past its best before another is ready, and big seeds bury small ones. Check the days to harvest of each seed in the blend, or sow each kind in its own strip and mix after cutting.
What is the strip method for mixed microgreens?
Sow each kind of seed in its own strip across the tray, slowest at one end and fastest at the other. Cut each strip when it is ready, store it separately, and toss the kinds together when you serve. It avoids every timing problem and lets you change the mix each time.
Do microgreens need nutrients?
Only a little. Use plain water for the first days, then EC 0.5 to 1.0 while the seedlings are pale and 0.8 to 1.2 once they are green. Never go above 1.2, because a strong feed burns the edges of such a young crop instead of growing bigger greens.
Can I add basil to a microgreen salad mix?
Yes, but grow it separately. Micro basil takes 16 to 28 days, far longer than radish or broccoli, and its seed forms a sticky gel that holds moisture against neighboring seeds. Grow it in its own tray and add the cut leaves to the mix at the end.
Which microgreen seeds should I soak first?
Big seeds such as pea and sunflower benefit from a soak before sowing, because they sprout faster and more evenly. Small seeds such as broccoli and radish can go on the damp mat dry. Never soak gel-forming seeds like basil or chia, since they clump into a jelly.
How much light do salad topper microgreens need?
Give the tray 14 hours on and 10 off, with the light 10 to 12 inches above it, at about 180 to 320 PPFD. A small LED bar covers a standard tray. Lower the light if the greens stretch and lean, and raise it if the leaves look bleached.
Do microgreens grow back after cutting?
No. Microgreens are cut once, and the stems do not regrow. Compost the mat and roots after the last strip, wash and disinfect the trays, and sow again. Starting a new tray every week keeps a steady supply of toppers coming.
How should I store cut microgreens?
Cut them when the leaves are dry, rinse off any hulls, dry them well, and store each kind in a container lined with a dry paper towel in the fridge. Mix the kinds when you serve rather than storing them mixed, because they keep for different lengths of time.
Why is there white fuzz on my microgreen tray?
Fine white hairs around the roots in the first days are root hairs and vanish when misted. A gray web spreading over several seedlings is mold, usually from damp, still air, dense sowing or gel-forming seeds. Add airflow, keep humidity at 40 to 60 percent and sow thinner next time.
