I have mostly used Rootmaker 60 cell trays in the past. I have some of their 18 block setups to try this year. They also make 32 cell trays.
What general size do you prefer? Not necessarily Rootmaker, but ~18, ~30, ~50/60
Do you prefer different sizes for different types of seeds?
For example, 60 cell seems small for things like watermelon and squash. The 18 seems big for basil. But that’s just me think out loud.
I don’t care about the cell count. I prefer the deeper trays. Managing water is harder with them but the deep cells work better for me. I can leave them in longer too. I don’t think it matters it’s what works for you.
I do tomatoes, peppers, and eggplant in 48 cell trays (1204) from Morton Products. I also start a lot of seed in 1801 uncut. Why uncut? Because they work better uncut when carrying direct to the garden for transplant. I have used 72 cell trays in the past and found them woefully inadequate for most seedlings. I use 1020NH trays because I’m skilled in maintaining water levels with them.
I use 12, 16, and 32 once cups and they work fine. Basil is in smaller cups with pepper in larger cup.
I’m not sure who makes them. We picked them up from an estate sale. They are thick styrofoam, deep celled and 140 count trays. We have 2 for seed starts. I like to put my rootstock squash one one side and whatever we are putting on them on the other side.
In theory I like ones deep enough to start trees in, but 90% of the time they stay stacked in the garage, so smaller is better.
For me, it really just depends on the growth pattern and tolerance for up-potting. For vegetables/fruit vegetables, I roughly follow sizes from JM Fortier’s The Market Gardener and for flowers I typically rely on Johnny’s grow guides (at least until I figure out what works best for me). I really try to avoid using indoor lights during spring on anything bigger than 36-cell inserts but it’s necessary in some cases.
Here are some examples:
Alpine strawberries: Tiny seeds, take a while to germinate and 4-6 weeks from sowing to outgrow 288-cell trays. I needed a lot for some ground cover and to share, so I started them in a 288-tray, up-potted to 72s after maybe 5 weeks, and then planted out a bit later. This also applies for a lot of slow-germinating flowers with small seeds (e.g. lisianthus).
Melons and squash: I get a head start on the season by starting these in 5.5 inch square pots (8 per 1020 tray). I normally don’t grow anything under lights in pots this large, but these only need a few weeks and by the point I’m starting these I don’t really need the lights for everything else as it’s either moved outside or planted.
Salad veg: Most of this stuff I start in 98s and plant out in about a month or so, mostly because germination is spottier in the field.
Sweetpeas: Big seeds, send down deep roots, don’t like being up-potted. So I start these in deep 50-cell trays.
Tomatoes: Like the sweetpeas, I start these in the deep 50s. They don’t mind being up-potted but they fill out the 50s in a reasonable amount of time after germinating.
