Park's Original Bio Dome Seed-Starting System

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Grow bigger and better-rooted seedlings faster

A Park Seed Exclusive, the Bio Dome is crafted for optimal seed growth with vents to promote essential air flow, a floating planter to wick moisture to seeds from the bottom, and nutrient rich planter plugs to grow bigger, better seedlings. Seeds sold sep

If you're new to using the Bio Dome, let us sing the praises of this, our most POPULAR PRODUCT OF ALL TIME. Customers love it, and even experienced seed starters like us, who have been dropping marigold seeds into the soil since pre-school, have come to make the Bio Dome the ONLY SEED STARTING SYSTEM WE NEED. Here's why:

Climate Control: you can remove the clear vent as the plants grow, but at first, especially if you're starting seeds in late winter, it's a real boost of warmth and humidity. And the two adjustable vents at the top make sure that your plants get good air circulation at all times.

Incredible Rooting Medium: in each hole of the polystyrene planting tray is what we call a "bio sponge," a pre-formed plug of sterile medium with a hole already drilled in the top. The bio sponge is simply the best way we've ever found to reliably germinate and grow on seeds. We plant 1—ONLY ONE—seed in each bio sponge, even for difficult-to-germ varieties, and they nearly always sprout. (The only seeds you don't want to grow in the Bio Dome are those of root vegetables like carrots, beets, and radishes—they need more space to grow their tuber than the bio sponge allows.) In all our years, we've just never had results like this from any other seed-starting medium, and we've tried them all twice. The bio sponge offers the perfect blend of aeration and moisture to help seeds of all kinds grow and cuttings to root.

Bottom Watering: you water the base of this tray, NOT the bio sponges themselves. Put enough lukewarm water into the base so that the polystyrene tray floats. The bio sponges will wick up just the water they need. And as your plants grow, their roots will go down and out, instead of spiraling or fanning out near the surface as you often see with top-watered seedlings. It's impossible to over-water the Bio Dome.

Root Strength: this goes along with #3—these seedlings form LOTS of roots and grow them straight down and out, so that when it comes time to transplant the seedling, you can see roots sticking out all over the sides and bottom of the bio sponge.

Ease of Transplant: none of this business of transplanting the plug into a pot and then transplanting the plant out of the pot and into the soil. When you start your seeds in the Bio Dome, they can be transplanted straight into their final home. The bio sponge holds together, but the roots fan out easily beyond the sponge and into the garden or container soil.

Refills of the bio sponges and the polystyrene block are available so you can use your Bio Dome for years to come. Starting the Bio Dome is mess-free, easy, and so economical. Whether you want to start your entire garden indoors at winter's end or you just have to root your favorite geranium at season's end, rely on the Bio Dome. You'll be glad you did—we stake our good name on it.

Green base measures: 14 7/8'' long x 9 1/2'' wide x 2 1/4'' high
Clear top measures: 14 7/8'' long x 9 1/2'' wide x 4 1/2'' high


Skip Product Specs
Additional Characteristics Container, Easy Assembly, Indoor Growing, Seed Starting, Seedling Protection
Restrictions *Due to state restrictions we cannot ship to the following:
Canada, Guam, Puerto Rico, Virgin Islands

Product Review Summary

Based on 19 reviews
The average rating for this product is 4.5 out of 5 stars
Overall Rating: 4.0/5.0

Customer Reviews

March 30, 2022

Bio-dome 40

This shopper rated the product 5 out of 5 stars

Just day 5 after I started 15 pepper plants and 10 have germinated. Also planted 10 Lemon cucumbers, they've all germinated well. Planted another 10 Jalapeno and 10 Sweet Peppers two days ago, this my first bio-dome system works very well. It's on my workbench in shop under 4' LED, on a 12 hour timer. I put a 14" x 18" Pet Warmer pad underneath, which I believe is helping. I highly recommend these bio-dome systems to anyone looking to start there seeds early.

Ron from CO
March 26, 2022

Plants in Stasis

This shopper rated the product 1 out of 5 stars

I've used the Bio Dome system for 3 years, and up until this year I'd have recommended it to anyone. This year, I can't recommend it. I grow tomatoes for a nonprofit organization's plant sale, which is their major fund-raiser, so it's important that the plants look really good by the time of the sale. In 2020 and 2021, the tomatoes looked great right from the start. This year, the tomatoes germinated beautifully, then went into stasis, not even developing true leaf primordia for nearly 3 weeks. Once they started growing, they did fine, but losing those 3 weeks means they won't reach the size they should by the sale. This happened with 2 varieties of tomatoes (which I'd previously successfully grown in Bio Domes) and 2 sowing dates, so it was repeated. I also started both varieties both times in peat pellets -- plus an additional time to make up for the "hibernating" plants -- and they developed completely normally, so there was nothing wrong with the seed or my growing conditions. All seeds were grown under controlled conditions of light and temperature. There's something in the sponges this year that causes the seedlings to stall out. While this might not be a problem for someone growing plants for themselves, it's definitely something I can't risk in the future. This year's sponges also were not of the quality of past years. They were flimsy, squashed so the holes weren't obvious -- and soaking didn't help that -- tore easily, and some were in pieces in the package. I loved the system before -- I definitely don't love it now.

Nika van Tilburg from OR
March 24, 2022

Two Weeks In

This shopper rated the product 5 out of 5 stars

This is perfect for people just starting out working from seeds, or people who want to cut out some of the work. I spent maybe an hour soaking the plugs and dropping the seeds into the holes. In just days I got my first sprouts and so far, they all look happy. I don't mind having to transfer them into a bigger cups to later sow into the ground. I use a grow light with 5:1 red and blue light. Soon I'll be able to put them into direct sunlight!

DarofAvon from CO
March 11, 2022

Not a magic bullet

This shopper rated the product 3 out of 5 stars

Easy to plant and grow seedlings, however, the plugs themselves never break down. In addition, my plastic dome chipped when I set it down on my deck. I found that to be disappointing.

Angela from IL
March 03, 2022


This shopper rated the product 5 out of 5 stars

I am very pleased with the price, ease of use, and how it is working so far. My seedlings are working almost 100% compared to last year this is a much better return on my investment. Seeds are expensive but this system has so far worked great. Very happy with the results.

Michael Bielas from AZ

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