There are no significant savings when shopping for plants online compared to purchasing at a local nursery. You may think you are getting a deal but there will be a big discrepancy in sizes - you may be paying a lower price online but the plant will be tiny compared to what you can purchase in person. So it's a bit of an apples to oranges situation. And typically there will be shipping costs involved as well, boosting the overall cost.

Plant shopping online makes the most sense if you cannot locate the stock you want locally or want something rather rare that is not commonly found in most retail nurseries. Or if you want to start with very small specimens........as an example, it is easier to locate plugs of groundcovers or other plants you need in quantity by mail order. But plugs are miniscule examples of the plants - the starter forms of the same plants local retail nurseries sell in larger, more mature sizes.

If you can develop a relationship with a landscaper or someone else in the trade, you may be able to gain access to wholesale nurseries and the difference in retail versus wholesale pricing can be significant. Or barring that possibility, your local nursery may offer a discount based on volume purchasing. And then there are the end of season sales some nurseries offer as well as all the spring plant sales. Most folks find that purchasing plants over time for a renovated landscape makes the most economical sense. Focus on the biggest things first (specimen trees or privacy screening plants) and center your budget on those. Fill in with other smaller shrubs and perennials over time. Or replant the garden in sections, prioritizing what areas are the most important first, then phasing in the rest over time.

But don't think you are necessarily going to realize big savings by doing mail order. If you are buying plants of comparable size and maturity, purchasing locally in person is going to come out ahead.

If pricing is a priority wait for fall clearance sales and buy locally, so you can see the stock in person before purchasing. And not pay additional shipping charges, which can be considerable.

Fall is the best time to plant cold hardy plants anyway. The two main disadvantages to waiting until fall to buy from local garden centers are significantly reduced selection (in comparison to spring in particular) and in many instances significantly reduced quality, the plants having often been sitting around in retail sales yards for months - without having gotten the benefit of commercial grower fertilization and watering regimes. (Avoid material with poor foliage color - plants can look quite green and still be seriously nutrient deficient. If they are pale green or yellowish they are really bad off, may often fail to establish after placement in final planting sites - those instances where such material does green up and recover is not a universally guaranteed outcome by any means).